Denver has the worst air quality of any major city in the world as wildfires burn.

Denver was not the best place to spend the weekend. On Saturday, the city recorded the worst air quality of any city in the world for several hours as it continues to suffer the effects of the wildfires ravaging the western United States. The ranking released by IQAir, a Swiss air quality technology company, ranked Denver at the top of its ranking of the world’s 94 major cities for several hours on Saturday, with an air quality index that reached 179. Late Sunday morning, Denver had fallen to number two with an index of 171 while Krasnoyarsk, Russia took first place with a whopping 1,087. After Denver, the next US city in the rankings is Salt Lake City, which Sunday occupied sixth place with an index of 127.

Such a high ranking for Denver means people should wear masks outside, close windows, and avoid outdoor exercise. The Colorado Department of Public Health and Environment said visibility in denver was extremely poor and blamed the smoke from the wildfires for the situation. Despite the poor air quality, people still went out on Saturdays and did outdoor activities. “You certainly work a lot more. Much harder to breathe, panting. It sucks to be honest, ”said local NBC affiliate KUSA, a man who rode 40 miles.

In California, firefighters continued to struggle to control the massive Dixie Blaze, which became the largest wildfire in state history. The massive fire again spread overnight to an area of ​​725 square miles and was only 21% contained.