Thursday, April 10, 2008

Ozone online

From Stef 06 at the DEP:

This one's more for Mainer's, but everyone could learn something, enjoy!

Ozone: A New Twist on an Old Foe, In Our Back Yard
It is getting to be that time of year again when ozone levels around the state begin to climb and people that are sensitive to pollution should pay attention to the air quality forecast. That is old news to some of you but there is a new twist this year. The U.S. Environmental Protection Agency (EPA) has revised the ozone National Ambient Air Quality Standard from an 8-hr average of 84 parts per billion (ppb) to 75 ppb! While this level is not as low as many scientists believe it should be, it is certainly a big step in the right direction.
In the upper atmosphere ozone protects us from the sun's harmful UV rays. However, at ground level it is a pollutant which hurts human life by harming the heart and lungs. Ozone is a photochemical pollutant which means that it is not emitted directly, but is created from various other pollutants from power plants and cars in the presence of strong sunlight. That is why ozone levels in Maine are highest on long sunny summer days and lowest during short winter days.
Recent studies have demonstrated that ozone effects people's health at lower levels than previously thought. So it is a good thing that EPA lowered the ozone standard! This means that federal regulations will be in effect to reduce ozone levels across the nation.
In the meantime, what does the new ozone standard mean for Mainers this summer? Maine Department of Environmental Protection (DEP) forecasts air quality every day of the year using the Air Quality Index (AQI). The AQI categories are: 'Good' (green); 'Moderate' (yellow); 'Unhealthy for Sensitive Groups' (orange); 'Unhealthy' (red) and 'Very Unhealthy' (purple). Each category above 'Good' now starts at a lower level than it did before. This means that if ozone levels are typical this summer, we'll have fewer 'Good' days, more days in the 'Moderate' and 'Unhealthy for Sensitive Groups' categories and even a day or two in the 'Unhealthy' category. The length of the ozone season may change as well, ranging from March through October rather than April through September.
If we have a typical summer for ozone, you will likely notice Maine DEP encouraging you to take precautions to protect your health more often than in the past. This does NOT mean that air quality is getting worse, just that the AQI is lower to protect your health.
To find out what the air quality forecast is you can dial the toll-free hotline at (800) 223-1196 or go to and click on the 'Maine Air Quality Forecast'. This website displays Today and Tomorrow's forecasts and has links to current and past data, ozone and particle pollution trends and a wealth of information. You can even sign up for EnviroFlash which is a service that sends you an email when air quality is forecast to be poor in your area. So remember, to protect your family's health 'Keep an eye on the AQI.'
This column was submitted by Martha Webster, Air Quality Meteorologist for the Maine Department of Environmental Protection's Bureau of Air Quality. In Our Back Yard is a weekly column of the DEP. E-mail your environmental questions to or send them to In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333.

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