Ozone-producing air purifiers pose health risk

In a small, poorly ventilated room, an indoor air purifier that produces even a few milligrams of ozone per hour can create an ozone level that exceeds public health standards, researchers at UC Irvine have found.

Scientists also discovered that ozone produced by air purifiers adds to ozone already present in any room – a prediction that had never been experimentally verified in a realistic indoor environment.

“These results mean that people operating air purifiers indoors are more prone to being exposed to ozone levels in excess of public health standards,” said Sergey A. Nizkorodov, a chemistry professor in the School of Physical Sciences at UCI.

Nizkorodov and UCI chemistry students Nicole Britigan and Ahmad Alshawa published their research in the current issue of the Journal of the Air & Waste Management Association. Their findings will be studied by officials deciding how to regulate the distribution of indoor air purifiers.

California lawmakers are considering legislation that would require the California Air Resources Board to adopt regulations to reduce emissions from indoor air cleaners by 2008. The state board and the U.S. Environmental Protection Agency have issued advisories discouraging use of air purifiers, but the devices remain on the market because no agency has the outright authority to regulate how much ozone they produce.

Indoor air purification has gained widespread popularity with the surge in air pollution problems in urban areas.

Air purifiers target dust, pollen, airborne particles and volatile organic compounds, which are emitted by a wide range of products, including paint, cleaning supplies and pesticides. These pollutants are believed to aggravate respiratory and other health problems.

Indoor air purifiers are advertised as safe household products for health-conscious people – especially those who suffer from allergies and asthma – but some purifiers produce ozone during operation. For example, certain widely used ionic air purifiers, which work by charging airborne particles and electrostatically attracting them to metal electrodes, emit ozone as a byproduct of ionization.

Depending on the design, some ionic purifiers emit a few milligrams of ozone per hour, which is roughly equal to the amount emitted by a dry-process photocopier during continuous operation.

Ozone can damage the lungs, causing chest pain, coughing, shortness of breath and throat irritation. It can also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections – even in healthy people.

For this study, the research group tested several types of air purifiers for their ability to produce ozone at 40 percent to 50 percent relative humidity in various indoor environments, including offices, bathrooms, bedrooms and cars.

Placed inside a room, the air purifier was turned on, and the ozone concentration buildup was tracked until a steady level of ozone was reached. In many cases, indoor ozone levels far exceeded outdoor safety guidelines, which in California are 90 parts per billion for one hour and 70 parts per billion for eight hours.

The ozone level in some instances reached higher than 350 parts per billion – more than enough to trigger a Stage 2 smog alert if similar levels were detected outside. A Stage 2 alert last occurred in the Southern California coastal air basin in 1988.

Of the spaces tested, the largest increase in steady ozone levels occurred in small rooms with little ventilation, especially those containing materials that react slowly with ozone such as glossy ceramic tile, PVC tile and polyethylene, which is used in plastic. Ozone reacts quicker with materials such as carpet, cloth, rubber and certain metals, destroying itself in the process.

People who operate purifiers indoors are more likely to be exposed to ozone levels that exceed health standards because ozone from these devices adds to ozone that already exists in the room.

Said Nizkorodov: “If 30 parts per billion of ozone exist in the room because dirty outside air is leaking into the house, turning on an air purifier that generates 50 parts per billion of ozone creates a total ozone level of 80 parts per billion.”

From UC Irvine

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6 thoughts on “Ozone-producing air purifiers pose health risk”

  1. It seems low ozone emitting air purifiers are becoming ever more popular since reports of poor air quality have been popping up in the news… but how many of these companies are actually bonafied “environmentally green” companies. I have found only one in all of my searches.

    see the link… http://www.shaklee.net/healthybodyhealthymind/product/55102

    Shouldn’t a company that provides gadgets to clean the air make an attempt at aiding the solution at the industry level as well??

  2. If your looking for an air purifier that is 100% ozone and Ion free (which I would highly recommend) then try doing some research on the swiss made IQ Air. I searched high and low the the best air purifier being made world wide, and hands down the IQ Air was it. It filters out down to .003 microns, not just 0.3 microns like most everything else. In my research I discovered that nearly 90% of the particles we breathe are microscopic (smaller then 0.3 microns). I work in a specialized cleaning store and sell the IQ Air, I’ve also done lots of research on Ionic/Ion air purifers. Don’t Buy One! They don’t filter the air enough to worry with, and many people have been found to be very sensitive to the Ions they produce. They’ve even been known to cause major headaches. The IQ Air won’t produce a single ion or any ozone. It’ll also tell you when to change the filters inside, it has 3 and all last different lenghts of time.
    If you have any other questions about it just let me know!

  3. I see nothing on the website BiologyNews.net to suggest that it is a reputable website. First of all, who pays for and runs the site? Nothing on the site discloses that information as far as I can see. Also, I believe you misinterpreted the statement about the smog alert. The article is not claiming that ozone-generating air purifiers are responsible for the air pollution problem in Southern California. It -is- suggesting that people who use this type of air purifier in their homes are at a greater health risk due to ozone exposure. More information is available at the Environmental Protection Agency’s website at: http://www.epa.gov/iaq/pubs/ozonegen.html

    By the way: Just because a gas is colorless does not mean it isn’t harmful, just in case that’s what you’re suggesting. Take chlorine gas, for example. Not only is it colorless, it is deadly poisonous. Thoughts? Comments?

  4. HI, thanks for your comment on health risks, or lack there of, and ozone caused by air purifiers. I am looking for an air purifier for my toddlers room. A very old round heppa filter purifier was given to me and that is what I am using now. I don’t know how to tell when it needs replaced and hopefully there are no negative effects from using it now. I’m sure it needs a new filter and rather than buying one I am looking into a new purifier. Since you seem to be an expert— Do you know if it is only referring to ionic air purifiers? Are neg. ion producing air purifiers the same as ionic air purifiers and do they both release the same amount of ozone? Do other airpurifiers without ionic purification release ozone? Do you happen work with or be related in any way to an air purification company? Thanks for answering my questions, C

  5. Here are the facts. UCI received a $7.5 million dollar grant from the federal government to study air pollution. Ozone is a scapegoat for the real causes of smog, mainly older vehicles and factories that lack modern emissions controls. Hydrocarbons, VOC’s, and nitrous oxides create ozone when sunlight is added to the mix. Ozone is a clear gas. Smog is brown, coincidentally so is vehicle exhaust. It is reported that two out of three big rigs and buses in America are exempt from modern emissions controls. They are the real cause of smog. However, it would cost countless billions of dollars to replace them, so the politicians throw money at researchers like the people at UCI who come up with brilliant articles such as this one blaming ozone producing air purifiers for creating “smog like” conditions. Is this misinformation? Of course. Why? To distract people from the real culprits.

    I have a solution to the smog problem. Require that ALL vehicles and factories have emissions controls within 2 years. Within a year, someone will invent emission control devices for the older engines and factories that now cannot be fit. Why? That’s the way our economy functions. Right now, there is no need for such equipment, those older vehicles and factories are exempt you see. Watch how fast someone invents emission control devices for those older engines if it becomes mandatory! Worse case scenario, it can’t be done and the older engines have to be replaced with modern engines. Either way, the smog problems we have now would go way overnight if we took two thirds of the big rigs and buses off the streets tomorrow.

    I also believe that ozone is being vilified because of it’s medicinal qualities. Look at what BiologyNews.net had to say recently on the subject of medicinal ozone:

    “In fact numerous effective cancer cures have been brought forth over the years, yet they never seem to get to market. This is especially true for ozone therapy, which was started in Germany in 1892, and came to the US in 1898. Since this therapy precedes the formation of the FDA, and happens to be one of the safest therapies on the market, under the law it has a grand fathered approval status. Yet the FDA routinely violates the law by jailing those who perform ozone therapy. Chemically ozone destroys cancer through multiple mechanisms. First of all malignant tumors lack the protective antioxidant enzymes catalase, glutathione peroxides, selenium methionine peroxidase, and superoxide dismutase, which protect healthy cells. When ozone reacts with the lipid membrane of the cells a lipid peroxide is formed. Hydrogen peroxide is also formed by the reaction of ozone with water. These peroxides enter in to all cells. The antioxidant enzymes in the healthy cells break down the peroxides in to water and oxygen. Cancer cells on the other hand cannot break down these peroxides, thus these cells swell up and burst. Secondly the peroxides stimulate white blood cell activity. In fact NK (natural killer) cells use peroxide in the same manner to kill cancer cells. Ozone, being a strong oxidizer, kills cancer microbes, and carcinogens, such as xenoestrogens. As far as safety goes, a study done in Germany followed over 6.5 million doses of ozone given for therapy. There were slightly over 30 adverse reactions reported, mostly due to improper administration. Therefore, no therapy can match effectiveness and safety of ozone for cancer treatment.”

    Ozone a toxic gas, smog? Give me a break.

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