Surviving the heat isn’t the only concern for people in Atlanta during the dog days of summer, the hottest time of the year in the northern hemisphere from early July to mid-August. During this time, ozone levels peak in most industrialized cities, and heavily populated areas tend to be more at risk for pollution, in part, because of increased emissions from cars, trucks and factories.

Cars on the road

Cherry Wongtrakool, MD, specialist in pulmonary medicine, says pollution is generally broken down into ozone and particulate matter, but can also include carbon monoxide, sulfur dioxide, and nitrogen oxides. Particulate matter is complex and includes organic chemicals including acid, metals, dust, smoke and soil. It is often classified by size and particles less than 10 micrometers are included in the air quality index, a common measure of the air pollution level.

In addition to increasing symptoms of asthma and causing respiratory symptoms like cough and shortness of breath, Wongtrakool says pollution has been associated with cardiovascular and respiratory illnesses.

She notes that studies to date suggest long-term exposure may accelerate atherosclerosis, or hardening of the arteries. Larger population studies have also suggested there are associations between air pollution and increased risk for cancer, and air pollution and increased risk of death secondary to cardiopulmonary causes.

Wongtrakool, who is sssistant professor of medicine in the Division of Pulmonary, Allergy and Critical Care, Emory School of  Medicine, says if you live in a big city like Atlanta, you can reduce your exposure to air pollution by limiting your time in the car, remaining indoors during the hottest part of the day – typically afternoon and early evening – and reducing time spent doing outdoor activity, particularly activity requiring heavy exertion. People with underlying lung disease should avoid going out when the air quality index is poor, she advises.