Air polution has a myriad of harmful effects. Some are worse than others. The worst effect is that it is breathed right into the body which causes a large array of medical problems. Respiratory ailmets may be the most dramatic and extensive. That includes conditions like asthma and bronchitis as well as more serious ailments like lung cancer.
Some do not even realize that it was air pollution that cause their medical condition which is sad because they at least need to know where to place blame. Air pollution is so rampant, no one can really escape it but some places are worse than others like India and China, for instance.
There are places within the United States which are bad as well like Los Angeles and New York City. And, there are other problems air pollution causes besides just respiratory ones.