Wildfire smoke means one more number to track during our daily doom-scrolls. | Al Seib/Los Angeles Times via Getty Images

And even if you don?t live there, you?ll probably be looking at your AQI number someday soon. While the world gaped at the photos when the West Coast skies turned orange, the truth for many residents here is that orange would have been a welcome relief, as opposed to red, purple, or deep maroon. Not the color of the sky, of course, but the color-coded index of toxic airborne pollutants, which, this week, reached maroon level ? hazardous ? for much of the western third of the United States. And inevitably, because there?s an app for that, a huge number of Westerners are glued to their air-quality trackers, structuring their lives around whether their hometown dot is closer to green than to burgundy. Air-quality apps have become a constant ? don?t make me say they?re the summer?s hottest item ? for those living in the states where hundreds of wildfires have created smoky skies and burning eyes for tens of millions of people. As cities in the Pacific Northwest, like Portland and Seattle, recorded some of the worst air quality in the world, all eyes were on apps like AirVisual, AirNow, and PurpleAir, with their readings escalating, in some cases, beyond what some apps could reliably measure.

this one goes to eleven pic.twitter.com/WEF9WZUlzU? Tim Dickinson (@7im) September 14, 2020

Air-quality index, or AQI, is the Environmental Protection Agenc...