An air quality alert is issued when air pollution is high, so we can adjust our activities and avoid certain things, like being outdoors during the hottest part of the day. When heat and sunlight mix with exhaust from vehicles and industry, ozone levels rise. Ozone is one of five pollutants considered when calculating air quality. High ozone can aggravate asthma, leading to coughing, wheezing or chest tightness, and allergy sufferers are impacted by ozone as well.