Q When there's an air quality alert issued for pollution, we're basically told to limit outdoor activities and stay indoors. Why? How does staying indoors help? Doesn't indoor air come from the outdoors? Does it somehow get filtered and cleaned up on its way in? What's causing these air alerts?
A Basically, air alerts reflect two pollution sources: ozone and fine particles. How you respond depends on the type of pollution. Mark Sulzbach of the Minnesota Pollution Control Agency explained it this way:
Summer is ozone season. Ozone is created when volatile organic compounds (VOCs) and nitrogen oxides mix in hot, sunny weather. When ozone levels are high, people are advised to go indoors into an air-conditioned environment. Air conditioning and contact with surfaces can scrub out ozone, thereby reducing ozone exposure.
But that's not the case with fine particle pollution. Although particulates can cause alerts at any time of the year, they're common in winter when temperature inversions and stagnant air help trap fine particles. Health officials don't advise people to go inside to reduce their exposure because you are right: Outside air ends up inside. Fine particles are less than 2.5 microns in diameter; no house will keep them out.
So you can't hide from particulate pollution, and you shouldn't run. The harder and more often you breathe, the more particles will enter your lungs, increasing your risk of symptoms. Of course, since exercise is also important for your health, you'll want determine a balance that's right for you.
The particles can trigger respiratory problems such as asthma. People with existing respiratory and heart problems are considered the most susceptible, and young children are also advised to reduce activity in part because their lungs are still developing.
But even healthy adults may experience reduced lung function and breathing discomfort when working and exercising strenuously. When there is an air alert, experts recommend walking instead of running. For team sports, use more substitutions and take more frequent breaks.
We are all causing poor air quality. Transportation and electricity use account for more than half of our air pollution. Poor air quality is caused by burning fossil fuels and wood, and some natural sources. Every time we drive a car, heat our homes or use electricity we increase the amount of air pollution. And those fun back-yard fires don't help, either. In every air alert we ask the public to reduce driving, idling and electricity use and to postpone recreational fires.
