Are you familiar with the term, mad hatter”? Hatters were actually mad, driven mad by inhaling lead fumes they used to shape and form hats, 19th century.
Do you think the pseudo-scientific politicians knew lead was a poison, when dentists started putting lead in fillings?
When dental practitioners and political practitioners started with lead in fillings, the studies showed lead was not inert, and that it was toxic when bonded with various elements in various dental compounds.
There were no studies that showed lead in fillings was safe. Did they think about doing studies?
So, if you think “they”, the U.S. government, not the Government of The Republic of The United States of America, would not poison you with rat poison (fluoride) in your drinking water, fiberglass in cigarette filters, unnecessary chemicals in soaps and cleaners, mercury in vaccines, thalidomide that produced deformities in newborns, viruses in vaccines, herbicides and pesticides in food (Monsanto, Bayer), then you could not possibly believe your air is being polluted.
You are ruled by a corporation: the United States Government, that wants you controlled, exploitable and plundered, or dead.