THE DETAILS: The U.S. Environmental Protection Agency’s lower limit for what’s considered safe ozone exposure is 75 parts per billion (ppb). The researchers in this study wanted to find out if concentrations lower than that could trigger respiratory problems, so they had 31 healthy adults engage in moderate exercise while exposed to concentrations of ozone at 60 ppb, 70 ppb, 80 ppb, and 87 ppb. The adults didn’t have any preexisting respiratory problems, such as asthma, but tests showed they were still hindered by ozone levels lower than the EPA’s 75 ppb limit. Sixteen percent of the group had 10 percent reduced lung function at 60 ppb, and 19 percent experienced lower lung function when exposed to 70 ppb.
WHAT IT MEANS: Ozone is formed when pollutants on the ground react with sunlight, and too much of it can lower lung function, lead to chronic respiratory illnesses like bronchitis, and trigger asthma attacks. What this study shows is that even healthy adults can still be affected by ozone, particularly when they’re outside exercising on hot, smoggy, August afternoons. “One of the things that people have to realize is there there’s a lot of variability in how different people respond to ozone,” says lead author Edward Schelegle, PhD, associate professor of physiology in the department of anatomy, physiology and cell biology at the University of California, Davis, School of Veterinary Medicine. And because healthy people might assume that they’re not affected by pollution, they may not know how to tell when they’re being overexposed to ozone, says Schelegle.
Here are some warnings signs everyone should be aware of, especially for when exercising outdoors in hot weather:
• Coughs and pain when you take a deep breath. These are two classic signs of ozone exposure, Schelegle says.
• Inability to take a deep breath. Ozone causes inflammation of lung tissue that prevents your lungs from filling to capacity, which you may notice while you’re exerting yourself. There may not be pain associated with deep breaths, but you’ll notice that you can’t seem to take as deep breaths as you normally would, he says.
• Shortness of breath. “Once you start experiencing shortness of breath, you should back off from what you’re doing,” Schelegle advises. It doesn’t necessarily indicate high ozone, but other pollutants may be hindering your lung function.
• The green “good” sign. Ozone warnings aren’t just for people with breathing problems. Healthy adults should check the EPA’s AirQualityNow.gov website to see if the ozone in their cities is at hazardous, or even lower, unhealthy levels, before exercising outdoors.