One Nation Claims Dozens of World's Most-Polluted Cities

If your city's air pollution has you reaching for the N95, you're not alone. Per a new report from Swiss tech company IQAir, out of 134 nations and regions surveyed, only 10 of them meet an international air-quality standard set forth by the World Health Organization, reports CNN. That standard focuses on PM2.5, "a type of microscopic speck of soot less than the width of a human hair," per the Guardian. When inhaled, these particles that are spewed by vehicles and factories around the globe can various health issues and even death.

• What's safe: According to the WHO, average yearly PM2.5 levels shouldn't go over 5 micrograms per cubic liter.
• Origins and consequences: The burning of fossil fuels, wildfires, and dust storms are a few of the main offenders of PM2.5, which has been tied to respiratory problems in humans, as well as heart and lung disease, cancer, and cognitive issues in kids.
• Places that make the cut: The lucky 10 include Australia, Bermuda, Estonia, Finland, French Polynesia, Grenada, Iceland, Mauritius, Puerto Rico, and New Zealand. The New York Times notes that many of these winners are islands. The United States ranks the 102nd worst, with its PM2.5 levels exceeding the WHO's by one to two times.
• Most polluted nation: That would be Bangladesh, which claims PM2.5 levels that are almost 16 times higher than WHO's standard, per the report. Pakistan, India, Tajikistan, and Burkina Faso are the next most-polluted countries on the list.
• Cities: Of the 100 worst, all but one (Benoni, South Africa) are in Asia. Of those, 83 are in one country: India.
• The toll: About 1 million premature deaths are caused annually by short-term PM2.5 exposure, per the Times. The Guardian notes that 7 million die each year from air pollution overall, which is more than the number who succumb to malaria and AIDS combined.
• Possible remedies: Glory Dolphin Hammes, CEO of IQAir's North America division, says making cities more walkable (resulting in fewer cars and trucks), improving forestry practices to keep wildfires at bay, and turning to clean energy can all help.

(More air quality stories.)