Do I have an Ozone Issue?
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1 - How am I exposed to indoor ozone?

Ozone can be transported from outdoors to indoors via various pathways, including mechanical ventilation, natural ventilation, and air infiltration.  Because ozone is highly reactive, it can interact with surfaces, such as ventilation system ductwork or building materials, as it penetrates the indoor environment. Such reactions usually result in lower ozone levels indoors than outdoors.  However, indoor ozone concentrations can approach outdoor levels when windows or doors are open. You may experience high ozone concentrations indoors if you live in an area where the outdoor ozone level is high (often just for some period during the day) or if there is a significant ozone source in the space. Click here for more information.

Ozone can be generated indoors from certain office equipment such as photocopiers and laser printers.  In addition, air cleaners that either purposely generate ozone or emit ozone as a byproduct can be significant ozone sources and consumers should be aware of this hazard.  Some manufacturers or vendors suggest that ozone will render almost every chemical contaminant harmless by producing a chemical reaction whose only by-products are carbon dioxide, oxygen, and water. This is misleading. Available scientific evidence shows that, at concentrations that would be safe for humans, ozone is ineffective in controlling indoor air pollution. Click here for more information.

2 - What are the health effects of ozone?

Ozone can harm the lungs and respiratory system. The health effects of short-term ozone exposure have been extensively studied and are well documented. For example, inhalation of ozone can decrease lung function and cause some or all of the following symptoms:
  • Cough
  • Pain on deep inspiration
  • Shortness of breath
Click here for more information on short-term ozone health effects.

Research on the health effects of recurrent or long-term exposure to ozone currently is underway. The subjects in a small number of studies that have examined the potential effects of long-term workplace exposure to ozone have reported headache, irritation of the nose and throat, chest constriction, and lung congestion. Click here for more information about the health effects of ozone.

More detailed information about the health effects of breathing ozone can be found at the following websites:

American Lung Association, State of the Air: 2009 Health Risks Overview - Ozone
http://www.stateoftheair.org/2011/health-risks/health-risks-ozone.html

U.S. EPA, Ozone and Your Patients' Health
http://www.epa.gov/03healthtraining/

Canadian Centre for Occupational Health and Safety: Ozone
http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/ozone/health_ozo.html

Besides its own adverse health effects, indoor ozone can cause additional health concerns due to its ability to react with VOCs and semi-volatile organic compounds (SVOCs). These reactions may occur in the gas phase or on surfaces, forming products called ozone-derived secondary emissions. Some of these ozone reaction products, such as formaldehyde, acrolein, and ultrafine particles, are known to have adverse health effects. Information on the health implications of ozone-derived compounds currently is being gathered.

3 - How do I know if ozone is affecting my family's health?

The occurrence and severity of health effects from ozone exposure vary widely among individuals.  Five groups of people are especially vulnerable to the effects of breathing ozone:
  • Children and teens
  • Anyone 65 or older
  • People who work or exercise outdoors
  • People with existing lung disease, such as asthma or chronic obstructive pulmonary disease (also known as COPD, which includes emphysema and chronic bronchitis)
  • Responders who are otherwise healthy but for some reason react more strongly to ozone. Click here for more information.
When exposed to ozone, you may experience coughing or have impaired or painful breathing.  Sometimes, damage caused by ozone and its related secondary pollutions can occur without any noticeable signs. Therefore, the best way to protect yourself and your family is to eliminate indoor ozone sources and to take precautions (e.g., close doors and windows) when outdoor ozone levels are high to minimize exposure even when you do not feel obvious symptoms.

4 - What should I do to protect myself from ozone?

First, eliminate indoor ozone sources as soon as you can.  Do NOT use an ozone generating air cleaner in an occupied space. Take precautions and look for a test certification if you are using an air cleaning device which may generate ozone as a byproduct.  Such devices may include electronic air cleaners, ultraviolet (UV) lamps, and devices that claim to use reactive oxidation species/ions or plasma to remove indoor pollutants.   

Also pay attention to the air quality forecast.  See Where can I find outdoor ozone levels in my location?

When possible close doors and windows while the outdoor ozone level is high. High or elevated ozone concentration would be above the California ambient ozone standard of 0.07 parts per million over an eight hour period.    

Note: A part per million (ppm) refers to one part of the substance dissolved into a million parts of another substance.

5 - Can I use ozone-generating air cleaners?

Air purifiers that purposely emit ozone (ozone generators) should NOT be used in homes or offices because they can emit unsafe levels of ozone.  Warnings on these devices have been issued by the U.S. Environmental Protection Agency (EPA), the California Department of Public Health (CDPH), and the American Lung Association (ALA):
Cautions must be taken with air cleaners that may be effective at removing other indoor contaminants (e.g., particles) but which emit ozone as a byproduct (e.g., electrostatic precipitators) to make sure that they do not emit unsafe levels of ozone. The California Air Resources Board (CARB) passed a regulation in 2008 to limit the ozone emitted from indoor air cleaning devices in order to protect public health.  All air cleaning devices sold in California must have met state requirements by October, 2010. More information on this regulation, a list of California certified air cleaners, and tips on how to select a safe and effective air cleaner are available at http://www.arb.ca.gov/research/indoor/ozone.htm.

6 - Where can I find information on outdoor ozone levels?

Ozone is one of the five major air pollutants regulated by the Clean Air Act.  The U.S. EPA calculates the Air Quality Index (AQI) for ozone. The AQI is an index for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The higher the AQI value, the greater the level of air pollution and the greater the health concern are. Click here to lean more about the Air Quality Index (AQI).

You can check http://www.epa.gov/airnow/ for AQI nationwide. Choose the State of California and you will find information for various locations in California. Or you can get such information directly from your local Air Quality Management Districts (AQMDs), such as South Coast Air Quality Management District and Bay Area Air Quality Management District.  The latest ozone summary data and real-time hourly ozone values (Click here) for locations in California can also be found from Air Quality and Meteorological Information System (AQMIS) website maintained by the California Air Resources Board (CARB).

7 - What are effective methods to remove ozone from outdoor air?

The active removal of ozone can be achieved by commercially available sorption technology (e.g., by activated carbon filters, which are often used for indoor volatile organic compound (VOC) removal as well and catalysts such as metal oxides. Click here to read A Pilot Study of Energy Efficient Air Cleaning for Ozone.

However, such ozone removal filters are often only used in office, commercial, or institutional buildings.  The American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) standard on ventilation for acceptable indoor air quality (ASHRAE Std 62.1 - 2010) requires that ozone air-cleaning devices be provided when the most recent three-year average annual fourth-highest daily maximum eight-hour average ozone concentration exceeds 0.107 ppm (209?g/m3)