Air Quality and Health Information

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Air Quality Index

The AQI is an index for reporting daily air quality, developed by the EPA. It tells citizens how clean or polluted their air is, and what associated health concerns they should be aware of. The AQI focuses on health effects that can happen within a few hours or days after breathing polluted air. The purpose of the AQI is to help citizens understand what local air quality means to their health. To make the AQI as easy to understand as possible, EPA has divided the AQI scale into the different categories shown below.

Air quality is measured by a network of monitors that record the concentrations of the major pollutants at locations throughout the state. These raw measurements are then converted into AQI values using standard formulas developed by EPA. An AQI value is calculated for each of the individual pollutants in an area.

The AQI is based on:

  • ozone levels averaged over an eight-hour period, in parts per billion, and
  • particle pollution levels averaged over a twenty-four hour period, in micrograms per cubic meter.

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Air Quality Index Air Quality Descriptor Health Effects Color Code Averaged Values
Ozone Particle Pollution
0-50 Good No health impacts are expected when air quality is in this range. GREEN 0-54 0-9.0
51-100 Moderate Sensitive people should consider reducing prolonged or heavy exertion. Watch for symptoms such as coughing or shortness of breath. These are signs to take it a little easier. YELLOW 55-70 9.1-35.4
101-150 Unhealthy for Sensitive Groups People with respiratory or heart disease, the elderly, teenagers and children should reduce prolonged or heavy exertion. It is okay to be outside, but take more breaks and do less intense activities. Watch for symptoms such as coughing or shortness of breath. Asthmatics should follow their action plans and keep quick relieve meds handy. Those with heart disease should watch for symptoms such as palpitations, shortness of breath or unusual fatigue and contact your health provider of necessary. ORANGE 71-85 35.5-55.4
151-200 Unhealthy People with heart or lung disease, the elderly, teenagers and children should avoid prolonged or heavy exertion and consider moving activities indoors or rescheduling. Everyone else should reduce prolonged or heavy exertion. Take more breaks during all outdoor activities. RED 86-105 55.5-125.4
201-300 Very Unhealthy People with respiratory or heart disease, the elderly, teenagers and children should avoid any outdoor activity. Move activities indoors or reschedule to a time when air quality is better. Everyone else should avoid prolonged or heavy exertion. Consider moving activities indoors or rescheduling to a time when air quality is better. PURPLE 106-200 125.5-225.4
300+ Hazardous Everyone should avoid all physical activity outdoors. Asthmatics should follow action plan and keep quick relieve meds handy. MAROON 200+ 225.5+

Visit AirNow for more AQI information.

Your Health

Who is most at risk from ozone and particle pollution?

  • Children and Teenagers - Their respiratory systems are still developing and they breathe more per pound of body weight than adults.
  • Individuals with a lung disease - Ozone and particle pollution put additional stress on the lungs in addition to causing various reactions within the lungs. People with existing lung disease have less tolerance for the effects of pollutants.
  • Individuals with heart disease - Particle pollution has long been known to negatively impact heart function but recent studies are also finding a link between ozone and negative impacts on heart function. People with existing heart disease have less tolerance for the effects of pollutants.
  • The Elderly - As people age, their bodies have less tolerance for the effects of pollutants.
  • Individuals who are exerting themselves - At higher levels of pollutants even healthy adults who are exerting themselves will bring in more air and thus more pollution into their lungs.
  • New or expectant mothers may also want to take precautions to protect the health of their babies.

Sensitive individuals who limit their exposure to poor air quality will reduce the likelihood of the need for additional medication, emergency department visits, and hospitalizations. DEP staff meteorologists remind you to 'Keep an eye on the AQI.'

Indoor Air Purifiers

Some indoor air purifiers use ozone to clean the air. However, Ozone in the lower atmosphere is a pollutant. There is no doubt about that. While ozone can clean the air, one needs to monitor its use very closely to avoid unhealthy levels. This is a very complicated process and not easily accomplished without sophisticated monitoring equipment and continuous vigilance.

The Maine Indoor Air Quality Council covers general indoor air quality issues at:

The U.S EPA deals with indoor air in general at:

California Air Resources Board has issued a report assessing the health impacts of indoor air pollution. Air 'purifiers' that emit ozone were included in their list of indoor air pollution sources which contribute to asthma, respiratory disease and more. For more information go to:

Pollen (aeroallergens)

Maine DEP is aware that pollen & molds, aka aeroallergens, impact people's health. The Maine DEP, in collaboration with the Maine CDC, is currently working on the deployment of new sensors capable of continuously measuring the levels of aeroallergens and other particulates in the air. The data from these sensors are not yet publicly available while we develop our understanding of these new sensors and work to improve the quality of the data.

There is currently only one source of aeroallergen data in Maine and it is the Micmac Tribe in Presque Isle. Their data is not available on the web at this time but if you live in northern Maine and would like to find out what the values are you can sign up to be added to their email list. To do so, please contact Dave Macek at

The National Allergen Bureau (NAB) does have a 'network' of monitors ( but the closest one is in Connecticut. This would not be representative of what we in Maine are exposed to. Unfortunately, many of the NAB's monitors are funded by local allergists who view the data as proprietary for their patients only.

The Council of State and Territorial Epidemiologists (CSTE), in collaboration with the National Atmospheric Deposition Program's (NADP) Aeroallergen Monitoring Science Committee (AMSC), is working to establish a coordinated, standardized, quality assured, national aeroallergen network, whose data is publicly available.

Smart Exercise

Maine forecasts are issued using an Air Quality Index (AQI). The AQI color codes identify pollution levels and include specific health messages for each category. If you are concerned about your health a good motto is to "Keep an eye on the AQI."

Although Maine 's bad air days are infrequent, there are still some days when air quality can be a problem for sensitive people. During these days you'll hear warnings to avoid strenuous or prolonged activity outdoors. This does NOT mean that you shouldn't exercise at all, but rather exercise smart.

Smart exercise includes changing the time of day, location and/or the level of your activity, so you won't be exposed to high levels of pollution.

Change the time of the day:

  • Ozone is a photochemical pollutant, which means it needs strong sunlight to form from other pollutants in the air. Ozone can be a problem during the summer months in Maine and peaks during the afternoon and early evening hours. So you could reduce your exposure to high ozone by exercising in the morning.
  • Particle pollution, however, can be high at any time of the day; although it is usually higher in the morning. So avoid exercising during high particle pollution levels by postponing exercise until the afternoon. Particle pollution tends to be higher in the summer and winter, but lower in the spring and fall.

Change your location:

You can protect your health even more by finding a healthier route for your walk or jog - one which avoids busy roads.

Change your activity level:

In addition to changing the time or location of your workout, you could also change the level or duration of activity by walking instead of jogging or reducing the distance of your run on days when air quality is poor.

Remember, to protect your health exercise smart!

Wildfire Smoke

Wildfire smoke can be a problem in Maine from fires in the state, nearby states, Eastern provinces in Canada and even from fires out west.

Smoke from fires contains many different pollutants including carbon monoxide and particle pollution. Particle pollution effects both the lungs and the heart. Therefore, people with respiratory and/or heart disease should take precautions to protect their health.

In slightly to mildly smoky areas individuals suffering from a respiratory disease, children, the elderly and those with heart disease should:

  • Stay indoors with windows and doors closed,
  • Avoid strenuous activity, such as jogging,
  • Avoid using aerosol products such as cleaners, paints and other lung irritants,
  • Use medications as prescribed, and
  • Give yourself a break! Take it easy!

In very smoky areas everyone should follow the precautions listed above to limit their exposure to particle pollution.

When MEDEP Meteorologists are informed of a fire that may be impacting areas within the state, a special statement and/or a forecast update will be issued on the Air Quality Forecast web page ASAP. Depending on the situation, a press release may also be issued.

For fires located within the state the Maine Forest Service, the Maine Emergency Management Agency, the National Weather Service and local emergency personnel will also be involved and working together to protect lives and property.

If you are directed to evacuate please do so and remember to pack all your medications - you don't know how long it will be before you can return. Also, remember to ask for the safest and least smoky escape route they can recommend.

For more information about wildfire health issues and a map of smoke events check out the links below: