Photos: Wildfire smoke is blanketing Mexico City

Smoke from a series of wildfires have reached Mexico City, where officials have declared a state of emergency and are urging people to stay indoors. The level of PM 2.5—the measure of particulate matter in the air per cubic meter—reached 158 yesterday (May 14), far above what is considered safe. Reuters noted that one of the most polluted major cities in the world, Delhi, India has an average level of 113.5.

The influx of smoke in the valley where Mexico City sits didn’t immediately lead to cars being pulled off the streets, since the conditions didn’t originate from auto exhaust. As the pollution persisted, officials began limiting driving.

Photos from recent days show the city, which has long battled pollution, engulfed by smoke and ash.