On hot days, patients with lung disease such as asthma and COPD often tell Mary Rice, M.D., MPH, that they are having trouble breathing. That led Dr. Rice to wonder whether there is a connection between temperature and changes in lung function. She also wanted to know whether air pollution levels interact with temperature to affect a person's breathing.
With a grant from the American Thoracic Society Foundation, Dr. Rice, a pulmonary and critical care physician at Beth Israel Deaconess Medical Center and an assistant professor of medicine at Harvard Medical School, is studying those questions.
"We know cold temperature can be a trigger for asthma attacks, because it causes airway smooth muscle to constrict," Dr. Rice says. "But the effects of hot temperature are less clear. Some studies suggest hot temperatures also cause airway narrowing. We do know that people with lung disease are hospitalized more frequently when it's hot outside. The reasons for this have not been well explored."
Dr. Rice has been studying data from the long-running Framingham Heart Study. She is looking at participants' lung function, and comparing that with air pollution and temperature data on the days preceding of their lung function testing. She is also using satellite data to estimate the daily temperature right outside participants' homes. "I've already found that when air pollution levels are higher, lung function is worse, but we don't know whether the same increase in particulate matter is more toxic on a hot or a cold day compared to a more moderate temperature day," she says.
The analysis is beginning with all Framingham Heart Study participants, most of whom are free of lung disease, but she also plans to look specifically at those with chronic lung disease to see if they are more susceptible to changes in temperature.
Dr. Rice explains that currently, the Environmental Protection Agency's color-coded Air Quality Index does not take temperature into account. "If multiple studies find ozone or particulate matter is more toxic when the temperature it hot—say 90 degrees—then we might modify the warning system," she says. For instance, if the temperature rises above a certain level, a day that is considered to be a good air quality day (green) might be considered a moderate air quality day (yellow), posing a health risk for susceptible people with lung disease like asthma or COPD.
"Heat waves are becoming more frequent with climate change. If we find that temperature affects the toxicity of outdoor air pollution, this could have important implications for people with lung disease," she said.
Page last updated: March 2, 2020