You might remember the 1963 hit song by Nat King Cole: “Roll out those lazy, hazy, crazy days of summer, those days of soda and pretzels and beer.”  I remember hearing this song when I was young. I never thought those “hazy … days of summer” would cause me difficulty in breathing. The culprits for the hazy days we experience in Maine are typically ozone and particulates.

Ozone is a highly reactive and unstable gas capable of damaging living cells like those present in the linings of the human lungs. This pollutant forms in the atmosphere through complex reactions between chemicals emitted from vehicles, industrial plants, consumer products and many other sources. The majority of Maine’s ozone comes from upwind sources outside of Maine.

A nationwide scientific study discovered that long-term exposure to high levels of ground-level ozone is linked to significantly higher risk of dying from respiratory diseases. Other studies have shown that exposure to ozone contributes to poor health and difficulty breathing.

Particulate matter also contributes to the hazy days of summer. The U.S. Environmental Protection Agency has designated particulate matter as coarse (10 to 2.5 micrometers), fine (2.5 micrometers or smaller) and ultrafine (0.1 micrometers or smaller). The small size of particles is directly linked to their potential to cause health problems. Very small particles can get deep into your lungs, and some may even get into your bloodstream. Exposure to such particles can affect both your lungs and your heart.

In June Maine issued several particulate warnings due to wildfires in Quebec, Canada. The wind was in such a direction that the smoke and particulates traveled hundreds of miles into Maine. Other sources of particulate materials include camp fires, brush fires, road dust, tobacco smoke and vehicle exhaust.

Numerous scientific studies have linked particle pollution exposure to a variety of problems, including: coughing, difficult breathing, decreased lung function, aggravated asthma, development of chronic bronchitis, irregular heartbeat, nonfatal heart attacks and premature death in people with heart or lung disease.

People with heart or lung disease, children and older adults are the most likely to be affected by particle pollution exposure. Even if you are healthy, however, you may experience temporary symptoms from exposure to elevated levels of particle pollution.

The best protection you can have is to avoid exposure to tobacco smoke, wood smoke, vehicle exhaust and other sources of airborne particles. Avoid prolonged outdoor exertion near high-traffic areas. Stay informed about air pollution alerts and advisories from your local weather forecast, and check Maine’s Air Quality Index alerts at and click on “Maine Air Quality Forecast.”

If you experience respiratory or cardiovascular symptoms (e.g., persistent cough, burning eyes, wheezing, shortness of breath, tightness of chest or chest pain) on AQI alert days, consult a health-care professional, as needed.

Doug Saball is an environmental specialist with the Maine Department of Environmental Protection’s Bureau of Air Quality. In Our Back Yard is a regular column of the DEP. E-mail environmental questions to or send them to In Our Back Yard, Maine DEP, 17 State House Station, Augusta, ME 04333.