America is on fire … again. More than a million and a half acres are burning in 15 states, from Arizona to Alaska. More than 3,000 firefighters are working to contain the Mendocino Complex Fire 100 miles north of San Francisco, now the largest in California history, and over the weekend, lightning strikes sparked dozens of new wildfires across the state of Washington. Near Mount Shasta, the deadly Carr Fire has so far incinerated 1,077 homes, forced mass evacuations, and killed eight.

Putting a few hundred miles between you and combustion country certainly confers some measure of safety. But not as much as you might think. While wildfires are geographically limited by nearby fuel sources, wildfire smoke goes wherever the wind takes it. Carried on eastward-flowing air currents, dangerous particulate matter from wildfires is increasingly smothering large swathes of the US, causing health scares wherever these air pollution spikes hit. Welcome to the United States of Smoke.

Animation by NOAA

“Minnesota actually gets just about the most smoke days of any state in the US, you just don’t notice it,” says Nolan Miller, an economist at the University of Illinois at Urbana-Champaign who studies the deadly health impacts of temperature and weather extremes on the elderly. In new research, his group discovered that smoke shocks can also kill. More than 1,000 people die each year from downwind exposure, according to Nolan’s analysis, which is detailed in a working paper. Smoky days also sent more people to emergency departments and doctor’s offices than on days without smoke, especially folks with cardiovascular or respiratory conditions. “The key message of our research is that the bulk of the health burden of wildfires is not felt by people living really near the fire, but rather, on people hundreds or even thousands of miles away from the source,” says Eric Zou, an economist who led the satellite data analysis.

Historically, it’s been difficult for researchers to conclusively connect wildfire smoke with specific health outcomes because of patchy data—fires tend to occur in rural areas that often lack air pollution monitoring coverage and where few people live. But satellites are beginning to change that.

Using smoke plume image data from the National Oceanic and Atmospheric Administration, Miller’s group derived a daily smoke exposure status for every zip code in the US for every day between August 2005 and December 2013. By linking this geographic smoke score to air pollution monitoring data and deidentified billing records for every Medicare beneficiary over the same time period, they were able to construct an eight-year, day-by-day look at how the country’s elderly fared during smoke shocks—sometimes down to a few square miles. Miller says it’s the first national-scale study of wildfire smoke health impacts using satellite data, though he stresses that the results are just preliminary.