During a casual conversation about the inversion and related breathing problems, someone asked, “Have you checked your furnace filter lately?” I replied that I had just changed it in January.

“Check it again,” he said. “I just changed mine, and it was filthy.”

Well, I did, and just as predicted, it was dirty. Just because a person stays indoors doesn’t mean they aren’t breathing polluted air.

I applaud those who are pursuing a reduction of air pollution.

Harry W. Patrick

Salt Lake City,