Air

Can Viruses Be Filtered By Air Purifiers?

Because viruses are to small, most air purifiers cannot capture them effectively, although most claim to in their promotional material. Air purification systems that have HEPA filters, ultraviolet lights and electrostatic filters achieve the best results since none alone can guarantee consistent removal and eradication of viruses from the air stream.

HEPA Filters

HEPA filters have been used in biomedical applications since the 1940s to prevent the spread of airborne bacteria and viral organisms. Specific requirements for different types of HEPA classifications range from cleanroom quality to true HEPA filters to HEPA-like filters. True HEPA filters are available for the residential market and they are regulated by the United States Department of Energy (DOE) to be 99.997% efficient, allowing no more than 3 particles in 10,000 to penetrate the filter. Even the best HEPA filter will not kill viruses, however, and can lose its effectiveness at trapping viruses as the particulate matter builds up and causes more resistance to the airflow.

Air purifier manufacturer IQ Air has claimed to develop a HyperHEPA (IQ Air’s trademarked name for this technology) filter capable of removing particles down to .003 microns in size with 99.5% efficiency.  This is 100 times more effective than sta  IQ Air backs up its claims by measuring each shipped air purifier with a laser particle counter.  Conceivably, these IQ Air models could be the most effective units on the market in filtering viruses. Even though these purifiers are used in some hospitals and clean rooms, according to the EPA there is no standardized test available to measure the effectiveness of virus filtration.

Ultraviolet Germicidal Irradiation (UVGI)

Health care professionals use ultraviolet lights to neutralize airborne microorganisms like germs, bacteria or viruses, although some mold and bacteria spores are resistant to UV radiation. For residential applications, however, the EPA warns that there is no standard to measure the effectiveness of UV cleaners and portable units and they probably have a limited effectiveness in combating viruses.

For UV lights to be most effective they need to be exposed to the air flow longer than most residential units allow. Therefore, the most effective air purifier designs direct the UV lamp onto the HEPA filter so the particles trapped by the filter are treated by the UV lamp for a sufficient period of time to destroy the viruses.

Electrostatic Precipitators

This method of air purification uses opposing charges to cause particulates to stick together and fall out of the air and land on a collection plate. Filters capture very fine particulates, including viruses, but it does not kill them. According to EPA studies, efficiency declines rapidly as the collection plates become covered with debris and must be changed often if they are the sole air purification method. When combined with a HEPA filter and UV lamps, however, electrostatic units maintain their effectiveness much longer.

Photocatalytic Oxidation (PCO)

PCO cleaners uses hydroxyl radicals to remove gaseous pollutants but does not remove particulates. The EPA cautions that PCO cleaners’ effectiveness in residential settings is limited, and testing has produced inconclusive evidence of their effectiveness against volatile organic compounds (VOC). In fact, some PCO devices were found to produce new indoor air pollutants while failing to destroy existing pollutants.

Ozone Generators

According to the EPA, ozone generators can be a threat to public health despite claims they neutralize odors and irritants in the air. Although studies have proven that ozone removes certain biological contaminants from the air, data suggest that the resulting concentration of ozone would exceed acceptable standards, up to 5 to 10 times higher than recommended. Air purifiers that emit small amounts of ozone — .01 to .02 or less — are safe and do assist in removing viruses from the air stream.

Conclusion

• The EPA’s August 2009 report on air cleaner effectiveness indicates that standards are needed to guide tests in determining the effectiveness of air purifiers on virus removal.  Currently, no standard exists.

• Bottom line – Inconclusive.  HEPA filters may be able to capture some viruses and prolonged ultraviolet light may be able to kill viruses but with the lack of testing standards, effectiveness is currently unable to be determined.

Source information:

• EPAL Air Cleaner Guide – http://www.epa.gov/iaq/pubs/airclean.html
• EPA: Residential Air – http://www.epa.gov/iaq/pubs/residair.html#Defining_Efficiency_and_Effectiveness
• EPA: Ozone Generators – http://www.epa.gov/iaq/pubs/ozonegen.html
• IQ Air: HealthProPlus – http://www.iqair.com/residential/roomairpurifiers/
• Wikipedia: HEPA Filters – http://en.wikipedia.org/wiki/HEPA

Special Report Contents

1. Understanding Consumer Reports Air Purifier Ratings
2. Complaints Against the CR Rating System
3. Consumer Reports’ Accomplishments
4. Summary and Conclusion
5. Most Recent Consumer Reports Air Purifier Ratings (Years 2010, 2007, 2005)

Introduction

Many people consider buying an air purifier with hopes it will provide some form of relief for asthma and allergy symptoms. Although there is no clear-cut medical proof that the use of an air purifier alone can relieve respiratory symptoms, some consumers believe they are still a worthwhile purchase.

Air purifiers are designed to filter the air inside a room by removing any dust, pet dander, mold, pollen or other harmful pollutants that can cause respiratory problems.  However, there are few scientific tests that objectively evaluate the effectiveness of air purifiers and the claims made in marketing such products.

Consumer Reports is one organization that has sought to objectively test the effectiveness of select air purifier models. However, some of their test procedures have come under fire from a few companies in the air purifier industry, an industry expert, and a subscriber who had poor results with CR recommended air purifiers. 

This Air Purifier Guide Special Report seeks to help you understand the pros and cons of Consumer Reports’ air purification rating system.

Understanding Consumer Reports’ Ratings

Consumer Reports is a well-known, non-profit organization that conducts product testing on a variety of items consumers use every day. By providing non-biased reviews, they hope to guide buyers to the best products available in the market.

How Consumer Reports tests its air purifiers

Air purifier tests done by Consumer Reports are conducted in a controlled environment. Inside this controlled environment, usually a room or chamber, a tester introduces different outside variables that will eventually interact with the selected air purifier. A special system is also installed inside this room that will inject dust into the air, as well as smoke produced by a cigarette. A measurement is taken by the tester of the concentration of dust and smoke that’s floating in the air.

Consumer Reports video on buying an air purifier and a few brief comments on testing.

The next step places the air purifier that’s being tested into the room with the contaminated air. The air purifier is turned on and the tester starts measuring how long it takes for that particular unit to remove the dust and smoke from the air. The same procedures are then used on all the other units selected for testing.

After all the selected purifiers were tested, Consumer Reports noted that the performances of the air purifiers varied considerably among the brands tested. They suggested that buyers should look for room air purifiers with timers that can be set to turn the unit on or off when no one is at home. In addition, a filter indicator light should be included so the buyer will know when to clean or change the filter. It was also suggested that air purifiers that use ozone generators should not be used since they release ozone back into the air which has been proven to irritate the lungs.

Consumer Reports also reported that the following features are not worth considering when buying an air purifier.

1. Air purifies which state they remove odors from the air “usually” do not work and if they do work, they take too long to do the job.
2. Air quality sensors are not worth their extra cost.
3. If a person doesn’t have asthma, allergies or any other respiratory problems, they may not even need to buy an air purifier at all.

How Consumer Reports picks models to test

Consumer Reports’ testing strategy involves choosing a range of products within a particular market. They look for products with advanced technology and new features that fall within varying price categories. The product’s market share is examined, along with advertising and promotional materials used by the particular product manufacturer. Consumer Reports uses managers from their technical and editorial divisions to review select products which their analysts will then use to create a list of models to be tested. They also choose products that are available from the manufacturer for at least three months after Consumer Reports publishes its ratings report. (Further Reading – CR’s explanation of how they pick models to test)

Consumer Reports then sends out staff employees to purchase the selected products either online or from retail establishments located throughout the Northeast. They will also use shoppers located across the country to buy any best-selling regional brands.

During this entire process, Consumer Reports never reveals to any retailer that the product being purchased will be used in their testing program. Every product they use in testing is purchased at a retail store and not received directly from a manufacturer.

Complaints Against CR Air Purifier Ratings

Not everyone believes Consumer Reports product rating tests are accurate. In fact, a few air purifier manufacturers feel Consumer Reports’ tests are flawed. The following are companies and individuals who do not agree with CR’s testing methodology.

Complaint #1 – IQAir

IQAir North America, Incorporated, is part of the Swiss based company, IQAir Group. This company is the only educational partner in the portable air purifier industry that works with the American Lung Association. They are manufacturers of several air quality products including portable air purifiers that are used throughout the world by hospitals and other similar environments.

In November 2007, IQAir North America issued a press release that introduced some critical argumentative-points about Consumer Reports testing process. IQAir stated that Consumer Reports admitted they rated a specific air purifier as #1 for 15 years even though it produced potential ozone hazards. According to IQAir North America, the continued lack of in-depth comparisons done by Consumer Reports is

“still causing them to recommend inferior and potentially unhealthy products while failing to acknowledge IQAir’s vastly superior HealthPro Plus room air purifier.”

The President of IQAir, Frank Hammes, added, that it could take Consumer Reports another 15 years before they realize their entire test rating process is flawed. His belief is that Consumer Reports’ testing process holds little substance and is causing them to give the wrong recommendations to buyers.

In January 2006, IQAir met with Consumer Reports to recommend a number of ways they could improve upon their testing processes. One of IQAir’s suggestions was to rate air purifiers based on whether or not they produced ozone. Hammes stated that Consumer Reports “should test air purifiers as medical devices – not toasters.” According to Mr. Hammes, Consumer Reports listened to his advice and made the suggested changes.

The new rating procedures used by Consumer Reports caused the original #1 rated air purifier to now be rated at #28. Frank Hammes then commented, “If they (Consumer Reports) would incorporate all of the necessary changes to their review process, you would see every one of their top recommended products drop down in rating….They need to recognize that air purifiers are primarily purchased by people with allergies, asthma, and other respiratory conditions.”

Since IQAir’s HealthPro Plus air purifiers received top reviews from reputable sources worldwide, and they are used in medical environments and hospital in over 100 countries, IQAir suggested several criteria that Consumer Reports should use in their air purifier tests, going forward. The following information represents IQAir’s statements from their November 2007 press release.

1. Permanent Particle Removal – Many top recommended air purifiers tested by Consumer Reports use ionization which adds an electrical charge to particles so they will adhere to surfaces. These ionized particles are emitted into the air and fall onto floors, furniture and other surfaces. Consumer Reports informs buyers that these particles get trapped inside the air purifier, which is not true. Medical professionals are concerned that these particles can end up inside a person’s lung tissue causing allergies. Every time the unit is turned on or off, these particles get re-dispersed into the air. IQAir’s HealthPro Plus does not use ionization but rather a mechanical filtration process that permanently traps these particles inside its included HyperHEPA filter. The particles are never re-released into the air.
2. Long-Term Efficiency – Since air purifiers are purchased by hospitals and medical facilities, they need to continue to work over longer periods of time. Consumer Reports only tests air purifiers for their first 30 minutes of use. If long term testing were done on these air cleaners, Consumer Reports would find the air purifier’s performances deteriorated rapidly. By rating these air cleaners based on their high initial air flow, without longer periods of test time, Consumer Reports is not realizing that the air cleaners ”can lose as much as 50% of their initial function in just a few weeks.” IQAirs HealthPro Plus uses a high-grade HEPA filtration system that will never lose its efficiency.
3. Ultra-fine Particle Filtration – Eighty percent of all airborne particles are smaller than 0.1 microns. Consumer Reports only tests air purifiers for their filtration of “particles down to 0.1 microns.” Scientific studies have shown that airborne particles that are ultra-fine in size are the most harmful to a person’s health. They can increase a person’s risk of having a heart attack or stroke. The HealtPro Plus has been “tested and certified to filter down to 0.003 microns with a guaranteed minimum efficiency of over 99.5%.”
4. Gas and Chemical Filtration – A majority of the air purifiers tested by Consumer Reports do not contain any effective gas or chemical filtration systems that would back up their claims of being able to remove household odors from the air. One of the top reasons consumers look to purchase an air purifier is to remove odors from the air. Consumer Reports does not rate air purifiers based on gas or chemical filtration because this type of technology lowers the purifier’s airflow. In fact, they downgrade the ratings on air purifiers that include effective gas or chemical filtration. IQAir claims their HealthPro Plus air purifier “contains the most effective gas and chemical filtration ever available in a residential air purifier.”

IQAir believes their testing criteria must be followed by Consumer Reports if they wish to provide an accurate buying guide for consumers to help them choose the best air purifiers.

Complaint #2 – Asthma Advocate Lisa Whiting

Another related complaint against Consumer Reports’ tests was made by asthma advocate, Lisa Whiting. She claimed Consumer Reports air purifier ratings was misinforming consumers and could lead to very dangerous health situations. According to Ms. Whiting, Consumer Reports’ recommendations endangered her son’s life. After an incident occurred where her son went into full respiratory arrest due to asthma problems, she purchased several air purifiers that were recommended by Consumer Reports. None of the products worked, so she did her own research and ended up purchasing IQAir’s HealthPro Plus air purifier. Switching to that air purifier changed her son’s life for the better. (Ms. Whiting’s statements can be read in the IQ Air Press Release)

Complaint #3 – Absolute Air Cleaners and Purifiers, Inc.

Barry Cohen is the owner and operator of Absolute Air Cleaners and Purifiers, Inc. His business has been in existence since 1989, and specializes in HEPA air purifiers. In response to questions he receives from many of his customers, Mr. Cohen created a report which explains why Consumer Reports only tests “lower quality, inexpensive HEPA air cleaners and air purifiers,” and not any “higher quality” ones. According to Mr. Cohen, Consumer Reports magazine uses air purifiers that are easy to find and that have a large share of sales in the market. The brands they choose are low quality brands that are inexpensive and are sold in discount chain stores like Wal-Mart, Sears and Home Depot.

Cohen believes consumers are educated and use the internet to do their own research into the best air purifier brands. They can discover that there are affordable, higher quality HEPA air cleaners and air purifiers available such as EZ Air, TRACS and Austin Air. These brands are not tested by Consumer Reports. In a letter addressed to Consumer Reports magazine, Barry Cohen requested that they do testing and ratings on higher quality HEPA air cleaners and air purifiers. 

Consumer Reports’ Response to Barry Cohen

Consumer Reports responded with their own letter addressed to Mr. Cohen. In the letter, Consumer Reports’ Customer Relations Representative Paul Hanney stated the following:

1. Marketing analysts do research on each brand-name air purifier and select the ones that have the highest market share at that time the testing will begin. Secret shoppers also go out to purchase the selected models they have chosen to be tested. Sometimes, certain models may be excluded in the testing process if the shopping team cannot purchase those models due to unavailability.
2. Strict testing deadlines may also hinder the selection of specific models that are not readily available for purchase. A notation was made that any omitted models does not mean Consumer Reports believes they are poor performers.
3. Paul Hanney informed Barry Cohen that his letter would be forwarded to the appropriate technicians and editors for further review and consideration. Also, Consumer Reports would like to know what particular products consumers are interested in purchasing.

(For more information, read the full text of Cohen’s complaints and CR’s response)

Complaint #4 – Air Purifier Power

Ed Sherbenou is the creator of Air Purifier Power, a site dedicated to answering emails he receives from readers looking for information on air purifiers. He publishes the emails he receives and responses to them on his website so all readers can benefit from the information.

One area Mr. Sherbenou touched was the issue with Consumer Reports’ low ranking of well-respected air purifier brands. Consumer Reports rightly exposed some questionable practices from two allergy foundations that granted approval of Oreck and Sharper Image air purifiers which emitted ozone into the air.  However, when Consumer Reports gave the respect IQAir and Austin Air purifier units a poor rating in their 2005 issue, trust in Consumer Reports rating process became stained within the air purifier industry. The result was a higher market share, ozone-emitting air purifier receiving a higher rating versus the IQAir and Austin Air models which emit no ozone and have been shown in other tests to perform quite well.

Sherbenou suggests that Consumer Reports makes the following changes to make their tests more helpful:

1. Changing testing procedures to not be similar to the potentially flawed Clean Air Delivery Rate specs put forth by the pro-appliance manufacturer group AHAM
2. Testing for volatile organic compound, gas, and odor removal
3. Adding some type of sound-level-to-air-delivery-rate calculations in its reports to show measurements of the noise levels emitted from air purifiers. (He made a note of two air cleaners that have noise levels at different spectrums that are being rated as the same for sound levels in their report).
4. Including an “air delivery performance-to-sound ratio” should be used rather than rating air purifiers based solely on which fan is the loudest on high.

Consumer Reports’ Accomplishments

Despite the complaints against Consumer Reports’ ratings and test procedures, it is important to recognize the meaningful accomplishments they have made toward improving air purifier education and protecting the public from misleading claims.

Accomplishment #1 – Upholding Its Negative Reviews of the Sharper Image/Ionic Breeze Brand

In 2002, Consumers Reports’ tests showed the Ionic Breeze air purifier had

“almost no measurable reduction in airborne particles”

ysing CADR measuements. Sharper Image disagreed and believed their air purifier would perform better in longer running tests. Consumer Reports decided to run futher tests to see if the Ionic Breeze Quadra would improve performance. It was tested against the similar quality Honeywell Environizer and two higher scoring air cleaners. These were firstly the Friedrich Electrostatic Precipitator and secondly the Whirlpool HEPA Filter. Sharper Image’s Ionic Breeze Quadra did not perform well in these longer tests. Along with the Honeywell Environizer, the Ionic Breeze Quadra barely cleaned the air when compared to the other two higher scoring brands.

In 2003, Consumer Reports won a lawsuit filed against them by the Sharper Image Corporation who claimed Consumer Reports’ tests concluded that the Ionic Breeze Quadra air purifier was “ineffective” in removing any measurable airborne particles from the air. The U.S. District Court for the Northern District of California dismissed the suit claiming Sharper Image Corp. had not shown that Consumers Reports’ test protocols were scientifically invalid. Sharper Image also had not

“demonstrated a reasonable probability that any of the challenged statements were false.”

Accomplishment #2 – Exposing Health Risks From Ozone-Producing Air Purifiers

In 2005, Consumer Reports found that the Ionic Breeze Quadra S1737 SNX and four other competing brands did not clean the air and ultimately emitted “excessive amounts of ozone” into the air that could cause respiratory problems to anyone close to the units. The negative publicity surrounding Sharper Images Ionic Breeze Quadra air purifier eventually caused the company to file Chapter 11 bankruptcy on February 19, 2008.

Accomplishment #3 – Offering Tips For Improving Indoor Air Quality Without Buying An Air Purifier

Consumer Reports, along with the U.S. Environmental Protection Agency and the American Lung Association, advises consumers to try a few “common sense steps” before purchasing an air purifier. By following these tips, consumer may discover that they may not need to purchase an air purifier after all.

1. Vacuum your home often.
2. Do not smoke inside your home.
3. Keep pets out of bedrooms.
4. Remove carpeting and any other furnishing which can trap dust mites in its fibers.
5. Use mite proof pillow covers and mattress covers
6. Wash laundry in the hottest water possible
7. Open windows in your home whenever it’s possible.
8. Minimize your use of candles, air fresheners and wood burning fires.
9. If you need to use an exhaust fan in the kitchen, bathroom or laundry room, make sure they are outdoor venting fans, which can blow the air inside your home, out. This step can help expel excessive moisture, odors, and combustible gases from your home, thereby preventing mold and other allergen build-ups.
10. Do not store pesticides, chemicals, solvents, or glue inside your home.
11. Test your home for radon gas. This gas can cause lung cancer.
12. Properly maintain all heating equipment, fireplaces, chimneys, wood stoves and vents by installing carbon monoxide detectors inside your home. This will help avoid the risk of deadly carbon monoxide gas poisoning.
13. Lastly, do not run fuel-burning power equipment or idle your vehicle near your home. Avoid lighting a barbecue grill inside your garage, basement or in any other confined space that’s near your home.

By offering these tips, Consumer Reports has accurately educated its readership and possibly helped many avoid making an expensive air purifier purchase they didn’t really need.

Summary and Conclusion

Over the years, Consumer Reports has fielded complaints regarding their testing methodology for room air purifiers. A few companies in the air purification industry expressed their opinions publicly about what they claimed were unacceptable testing procedures used by Consumer Reports. Despite those claims, consumers still look to Consumer Reports as a source of objective air purifier testing.

The following are some of the reasons why Consumer Reports has maintained its standing as a reliable source of information that consumers can depend on to help them choose the best room air purifier.

Positives of the CR Rating System

• Testing air purifiers within a controlled environment allows Consumer Reports to introduce into the testing process changeable variables that can simulate the various causes of allergy and asthma symptoms.
• Taking measurements and documenting them during the testing process.
• Purchasing products to test from retail establishments and not revealing its intended purpose to any manufacturer to avoid bias.
• Providing consumers with air qualilty tips to try before purchasing an air purifier.
• Listening to the air purifier industry’s suggestions for better testing protocols and sometimes responding to those suggestions.

Although Consumer Reports has accomplished positive milestones over the years, they did encounter a few stumbles along the way.

Complaints Against the CR Rating System

• When IQAir issued a press release in 2007 condemning Consumer Reports testing protocols as unacceptable and lacking in-depth comparisons, this caused a few others to come forward with similar claims.
• Lisa Whiting, an asthma advocate, blamed Consumer Reports for endangering the life of her son by providing misleading air purifier test results.
• Barry Cohen, the owner of Absolute Air Cleaners and Purifiers, Inc, complained that Consumer Reports only tests lower-quality room air cleaners and not any higher-quality ones.

In the United States alone, consumers have spent more than $500 million dollars a year on the purchase of air purifiers, hoping they will provide some form of relief from allergy and asthma symptoms. Although there is little medical evidence that confirms a room air cleaner can do this alone, an air purifier is still a much sought after product. As a result, Consumer Reports continues to test these appliances and publish its findings every three years and remains a primary source for objective results.

Through the many accusations and lawsuits, followed by the triumphs of credible explanations and test protocol revisions, Consumer Reports has continued to position itself as a trusted and reliable organization that looks out for the fairness and safety of the public. 

Consumer Reports’ Historical Air Purifier Ratings

Listed below are the highlights from Consumer Reports air purifier ratings that are published every 3 years.  We included recommended models, the most recent do not buy warnings, and links to the full results for older ratings.  For the most complete and up to date information, you can purchase an online subscription to Consumer Reports for $26 a year and gain access to the full ratings of 20 select room air purifiers and 2 whole house systems.

September 2010 Summarized Results

CR Recommended Portable Air Purifiers

• Whirlpool AP51030K – Overall score: 74/100, Estimated yearly cost in energy and filters: $208
• Hunter 30547 – Overall score: 73/100, Estimated yearly cost in energy and filters: $193

Models With a “Don’t Buy” Warning

• LightAir IonFlow 50F Surface – ineffective in removing contaminants

Other Models Rated In This Issue

• GE AFHC32AM
• Blueair 503
• Blueair 650E
• Hunter 30582
• Holmes HAP756-U
• Airgle 750
• Honeywell 50250
• FilterStream AirTamer A710
• 3M Filtrete Ultra Clean Air Purifier FAP03-RS
• Kenmore Plasmawave 85450
• Idylis IAP-10-280
• Amway Atmosphere 101076
• Therapure TPP250
• Vollara FreshAir HEPA US40726B
• Sanyo Air Washer ABC-VW24A
• Germ Guardian AC5000B
• Holmes HAP1200-U
• Oreck Proshield Plus AIR12GU

December 2007 Summarized Results

CR Recommended Portable Air Purifiers

• Whirlpool Whispure AP45030S – Overall Score: 63/100
• Kenmore Progressive 83202 – Overall Score: 57/100

Consumer Reports Complete December 2007 Air Purifier Ratings (PDF)

October 2005 Summarized Results

CR Recommended Portable Air Purifiers

• Friedrich C-90A – Overall Score: Good/Very Good
• Kenmore 83202 – Overall Score: Good/Very Good

Consumer Reports Complete October 2005 Air Purifier Ratings (PDF)

Air Purifiers That Help and Those That Don’t

Indoor air pollution is a serious health hazard that needs to be addressed. For those concerned with reducing harmful pollutants in their homes, air purifiers, along with controlling the sources of pollution and ensuring adequate ventilation, can help keep these unhealthy chemicals and objects down to a minimum. However, not all indoor air purifiers are created equal. Some are more effective than others, and some, unfortunately can cause bigger air quality problems than they solve.

“Ozone is a toxic gas with vastly different chemical and toxicological properties from oxygen.” – United States Environment Protection Agency

Smart buyers will research the effectiveness of the various types of air purification systems available on the market. This article will focus on one specific problem that some kinds of “purifiers” produce: ozone. Some companies produce air cleaners that deliberately introduce significant quantities of ozone into your home. But ozone is an extremely unhealthy substance that can cause significant health problems for people who are exposed to it. If pumping a pollutant into the air to counteract pollutants sounds odd to you, you’re right.

The purpose of this article is to explain why, if you are shopping for an effective, high-quality air cleaner, you should not purchase any air filter that generates ozone. First we will discuss ozone: what it is, and what effects the Environmental Protection Agency has found it can have on the human body.

What is Ozone?

Ozone is a molecule that is made up of three oxygen atoms. Therefore it is often abbreviated as O3, and you will occasionally hear it called “trioxygen.” Many people will be familiar with the term “ozone” from hearing about the ozone layer that exists in the earth’s stratosphere. Up there, some ten or more miles above the planet’s surface, ozone is helpful to humans; it serves to block out harmful radiation emanating from the sun. In fact, without it, life as we know it would not be possible. One sometimes hears of ozone holes, where the ozone has been depleted and radiation enters the atmosphere in higher than normal levels.

(structure of an ozone molecule, 3 oxygen atoms and their charges – Image Source: Wikipedia)

Are Manufacturer Claims Legitimate?

The impression people receive is that ozone is a beneficial substance, and, as far as the ozone layer goes, that is certainly the case.  Manufactures of ozone-generating devices play on this perception, as well. They may also use enticing terms like “energized oxygen” to describe ozone as just another form of the oxygen we breathe. However, chemistry just doesn’t work like that: to quote the EPA’s report “Ozone Generators that Are Sold as Air Cleaners,” ozone is “a toxic gas with vastly different chemical and toxicological properties from oxygen.”

However, someone who is only informed about the role ozone plays in shielding us from radiation may think of ozone solely in terms of its benefits and not be aware of the dangerous results that close contact with it can have. It is possible to speak of “good” ozone and “bad ozone,” but the only difference between the two is location. If you are breathing it, it is always the bad kind. In other words, when it comes to ozone, the EPA wants us to remember the slogan “good up high, bad nearby.”

“At ground level, ozone is a harmful pollutant.” – Environmental Protection Agency

Ozone is released by many pollution sources, such as car exhaust, chemical plants, and refineries, and is one of the substances monitored by the EPA under the Clean Air Act. The last thing you need is a so-called air purifier that pumps such a chemical directly into your home’s air.

Next, we will briefly discuss what it is about ozone that makes it so bad for your health.

Why is Ground-Level Ozone Unhealthy?

As we said above, ozone consists of three oxygen atoms that have bonded together. Usually when we speak of “oxygen,” we do not refer to a single oxygen atom but rather a molecule made up of two oxygen atoms, O2. It is this form of oxygen that humans and animals need to stay alive. This is because oxygen atoms naturally tend to bond with each other. A molecule consisting of two oxygen atoms is stable; the two atoms are tightly bound together and are not easily separated.

Ozone Bonds to Your Lungs

This is not the case with ozone. The third oxygen atom can become detached relatively easily, leaving instead one normal oxygen molecule with two atoms, and a single oxygen atom that is not bonded to anything else. It is this tendency to decay that makes ozone so dangerous.

Single oxygen atoms “want” to bond to something else, so to speak, and they will not only do so with one another. They can also attach themselves to organic compounds, such as those found in your body. When they do so, this completely changes the properties of whatever the oxygen atom has bonded with. The final result of the process for you, if you inhale ozone, is damage to the matter that makes up your body. This is why the EPA states that, however necessary ozone is in creating the conditions that allow life on Earth, “at ground level, ozone is a harmful pollutant.”

In short, by breathing the air in an ozone-rich environment, you are ingesting a substance that will wreak havoc on your lungs. Now let us take a look at the specific problems that arise when you are exposed to ozone.

The Negative Health Effects of Ozone

Breathing in ozone can damage your lungs and have a number of ill consequences. The following list is based on the EPA’s findings regarding the health effects of ozone exposure:

1. Causes Coughing –  Ozone can make you cough, irritate your throat, leave you short of breath, and cause aching in your chest, even in relatively low doses.
2. Inflames Your Lungs –  It can damage your respiratory system by inflaming the cells that line your lungs.
3. Possible Permanent Lung Damage –  It can cause permanent damage to the lungs themselves in some instances. For example, if a child is exposed to ozone, it can interfere with the growth and development of the lungs. In adults, it can accelerate the deterioration of the lungs that comes naturally with aging.
4. Worsens Asthma – If someone with asthma inhales ozone, it can worsen his or her condition even further.
5. Worsens Emphysema and Bronchitis – Likewise, ozone can exacerbate other lung diseases as well, including emphysema and bronchitis.
6. Interferes With Immune System –  It can interfere with the functioning of the body’s immune system around the lungs, leaving you more vulnerable to airborne infections because your body is less capable of fighting them off.
7. Damage Continues – Some of the immediate irritation caused by ozone may subside after a few days of exposure, even if you are still inhaling it at the same levels. Though this might feel like a relief, it can lull us into a false sense of security. The EPA pamphlet “Ozone and Your Health” (PDF) states that “ozone continues to cause lung damage even when the symptoms have disappeared.”

As you can see, it would be wise to take care to avoid ozone whenever possible. But if ozone is so unhealthy, why do some air purification manufacturers make products that deliberately introduce it into your home? We will now move from discussing ozone in general to examining the effectiveness and safety of these systems.

Ozone-Generating Air Purifiers: Do They Work?

The idea behind air cleaners that produce ozone is based on ozone’s reactive properties. As we said earlier, ozone is highly unstable and will break apart, leading to further chemical reactions. Makers of ozone generators suggest that this process will destroy many of the unhealthy airborne chemicals in your home. But the EPA, which has done considerable investigating into the effectiveness of ozone generators, disagrees, and lists three problems with these claims.

Ozone Air Purifiers Are Largely Ineffective

1. Many pollutants are not damaged by ozone – The EPA goes so far as to say in “Ozone Generators that Are Sold as Air Cleaners” that “for all practical purposes, ozone does not react at all with such chemicals.” Ozone may quickly damage you, but that does not mean everything is equally vulnerable to it.
2. Creation of new pollutants – When it comes to those things that ozone does neutralize, the reaction that destroys the original pollutant sometimes just creates new pollutants, leaving the air hardly any cleaner than it was before. One report prepared by the EPA suggests, for example, that “ozone is also believed to react with acrolein, one of the many odorous and irritating chemicals found in secondhand tobacco smoke.”
3. Ineffective Particle Removal – Ozone does not do anything about unhealthy particles in the air that comprise a good deal of the total amount of indoor air pollution. This would include pet dander or dust, for example. Traditional air filters are usually most effective at getting rid of particulate pollution, which means that if someone buys an ozone generator instead, he or she is missing the opportunity to do something significant to reduce pollution.

Beyond these points, further studies cited by the EPA have also indicated that ozone generators do nothing against many odor-causing substances commonly found in the home. One report, published in the official journal of the American Society of Heating, Refrigerating, and Air Conditioning Engineers, found that “body odor may be masked by the smell of ozone but is not removed by ozone.”

Also, although there does exist some evidence indicating that ozone can be used to combat viruses and living pollution sources such as bacteria and mold, for this to have any measureable impact, the ozone would need to be present in qualities far above what humans can safely tolerate.

To sum it all up, ozone generators just don’t work. That alone is enough reason to avoid buying them, of course. But on top of that, there is the question of safety, and on these grounds, as well, ozone generators fail.

Ozone-Generating Air Purifiers: Are They Safe?

In fairness, different kinds of ozone generators produce different amounts of ozone. Some, if used exactly as recommended by the manufacturer, may not create enough ozone to cause any damage. For all the reasons discussed in the previous section, these purifiers are still useless as a means of cleaning the air, but at least they aren’t directly contributing to the problem they are advertised as solving.

Unfortunately, the EPA has found that, with some other brands of ozone-generating devices, “concentrations of ozone considerably higher than [recognized public health standards] are possible even when a user follows the manufacturer’s operating instructions” to the best of his or her ability. There are simply too many factors that can spring up and cause an increase in ozone exposure. The size of the room, whether doors or left open or closed, and the exact makeup of the air around the ozone generator all affect how concentrated the ozone will become.

Also, it is very difficult to take into account other sources of ozone (cars, factories, etc.) that may be nearby. It is possible that an ozone generator will not on its own produce enough ozone to be harmful, but when combined with these other sources, the amount of ozone crosses the danger threshold.

In conclusion, even if ozone generators did work as they are intended to do, and as they are marketed as doing, they just are not safe enough to put in your home.

What Are the Alternatives to Ozone Air Purifiers?

All the evidence indicates that ozone generators are neither effective nor safe. Therefore, first of all, if there are any ozone-generating devices in your house, turn them off at once. They are at best doing no good, and at worst they are adding to the pollution that you purchased them to reduce.

If you are concerned about indoor air quality, the good news is that there are plenty of air purification systems available for houses and apartments that do not produce any ozone at all. There are much better and safer methods of eliminating toxins from the air, and the EPA acknowledges that some other kinds of air purifiers have a role to play in cleaning up the air you breathe at home.

Mechanical Air Purifiers The Best Choice

“Mechanical” air purifiers are those that use filters to capture particles that would otherwise float in the air, possibly to be inhaled by humans. These are likely to be the smartest choice, but be aware that they will not help against gaseous pollutants, only solid ones, especially smaller particles that remain in the air for an extended period of time. Even with a good air purifier, controlling the sources of pollution and making sure your home is well-ventilated are necessary steps.

Note that there are also electronic air purifiers, such as ionizers. However, these are not recommended because they, too, produce ozone, whether they were intended to do so or not. To take the most famous example, the makers of the well-known Ionic Breeze brand of purifiers eventually went bankrupt due to reports that their product produced high levels of ozone. Therefore, mechanical filters will be the best option for most people.

Summary and Conclusion

Ozone, a molecule consisting of three oxygen atoms, may help preserve life on earth when it is up in the stratosphere, but it also poses health risks for people when they inhale it. Although some companies sell “air purifiers” that supposedly fight toxic chemicals in the air with ozone, the truth is that these devices are ineffectual and sometimes downright dangerous. They can contribute to lung diseases, worsen pre-existing problems, and damage lung tissue. With so many potential health hazards floating around in your home’s air, the last thing you need is add ozone into the mix.

Therefore, such devices should be avoided in favor of air filtration systems that do not produce ozone. A high-quality air purifier, operating on sound scientific principles, is an important weapon in the fight against indoor air pollution. And happily, there are good, effective air purifiers readily available to keep your home’s air breathable.

Bottom Line – Before you purchase an air purifier, make sure that it does not produce ozone!

List of California Approved Air Purifiers (No Ozone Generated During Operation)

Brand Model Name (Model Numbers) Date Notified EO Number Filtrete™ Ultra Quiet Room Air Purifier (FAP01-RS)  Mechanical 02-26-2009 G-09-004 Filtrete™ Ultra Clean Room Air Purifier (FAP-02, FAP02-RC, FAP02-RS, FAP02-RY, FAP-03, FAP03-RC, FAP03-RS, FAP03-RY) Mechanical 02-26-2009 G-09-004 Filtrete™ Ultra Quiet Room Air Purifier (FAP00-RS)  Other* 12-02-2009 G-09-118 Aerus (Blueair AB) Guardian Air Other* 05-12-2010 Air King® 42″ Wind Curve (9554) Other* 11-12-2009 G-09-102 48″ Tower Fan (9820, 9820A) Other* 11-12-2009 G-09-102 Atmosphere (Access Business Group) Atmosphere™ Air Purifier (101076) Mechanical 04-27-2009 G-09-014 Blueair AB Blueair (403, 450E, 503, 550E, 603, 650E) Other* 05-12-2010 Blueair (203, 270E) Other* 07-09-2010 Electrolux (Winix) EL500A Mechanical Pending** EL500AX EL500AZ Other* Pending** Febreze®/True Air (Hamilton Beach) Direct Plug-In Odor Eliminator (04530C, 04530F, 04531C, 04531F) Mechanical 12-17-2009 G-09-103  GE (Woongjin Coway) Small Air Purifier (AFHC09AM) Mechanical 05-04-2009 G-09-015 Large Air Purifier (AFHC21AM) Mechanical 05-04-2009 G-09-015 Super Air Purifier (AFHC32AM) Mechanical Pending** Holmes (Jarden Consumer Solutions) HAP9240-U  HAP9412-U HAP9424-U Mechanical 03-16-2010 Honeywell® by Kaz® enviracaire® Programmable True HEPA Air Purifier (50310, 50311) Mechanical 03-20-2009 G-09-006 enviracaire® True HEPA Air Purifier (50100, 50101, 50150, 50200, 50250, 50251, 50300, 50300-CST) Mechanical 03-20-2009 G-09-006 enviracaire® QuietClean (60001 ) Other* Pending** HEPA-Type Tabletop Air Purifier (16200) Other* Pending** HEPAClean Compact Tower (HHT-055) Mechanical 06-01-2010 HEPAClean Tower (HHT-155) Mechanical 06-01-2010 HEPAClean Air Purifier Dual Pack (HHT-1500) Mechanical 06-01-2010 HEPAClean Tabletop Air Purifier (HHT-011) Other* Pending** HEPAClean Tower Air Purifier (HHT-080, HHT-081) Other* 07-28-2009 G-09-006 HEPAClean Tower Air Purifier (HHT-085-HD) Other* 03-23-2010 G-10-014 HEPAClean UV Tower Air Purifier (HHT-145, HHT-149,  HHT-149-CST) Other* 07-28-2009 G-09-006 HEPAClean UV Tower Air Purifier (HHT-149-HD) Other* 03-23-2010 G-10-014 Pet Clean Air Air Purifier (HHT-013, HHT-016-MP) Mechanical Pending** QuietCare™ True HEPA Air Purifier   (17007, 17007-HD) Mechanical 01-27-2010 QuietCare™ True HEPA Air Purifier   (17200, 17205, 17205-CST) Other* 01-27-2010  G-10-014 QuietCare™ True HEPA Air Purifier with permanent filter (17000, 17000-19, 17000-S, 17000BB, 17005, 17006, 17000N-KOL) Mechanical 03-20-2009 G-09-006 QuietCare™ True HEPA Air Purifier with permanent filter (17005-S) Mechanical 08-12-2009 G-09-006 QuietClean Air Purifier (HFD-015, HFD-1101, HFD-110, HFD-112, HFD-116C ) Other* 06-30-2009 G-09-006 QuietClean Air Purifier (HFD-135, HFD-137, HFD-139) Other* Pending** QuietClean Air Purifier with permanent filter (HFD-120-Q, HFD-120-Q-1) Other* 05-29-2009 G-09-006 QuietClean Air Purifier with permanent filter (HFD-122C, HFD-015C) Other* 10-19-2009 G-09-101 QuietClean Antibacterial Air Purifier (HFD-130) Other* Pending** QuietClean Compact Tower Air Purifier (HFD-010) Other* Pending** QuietClean Tower Air Purifier (HHT-090) Other* 03-04-2010 G-10-014 QuietClean Tower Air Purifier (HFD-123-HD) Other* 03-23-2010 G-10-014 QuietClean UV Tower Air Purifier (HHT-215, HHT-217, HHT-219) Other* Pending** SilentComfort™ True HEPA Air Purifier (18155, 18150) Mechanical 03-20-2009 G-09-006 True HEPA Air Purifier (50255-HD) Mechanical 03-23-2010 G-10-014 True HEPA Air Purifier with permanent filer (50150-S, 50250-S) Mechanical 10-19-2009 G-09-101 True HEPA Compact Tower (HPA-050) Mechanical 06-02-2010 True HEPA Tower (HPA-150) Mechanical 06-02-2010 Hunter Fan HEPAtech Air Purifier System (30054, 30055, 37055) Mechanical 06-30-2009 G-09-005 HEPAtech   (30057,30059, 30710, 30711, 30730, 30748, 30750) Other* Pending** Permatype Air Purifier  (30835, 30836, 30837) Mechanical Pending** Programmable HEPA Air Purifier (30401) Mechanical 06-30-2009 G-09-005 QuietFlo® HEPA Air Purifier (30245) Mechanical 06-30-2009 G-09-005 QuietFlo® HEPA Air Purifier (30525) Mechanical 03-16-2009 G-09-005 QuietFlo® Plus Air Purifier (30785, 30780 to 30789) Mechanical 06-30-2009 G-09-005 QuietFlo® True HEPA Air Purifier (30090, 30095) Mechanical 03-16-2009 G-09-005 SOLO2 (30030 to 30039, 30040 to 30049, 37030 to 37039 ) Mechanical 06-30-2009 G-09-005 IDYLIS (Woongjin Coway) Air Purifier (IAP-10-100, IAP-10-100C, IAP-10-125, IAP-10-125C, IAP-10-150, IAP-10-150C, IAP-10-200, IAP-10-200C, IAP-10-280, IAP-10-280C) Mechanical Pending** IQAir® Cleanroom H13™ (1EB UD0 KGU / 1EB UD0 KGB) Mechanical 04-15-2010 Dental Hg™ (1D0 UA0 IGU, 1DA UA0 IGU) Mechanical 04-15-2010 Dental Pro™ (1D0 UA0 IGU, 1DB UA0 IGU) Mechanical 04-15-2010 GC™ AM (1C0 UB0 HGU, 1CA UB0 HGB) Mechanical 04-15-2010 GC™ ChemiSorber (1C0 UB0 HGU, 1CB UB0 HGB) Mechanical 04-15-2010 GC™ MultiGas (1C0 UB0 HGU, 1CC UB0 HGB) Mechanical 04-15-2010 GC™ VOC (1C0 UB0 HGU, 1CD UB0 HGB) Mechanical 04-15-2010 GCX™ AM (1F0 UB0 LGU, 1FA UB0 LGB) Mechanical 04-15-2010 GCX™ ChemiSorber (1F0 UB0 LGU, 1FB UB0 LGB) Mechanical 04-15-2010 GCX™ MultiGas (1F0 UB0 LGU, 1FC UB0 LGB) Mechanical 04-15-2010 GCX™ VOC (1F0 UB0 LGU, 1FD UB0 LGB)  Mechanical 04-15-2010 HealthPro® (1BA UA0 CGU) Mechanical 04-15-2010 HealthPro® Compact (1AG UA0 RGU) Mechanical 04-15-2010 HealthPro® Compact Plus (1AH UA0 VGU) Mechanical 04-15-2010 HealthPro® Plus (1BB UA0 DGU) Mechanical 04-15-2010 Lasko Products® 42″ Wind Curve™   (2551, 2554) Other* 11-12-2009 G-09-102 48″ Tower Fan (4820, 4822) Other* 11-12-2009 G-09-102 Cyclonic Ceramic Heater (5840, 760000, 6000) Other* Pending** LifeWise Compact Tower Air Purifier (63-1533) Other* Pending** QuietClean Air Purifier (63-1532) Other* 06-30-2009 G-09-006 Oreck   Professional Air Purifier (AIRT, AirTB) Other* 04-22-2010 G-10-038 ProShield Air Purifier (AIR12B, AIR12GU) Other* 03-10-2010 G-10-038 Rexair, LLC Rainbow (E2 Type 12) Mechanical 02-01-2010 G-10-015 RainMate Air Freshener (AP-2) Mechanical 02-01-2010 G-10-015 Sharp® Air Purifier (FP-P30U, KC-830U) Other* 03-23-2010 G-10-036 Air Purifier (KC-850U) Other* 06-23-2010 Portable Air Conditioner (CV-P10RC) Other* Pending** SwissAir™ (IQAir North America) SolventMaster JV3 (1S0 UB0 000 / 1S0 UB0 PGT) Mechanical 04-15-2010 True Air® (Hamilton Beach) Air Decor Air Purifier (04995) Mechanical 01-06-2010 G-09-103 Direct Plug-In Odor Eliminator (04530, 04531) Mechanical 12-17-2009 G-09-103 Direct Plug-In Odor Eliminator (04530G) Mechanical 04-23-2010 Direct Plug-In Odor Eliminator (04530GM, 04531GM) Mechanical 06-07-2010 EcoClean Air Purifier (04493) Other* 07-29-2010 Pet Air Purifier (04493P) Other* 07-29-2010 Room Size Odor Eliminator (04532) Mechanical 11-23-2009 G-09-103 Room Size Odor Eliminator (04532GM) Mechanical 04-23-2010 Tower Allergen Reducer (04384) Mechanical 04-23-2010 Tower Allergen Reducer (04383) Mechanical 11-23-2009 G-09-103 UTLT+ (CCL Products Limited) Electrostatic Air Cleaner (AP-360) Other* 03-03-2010 G-10-037 Vicks (Kaz) V9070 V9071 Other* Pending**

(Source: State of California, list approved December 2009 – http://www.arb.ca.gov/research/indoor/aircleaners/certified.htm)

Sources referred to in this article:

• United States Environmental Protection Agency. “Ozone and Your Health.” http://www.airnow.gov/index.cfm?action=ozone_health.index
• — . “Ozone Generators That Are Sold as Air Cleaners.” http://www.epa.gov/iedweb00/pubs/ozonegen.html
• — . “Ozone – Good Up High, Bad Nearby.” http://www.epa.gov/oar/oaqps/gooduphigh/
• — . “Residential Air Cleaners (Second Edition): A Summary of Available Information.” http://www.epa.gov/iedweb00/pubs/residair.html
• State of California: Certified Air Cleaners http://www.arb.ca.gov/research/indoor/aircleaners/certified.htm
• Wikipedia. “Ozone.” http://en.wikipedia.org/wiki/Ozone
• — . “Ozone Layer.” http://en.wikipedia.org/wiki/Ozone_layer

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Introduction

Indoor air pollution can be a serious health risk. Studies by the Environment Protection Agency have shown that the air inside buildings is often two to five times more polluted than the air outside, and sometime much more.

One thing we must keep in mind is how many different sources of pollution can contribute to lowering the air quality of our indoor spaces. The term “indoor air pollution” is an umbrella which covers a wide array of unhealthy material which can have different effects on the human body. This article will examine (in no particular order), the ten most common sources of air pollution in American homes, as identified by the U.S. Consumer Product Safety Commission (CPSC). For each item, we will focus on three things: what these pollutants are and where they come from, what health effects they have on humans, and how you can deal with them so that your home is as pollution-free as possible.

CPSC recommends stopping the sources of indoor air pollution as the first strategy to keep the air clean in your home. The second is improving ventilation in your home, so that the following toxins do not stay trapped inside. The third is making use of quality air purification devices.

Most of the information below is based on material provided by the Environmental Protection Agency (EPA) or the CPSC.

1. Radon

(Source:Wikipedia.  Author: Greg Robson)

Radon is a highly radioactive gas that can be introduced into the home through the ground beneath it, well water, and the building materials that constitute your house or apartment. Part of what makes radon so dangerous is the fact that it is colorless, tasteless, and odorless, and that it produces no immediate symptoms, which means that you will normally be completely unaware that you are inhaling it. The CPSC states that one study has indicated that radon is over three times as prevalent in homes as in the outdoors.

Inhalation of radon is linked to lung cancer, and the CPSC estimates that it causes between 7,000 and 30,000 lung cancer deaths every year. For smokers, radon exposure increases the risk of cancer even further, as radon can attach itself to the smoke and lodge itself in the lungs.

Fortunately, testing for radon is relatively inexpensive and easy to do using readily available radon testing kits. It is a good idea to test your home, and if radon levels are higher than 4 pci/L, take steps to reduce it. Contact a professional to help you.

Air purifier effectiveness – None.  Radon must be vented to the outdoors.

2. Environmental Tobacco Smoke (Secondhand Smoke)

The chemicals that resulting from smoking will remain in the air after the cigareete has been finished.

The health risks of smoking are too well known to need any in-depth discussion here. Environmental tobacco smoke carries risks similar to that caused by directly smoking. These include lung cancer and heart disease as well as irritation of the eyes nose etc. It can also exacerbate asthma and cause other health problem.

This is one source of pollution that is very easy to control: simply don’t smoke inside your home or let others do so. By choosing to keep your home smoke free, you can eliminate one major source of indoor air contamination entirely.

Air Purifier Effectiveness – Medium.  Many air purifiers successfully remove a portion of tobacco smoke from the air.  Effectiveness varies by model.

3. Biological Sources

(Image Author: Infogramation)

Remember that you are not the only life form that calls your house or apartment home. From pets, to insects, to mold and mildew, all the living things around you make their own contributions to the pollution in your air.

Biological pollutants can cause irritation of the eyes and nose and asthma. There are plenty of reasons you don’t want bugs, mold, or mildew infesting your home; their contribution to air pollution should be one of them.

Unlike environmental tobacco smoke, there is no way to completely rid your home of this pollution source. But you can still take some simple steps to reduce it. Moisture encourages the growth of mold and mildew, for instance, so minimize moisture by making sure you have no leaks and using exhaust fans and ventilators if you have them. Be sure to dust and vacuum regularly as well. Wash your bedding in hot water to kill the mites that like to make their home there, and wash your rugs as well. Keep your home clean in order not to attract cockroaches and other pests. One caution to keep in mind: try to avoid using chemical pesticides when other means of pest control are available, as pesticides themselves are a source of indoor air pollution as well (see #9 below.)

Air Purifier Effectiveness – Minimal.  Some airborne mold particles may be captured but mold must be removed at the source where it grows.

4. Carbon Monoxide

Like radon, carbon monoxide (CO for short) is colorless, tasteless, and odorless, and therefore particularly insidious. Environmental tobacco smoke is one source of CO, but there are many others, including gas stoves and heaters, wood stoves, chimneys, and furnaces. Automobiles also produce CO, so attached garages increase the risk as well.

CO attacks, among other things, your bloodstream and central nervous system. Exposure to low-level doses of carbon monoxide will leave you feeling sluggish, which means an inexplicable lethargy is a good early warning sign. Heavier levels of ingestion can cause nausea, dizziness, headaches, and a lack of coordination. Carbon monoxide is fatal when you come into contact with too much of it.

Keeping the CO sources listed above in proper working order and well ventilated will reduce the risk of CO poisoning. Also, you should install CO detectors in your house or apartment; they are cheap and easy to find and should be a standard accessory in every home.

Air Purifier Effectiveness – None.  Sources of CO2 pollution must be eradicated.

5. Nitrogen Dioxide

(Image author: SJu)

Nitrogen dioxide (NO2) comes from many of the same sources as carbon monoxide and carries with it similar health risks. In addition, it can also help produce another very dangerous chemical, ozone. Unlike CO, however, NO2 possesses a sharp and easily detectable smell and a reddish-brown color.

Reducing NO2 can be done using the same methods recommended to reduce CO. Since it is more easily detectable than radon or carbon monoxide, even without the aid of any equipment, it poses less of a threat, but you should never take anything for granted when it comes to a deadly chemical like this one.

Air Purifier Effectiveness – None.  Sources must be eliminated or reduced to safe levels.

6. Organic Gases

“Organic gases,” or “volatile organic compounds” (VOCs), is something of a catch-all term for gases that are emitted from many different sources. Among the common sources for VOCs identified by the EPA are paint, cleaning supplies, pesticides, glue, printers and photocopiers, permanent markers, and certain building materials. As you can see, your home probably has many VOC sources, so being aware of them is important.

The effects of organic gases are likewise various, and range from irritation of the eyes, nose, and throat to dizziness and nausea to even more serious problems, including cancer and damage to the central nervous system. Different gases have different levels of toxicity.

One way to limit the concentration of VOCs in your home is to store VOC-producing material outside when possible. Do not buy unnecessarily large quantities of things like cleaning supplies, so that they are not sitting unused in your home giving off gases. Also, use them in ventilated areas when you can and always follow manufacturer’s instructions—often they are there to help limit you exposure to the gases.

Air Purifier Effectiveness – Minimal.  Some air purifiers can trap VOC particles but they must had the filtration system to accommodate, most don’t.

7. Respirable Particles

Respirable particles are simply small bits of matter that can easily be inhaled (“respire” is another word for “breathe”). Environmental tobacco smoke contributes to their presence, as do fireplaces, kerosene heaters, and wood stoves.

Respirable particles, like many other indoor air pollutants, can irritate the eyes, nose, and throat, and they can also cause ailments such as bronchitis. They are a cause of cancer as well.

Reducing their presence can be accomplished by proper maintenance of the devices that cause them, by ensuring good ventilation, and by not smoking indoors. Homes without the sources listed above rarely have significant levels of repairable particles, so long as they are well ventilated.

Air Purifier Effectiveness – Medium-High.  Depending on the model, some air purifiers are quite effective at removing particles from the air.

8. Formaldehyde

(Image Author: Simon Eugster)

Formaldehyde, or CH2O, is an organic compound that exists as a gas at room temperature. Formaldehyde is invisible, but has a distinctive pungent smell. Common sources of formaldehyde in the home include glues, environmental tobacco smoke, and textiles such as durable press drapes. But the top source of formaldehyde in most people’s homes is the presence of pressed wood containing urea-formaldehyde resins in building materials and furniture: this category includes particle board, hardwood plywood paneling, and, above all, medium-density fiberboard. Homes built in the 1970s were sometimes insulated with urea-formaldehyde foam insulation (UFFI), which is a major source of indoor formaldehyde pollution.

In high enough concentrations, formaldehyde can cause irritation of the eyes, nose, and throat, coughing, rashes, and fatigue. It may also be a cause of cancer and other serious health problems.

If you do not have UFFI as insulation in your home, you probably do not have excessive levels of formaldehyde. To keep formaldehyde at a minimum, reduce the humidity and moderate the temperature in your home. In the future, use exterior-grade pressed wood products, which release less formaldehyde because they have different resins.

Air Purifier Effectiveness – Minimal-None.  Some air purifiers can remove a small amount gases but sources of formaldehyde pollution must be removed.

9. Pesticides

Pesticides’ very purpose is to kill, so clearly, you do not want to be continuously inhaling them at home. Pesticides release a variety of chemicals into the air. Pesticide containers in the home are the primary source of this pollutant, but pesticide can also be unwittingly tracked in from the yard by those who use them outside.

Pesticides can irritate the eyes, nose, and throat, and they are detrimental to the central nervous system and the kidneys. They are also associated with an increased risk of cancer.

To reduce the pesticides in your indoor environment, avoid using chemical pesticides when possible. If you do need to use them, follow instructions on the label, do not use excessive amounts, and make sure you keep the area well ventilated after use. Do not purchase more than you need, so that you don’t have extra pesticides resting unused in your home giving off fumes. It is best to store pesticides outside rather than inside. If you need the services of a pest-control company, check its credentials before you allow it to spray harmful chemicals in your house.

Air Purifier Effectiveness – Minimal-None.  Pesticide sources should be stored outside the home.

10. Asbestos

Finally, asbestos is a type of magnesium silicate fiber that was once commonly used in home construction for its ability to insulate the home and resist fire. Asbestos fibers are so small that they can easily be inhaled by someone without the person knowing it. Today, many forms of asbestos are banned by the federal government, and even those that are not are rarely used. Therefore, asbestos is a major risk in older homes rather than newer ones.

Asbestos produces no immediate symptoms, so there are no early-warning signs. In the long term, it can contribute to abdominal cancer, lung cancer, and mesothelioma. There is even a condition known as asbestosis, which occurs when the fibers cause scarring in the lungs.

If your home has asbestos, this does not necessarily mean that you are in danger. If the asbestos is of good quality and left undisturbed, it will not release fibers into the air to be inhaled. If some operation needs to be performed on your home that might lead to the asbestos being disturbed, it is best to use professionals. If you are worried about asbestos levels in you home, the wise action may be to seal the asbestos off rather than try to remove it, which may just lead to more asbestos being released into the air.

Air Purifier Effectiveness – Varies.  Many air purifiers can filter asbestos particles suspended in the air column down to .3 microns.  However, asbestos sources should be removed by experts and surfaces cleaned if asbestos contamination is suspected.  Should never rely on an air purifier alone to deal with asbestos pollution.

Conclusion

As you can see, although there are numerous sources of indoor air pollution, many of them can be fought using relatively simple steps. Also, some actions will help to reduce multiple sources: keeping humidity in your house or apartment low, for example, and not storing excess chemical products inside. By being aware of the dangers and following the advice above, you may significantly improve the quality of the air you breathe at home. Remember also to ensure good ventilation, so that the sources you can’t completely eliminate will not stay trapped inside.

Sources referred to in this article:

• Green Facts. “Scientific Facts on Air Pollution: Nitrogen Dioxide.” http://www.greenfacts.org/en/nitrogen-dioxide-no2/index.htm
• United States Consumer Product Safety Commission. “The Inside Story: A Guide to Indoor Air Quality.” http://www.cpsc.gov/cpscpub/pubs/450.html#Refguide
• — . “Biological Pollutants in Your Home.” http://www.cpsc.gov/cpscpub/pubs/425.html
• United States Environmental Protection Agency. “Indoor Air Quality Tools for Schools.” http://www.epa.gov/iaq/schools/pdfs/publications/training/short_ppt.pdf
• — . “An Introduction to Indoor Air Quality: Asbestos.” http://www.epa.gov/iaq/asbestos.html
• — . “An Introduction to Indoor Air Quality: Formaldehyde.” http://www.epa.gov/iaq/formalde.html
• — . “An Introduction to Indoor Air Quality: Nitrogen Dioxide.” http://www.epa.gov/iaq/no2.html
• — . “An Introduction to Indoor Air Quality: Pesticides.” http://www.epa.gov/iaq/pesticid.html
• — . “An Introduction to Indoor Air Quality: Respirable Particles.” http://www.epa.gov/iaq/rpart.html
• — . “An Introduction to Indoor Air Quality: Volatile Organic Compounds.” http://www.epa.gov/iaq/voc.html
• Wikipedia. “Carbon Monoxide Poisoning.” http://en.wikipedia.org/wiki/Carbon_monoxide_poisoning
• — . “Formaldeyde.” http://en.wikipedia.org/wiki/Formaldehyde
• — . “Health Effects of Radon.” http://en.wikipedia.org/wiki/Health_effects_of_radon
• — . “Nitrogen Dioxide.” http://en.wikipedia.org/wiki/Nitrogen_dioxide

Introduction: Ultraviolet Light

Ultraviolet (UV) light is a form of radiation with very short wavelengths—too short to be perceived by the human eye. This form of energy is called “ultraviolet” because it has shorter wavelengths than violet light, which has the shortest waves of any kind of visible light.

Although UV radiation can be dangerous, and you can often hear reports about the dangers of UV rays coming from the sun, ultraviolet light is not always detrimental to humans and has a variety of uses. Some air purifiers include specialized lights that produce ultraviolet rays as a way to kill living pollutants.

EPA Studies – Effectiveness of UV Air Purifiers

Based on the available test information, the actual success rate of UV purifiers is mixed. According to the EPA’s official guide on indoor air cleaners, well-designed ultraviolet air cleaners are able to:

Air Purifiers

 

“[Air purifiers] reduce the viability of vegetative bacteria and molds and to provide low to moderate reductions in viruses but little, if any, reduction in bacterial and mold spores.”

Factors Influencing UV Air Purifier Effectiveness

It also states that various factors influence the effectiveness of UV purifiers, including

• UV irradiation dose
• System design and application
• System operation characteristics
• Microorganism targeted for deactivation.

Thus not all UV air purifiers are the same, and UV lights will be more or less useful depending on the environment they are placed in.

Furthermore, tests have shown that UV cleaning alone does not reduce dust mite problems or allergic reactions to mold—the latter because mold is still dangerous to humans even if it is dead. The Environmental Protection Agency states that the only solution to mold is to have it removed. Ultimately, the EPA declares that further testing is necessary in order to better understand just how useful ultraviolet air cleaners really are.

Conclusion – Ultraviolet Air Purification Effectiveness

• Well designed systems can reduce vegetative bacteria, molds, and some viruses
• Little if any reduction in bacteria or mold spores
• Ineffective against particles like dust or dust mites
• Further research is needed to measure absolute effectiveness

Sources referred to in this article:

• United States Environmental Protection Agency. “Residential Air Cleaners (Second Edition): A Summary of Available Information — Ultraviolet Germicidal Irradiation Cleaners.” http://www.epa.gov/iedweb00/pubs/residair.html#Ultraviolet_Germicidal_Irradiation_Cleaners
• Wikipedia. “Ultraviolet.” http://en.wikipedia.org/wiki/Ultraviolet