The extent of air pollution in the United States is demonstrated by the NASA satellite image that reveals the vast “veil” of smoke that covered humanity New York. Smoke from the devastating wildfires in Canada has reached the US Midwest, Greenland and Iceland, and even Norway.

Tellingly, more than a dozen US states were on air quality alert Wednesday as smoke from hundreds of wildfires in Canada drifted further south. The skies of many cities have taken on a grayish, hazy color, and local officials are urging residents to stay indoors.

Health officials from Vermont to South Carolina on the East Coast, but also in Ohio and Kansas in the US Midwest, called million inhabitants to limit the time they spend outdoors. Microparticles suspended in the atmosphere can cause difficulty breathing and pose health risks, they warned.