Masks made a comeback for many residents Wednesday as smoky skies prevailed over the Hudson Valley and health experts advised everyone to stay indoors.

Paul Walsh, CEO, N.A. of Meteomatics and the former chief of weather operations for the U.S. Army, says the air is dangerous because of the particulate matter in the smoke coming from wildfires in Canada.

"The reason that it is so dangerous is because the particulate matter is so small that as we breathe it, it goes into our bloodstream and has a direct impact on things like asthma, COPD…it has an impact on people that have bad heart conditions," he says.

The Westchester County Health Department advised residents to limit strenuous outdoor activity. Commissioner Sherlita Amler says infants and people with asthma, heart disease and other respiratory conditions should limit time outdoors.

Westchester County Executive George Latimer canceled all county-sponsored outdoors events and is advising other organizations do the same. Latimer also recommended that all county employees who work outdoors wear masks as an added safety measure.

Rockland County Fire and Emergency Services Director Chris Kear said his department has received dozens of calls about odors of smoke or reports of outside smoke.  

“Rockland County, and our entire region will be experiencing another day of poor air quality. Conditions will ease up leading into Thursday. It is recommended that if you have asthma, are sensitive to pollutants or experience shortness of breath, you should try and avoid any outside activities. Exposure and also cause irritation to eyes, nose, and throat. Shortness of breath, sneezing, coughing, and runny nose is common. In addition, please keep your windows closed at home or while traveling in your vehicle," Kear said in a statement.

Westchester County was above 150 on the air quality index for Wednesday. Good air quality would be below 50.

The unhealthy air level is because of fine particulate matter, which consists of tiny solid particles or liquid droplets in the air. That comes from situations such as fires.

Gov. Kathy Hochul recommended school districts cancel outdoor activities and is in close contact with impacted cities. Numerous Hudson Valley schools moved recess and physical education indoors.

Sports are being affected too, as the high school boys state lacrosse semifinals in Albany were postponed until Thursday. That affects teams from Rye, Scarsdale, and Pleasantville.