I have severe COPD, which is my fault caused by 45 years of smoking. I have been told to quit, which I am working on. I have a really hard time breathing in severe cold/hot weather or if the air is hanging low.
We have a paper factory in my community, and they have done a lot in the last 30 years or so to clean up their air output. When my family first moved here in 1961, the town stunk from the paper mill— now you hardly ever smell it. I still can't go outside on really hot days, because I can't breathe, and I have to stay indoors with the air conditioning.
