Ozone can aggravate asthma, causing more asthma attacks, increased use of medication, more medical treatment and more visits to hospital emergency clinics. Results of animal studies indicate that repeated exposure to high levels of ozone for several months or more can produce permanent structural damage in the lungs. Among those most at risk to ozone are people who are outdoors and moderately exercising during the summer months. This includes construction workers and other outdoor workers. Exercise and outdoor activities can play an important role in maintaining good health.
Physical exertion helps build up strength in the heart and lungs.
But exerting yourself outdoors can actually increase your chances of experiencing health effects when ozone concentrations are at unhealthy levels. When this happens, more ozone is taken into your lungs, and ozone reaches tissues that are susceptible to injury. Research has shown that respiratory effects are observed at lower ozone concentrations if either the level or duration of exertion is increased. This is why EPA recommends decreasing the level or duration of exertion to avoid ozone health effects. Examples of typical daily activities that involve moderate exertion include climbing stairs, light jogging, easy cycling, playing tennis or baseball, and stacking firewood.