MON VALLEY (KDKA) — People in the Mon Valley are breathing easier, quite literally.

Air quality numbers in the area are getting better, but only after the Clairton area had some of the worst conditions in the country over the last couple of days.

The DEP issued a Code Orange Air Quality Action Day on Dec. 24 and Dec. 25 for the Liberty-Clairton area.

Matthew Mehalik, the executive director of the Breathe Project, said even though the weather has an impact on the amount of pollution emitted by the Clairton Coke Works plant, the weather isn’t what is actually causing the pollution.

WATCH: KDKA’s Amy Wadas Reports From The Studio On The Air Quality.

He says it’s the emissions from the coke plant that accumulate and don’t get blown away.

They stick around and cause health problems for people.

“We suspect that if the weather changes, when there’s more wind, it helps to blow pollution away. But the weather shouldn’t really be a control strategy for protecting our health in Allegheny County. We really need leadership to step up and say this is not acceptable,” Mehalik said.

A fire at the Clairton Coke Works plant one year ago caused high pollution levels.

Myron Arnowitt, the director for Clean Water Action, says there’s been up and down levels in air quality since then.

U.S. Steel issued a statement, saying:

“The elevated levels detected at the Liberty Monitor appear to be due to atmospheric inversion. As ACHD has stated in past alerts, it is impossible to determine the sole source of emissions during strong inversions. Our Clairton Plant is operating normally, with no issues to report. Clairton has been operating at a reduced production rate of approximately 9,000 tons per day due to market conditions. Clairton is on pace to set a record for fewest stack exceedances in December.”

Allegheny County Health Department Deputy Director of Environmental Health Jim Kelly issued a statement, saying:

“The Allegheny County Health Department continues to monitor the air quality in our region following several days of heavy fog, very light winds and continued strong and lengthy temperature inversions. The weather resulted in the DEP twice forecasting a Code Orange Air Quality Action Day for PM2.5 on December 24 and 25 for the Liberty-Clairton area.

“Preliminary data has shown exceedances of the 24-hour federal PM2.5 standard at the Liberty monitor (greater than 35 micrograms per cubic meter) from Saturday, December 21 through Wednesday, December 25. As a result, ACHD’s Air Quality Division has been in daily communication with U.S. Steel and other facilities in the Mon Valley to monitor all activity and ensure compliance with their permits.

“While air quality is expected to continue to improve in the upcoming days, residents are encouraged to submit air quality complaints by calling 412-687-ACHD (412-687-2243).”