New York City, Long Island and the Hudson Valley will all experience air quality within the 101-150 range on the air quality index Sunday, the state’s Department of Environmental Conservation forecasted—meaning the air could contain fine particles and could be “unhealthy for sensitive groups.”

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

The air quality index (AQI) is predicted to be above 100 in much of New York state on Saturday, and could reach 135. Alerts are also in place for parts of New England. The AQI measures the severity of pollution in the air and categorises health risks. The higher the number, the more unsafe the air is to breathe.