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Vermont’s air quality is often considered to be among the best in the nation. However, the air we breathe is not pollutant-free. Motor vehicles, building heating systems and manufacturing all generate air pollution. Our air quality is also affected by emissions that occur outside of the state, from sources such as electricity generating facilities and wildfires. The weather also plays an important role. Brisk winds and fast-moving weather fronts move pollutants out of our area, while stagnant weather systems can cause pollutants to linger and accumulate, particularly in mountain valley areas.
As the seasons change, so do the sources and causes of decreased air quality. Hazy hot summer days combined with increased motor vehicle emissions during “driving season” can result in increased concentrations of ground level ozone and volatile organic compounds contained in fossil fuel. As winter and “heating season” arrives, emissions from furnaces and boilers, in particular those using wood for fuel, increase and can be trapped in valley areas during temperature inversion events. Throughout the year, fuel burning, agriculture and industry release heat-trapping greenhouse gases such as carbon dioxide, methane, nitrous oxide and sulfur hexaflouride into the atmosphere.
The federal Clean Air Act identifies six common air pollutants:
- Ground Level Ozone
- Sulfur Dioxide
- Nitrogen Dioxide
- Particulate Matter
- Carbon monoxide
These are known as the criteria air pollutants. The U.S. Environmental Protection Agency sets and periodically revises national ambient air quality standards for these six pollutants.
In addition, there are 290 pollutants classified as air toxics/hazardous air contaminants in state regulations. 75 of these are known or suspected carcinogens.
While air pollution affects all of us, it is particularly harmful to children, seniors, and those already suffering from a respiratory illness.