Strange smell around McKees Rocks area likely caused by temperature changes

Weather is likely to blame for the strong smell affecting places like McKees Rocks and Neville Island, according to health and weather officials.

Residents first began reporting the smell around 4:30 a.m., according to the Allegheny County Health Department. Officials said the county Emergency Management Agency investigated and “the odor appears to be the result of a weather inversion.” Some people could smell it in Downtown Pittsburgh.

By later afternoon, health officials still had not determined the exact source of the odors, but they assured residents they have no evidence the smell would harm anyone.

A weather inversion, also called a temperature inversion or thermal inversion, happens when the surface level of the atmosphere cools to a lower temperature than the air above it in the first 1,000 to 2,000 feet of the atmosphere, according to Michael Brown, a meteorologist with the National Weather Service in Pittsburgh.

Put simply, the air temperature gets warmer the higher it goes. When that happens, Brown said, the cooler, surface-level air isn’t able to rise – it’s trapped.

“Any pollutants or anything in the atmosphere can’t go above that inversion,” Brown said.

That includes any chemical smells that might be given off from industrial areas. Tribune-Review news partner WPXI-TV indicated the odor was initially said to be coming from Neville Island. The TV station reported that production on Neville Island was shut down because of the smell.

Brown said such inversions are relatively common, especially at surface-level.

“They happen very frequently in the morning or overnight as we cool down during the night,” he said.

He noted that the phenomenon on Thursday was, however, one of the stronger ones the area has seen in a while.

“The cold front went through, and it was a very dry, clear morning,” Brown said. “So the temperature near the ground was able to cool.”

Several users of the Smell Pittsburgh app, which crowdsources smell reports around the area to track how pollutants move with the air, ranked the smell as a five out of five – described as “as bad as it gets.”

One user described a “strong chemical odor” that caused burning eyes, a headache and respiratory irritation. Another described an “industrial chemical odor.”

One described the smell as “like burning chemicals.”

“Woke me up from a dead sleep,” they wrote.