Air quality in Butler County was once again affected by Canadian wildfire smoke Monday, July 17, but meteorologists predicted residents will breathe easier throughout the week.

The Pennsylvania Department of Environmental Protection declared a Code Orange Air Quality Action Day on Monday, as high concentrations of fine particulate matter affected the air quality.

Fred McMullen, meteorologist with the National Weather Service in Pittsburgh, said the smoke Pennsylvanians saw in June was from fires in central Canada, but Monday’s smoke originated in the western provinces.

“(Tuesday’s) air quality should be better. Air concentrations won’t be as high,” he said Monday. “The wind is not going to change much in the coming days.”

The sky’s “milky” appearance Monday morning can be attributed to the high air concentration compared to the level of particulates, he said.

“That’s why you can actually see the sun in the sky,” McMullen said.

For most of the state, including Butler County, the Code Orange designation expires at midnight on Tuesday, July 18.

Another alert was issued for July 18 for portions of Eastern Pennsylvania.

Sensitive groups were advised to limit outdoor activity during the Code Orange Air Quality Action Day. Affected groups include young children, the elderly and those suffering from respiratory diseases like bronchitis or asthma.

The DEP encouraged residents to check airnow.com for updates on the air quality.