Walk through Donora anytime today and you’ll have to work hard to imagine what the deadly 1948 smog might have been like. You have to divorce the sparkling clean air in Donora today from your mind, block it out completely, to even begin to imagine the worst days of the smog that October.

In that way Donorans are fortunate, more so than residents in a host of cities around the nation and the world. In 2017, for instance, nearly 3,000 people in five areas of California died of pollution-related illnesses. In Pittsburgh, there were 232 deaths, and in Chicago, 120. Nationwide, there were 7,140 more deaths from air pollution in 2017 than in 2010.

Europe has its own hotspots, starting with Italy’s Po Valley. The Po River runs from the western Alps nearly straight across Italy’s northernmost section to the northern Adriatic Sea. Throughout the valley lies a huge swath of polluted air (below), stuck there by the Alps to the north. The pollution stems from home heating fuel and vehicle emissions more than industrial sources.

Southern Poland also suffers from extreme air pollution, largely from coal-fired power plants and the burning of wood, a remarkably common way for residents to heat their homes.

Pollution in Bosnia Herzegovina, Macedonia, and Turkey all have markedly high levels of particulate matter in their air. Perhaps the worst pollution, though, is in South Asia, which houses 18 of the world’s 20 most polluted cities, including cities in India, Pakistan, and Bangladesh.

According to a March 12, 2019 study published in the European Heart Journal, air pollution can take as much as two years of life from anyone exposed to it. “To put this into perspective,” says Thomas Münzel, German cardiologist and one of the study’s authors, “this means that air pollution causes more extra deaths a year than tobacco smoking, Smoking is avoidable, but air pollution is not.”

As much as the world learned from Donora in ’48 and London in ’52, there remains much work to be done. Let’s hope we do it soon.