“This is not the day to train for a marathon or to do an outside event for your children,” Adams said at a press conference on Wednesday. He recommended citizens wear a “high-quality mask” like an N-95.

New Yorkers are experiencing an eerie orange glow brought on by a thick blanket of unhealthy smoke that has drifted south from Canadian wildfires. It’s filled the air with dangerously unhealthy levels of fine particulate matter and according to state officials created the worst air conditions in New York state in more than 20 years, since another Canadian wildfire smoke enveloped the state.

Conditions are forecast to temporarily improve later tonight and tomorrow morning, before they deteriorate again, Adams said. The Federal Aviation Administration said inbound flights to LaGuardia Airport were briefly grounded due to low visibility.

“Yesterday, New Yorkers saw and smelled something that has never impacted us on this scale before,” Adams said. “As I was out walking the streets, clearly we knew something was happening that was beyond normal.”