I’ve to admit, I’m one of those people who checks the weather compulsively on my smartphone. In the morning, at lunchtime, after dinner, even in bed at night. (I’m in my pajamas with my mouth guard in — what am I going to do, jump out of bed for a midnight jog or something?) But there is something else you should check when you check the daily weather forecast, and that’s the air quality index (AQI).


The AQI is an index for reporting daily air quality. It’ll tell you how clean or polluted your air is, and what health risks might be associated with the current air quality. It is designated by the Environmental Protection Agency and is a gauge of five major pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution, carbon monoxide, sulfur dioxide and nitrogen dioxide. The Clean Air Act was signed by President Richard Nixon in 1970 and essentially focuses on improving human health and the environment around us. By 1990, the Clean Air Act had prevented an estimated 200,000 premature deaths, and the EPA estimates that the act will prevent more than 230,000 premature deaths in the year 2020.


So how does it work? The AQI is essentially a yardstick from 0 to 500. Levels under 100 are generally satisfactory. Levels from 101 to 150 are called “unhealthy for sensitive groups,” meaning that if someone is particularly sensitive, such as a very old or very young person, or someone with heart and lung problems, should limit time outdoors. Levels from 151 to 200 are considered unhealthy for everyone, levels from 201 to 300 would trigger a health alert for serious adverse health effects, and levels from 301 to 500 mean that the air outside is extremely hazardous to everyone’s health.


The air quality tends to worsen on hot days, but the heat outside is not necessarily a measure of air quality, so it’s important to check your area’s AQI in addition to the weather.


So how do you reduce your risk (or your children’s risk) when the AQI is at unhealthy levels? The best thing you can do is limit your time outdoors when you plan to exert yourself physically for hours at a time. For example, if you are planning on spending the afternoon doing yard work, you have the perfect excuse to stay indoors and watch a movie instead. Or, if you are planning on spending three hours at the playground with your kids, a scavenger hunt at the mall may be in order. Even if you’re planning on being outside for only a short time, it's better to choose activities that don’t require heavy exertion. Also, as I mentioned above, those who are particularly sensitive (the young, the elderly, and those with respiratory or cardiac health issues) should take extra precaution.


If you’ve got time, check out this list of the best (and worst) cities for outdoor air quality in the U.S. And you can also download this app to your smartphone so you can always check your location’s AQI, even if you’re not at a computer. Lucky me — now I’ve got something else to check as compulsively as I check the weather.


— Chanie


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What is the air quality index?
The AQI is an index for reporting daily air quality. It’ll tell you how clean or polluted your air is, and what health risks might be associated with the curr