If it’s a “green” day we can breathe easy. Thanks to growing concern about the health dangers of inhaling smog and particle pollution, over the past 20 years weather forecasts have given us a daily download on our local air quality. To do that, forecasters tap the Environmental Protection Agency’s Air Quality Index, which rates conditions in 900 counties across America.
The system revolves around a 10-pound device called Elm, which can be installed anywhere and runs on Wi-Fi. Once it’s booted up, Elm provides updates on the amount of particulate matter, nitrous oxide, and other pollutants in 20-second intervals. All that local data is beamed to a real-time, color-coded online map that anyone can access.