"While it may improve a little bit later on today or tonight, I think the air quality could go back down again beginning Tuesday and perhaps into Wednesday," AccuWeather Senior Meteorologist Tom Kines told The Post.

Officials warned young children and those with respiratory illnesses to take precautions. For weeks, smoke from Canadian wildfires has been drifting across the border.

As wildfire smoke becomes a frequent summer hazard across large parts of the US, knowing the risk at the neighborhood scale matters for human health.