Those numbers are startling, and that’s the point. University of Chicago researchers wanted to make air quality measurements less abstract and more relatable — and what is more relatable than years of life?

The pollution most responsible for shortening lives consists of the tiniest airborne particles, called PM2.5. They are small enough to penetrate deep into the lungs and bloodstream, causing breathing and cardiovascular problems, cancer and possibly even dementia. They’re bad for healthy people and terrible for young children, the elderly and anyone who already has heart or respiratory problems.

The particles are light enough to hang in the air for a long time and travel with the wind, which is why wildfires in California triggered air quality alerts and forced school closings many miles away.

The Chicago team started with satellite data that mapped the annual PM2.5 concentration in air all over the world, from 1998 to 2016.

They filtered out the particles that came from dust and sea salt — less than a fifth of the total — so they could focus on the majority, which are generated by vehicle exhaust, combustion of fossil fuels, burning crops and other human activity.

Then they calculated how much longer people would live if the air they breathe had fewer — or none — of these particles. The result of the project is the Air Quality Life Index.

These numbers are a warning, however, not a death sentence.