According to the US EPA Air Pollution Trends website, the national average ozone levels declined in the 1980's, then plateaued during the 1990's, and decline a little after 2002. The average ozone concentration has decreased 19% since 2000 in the Northeast region of the US, according to the US EPA Air Pollution Trends website. The average ozone concentration has decreased 9% since 2000 in the Western region of the US, according to the US EPA Air Pollution Trends website. Alth

In 1964, New York City had the worst air pollution among big cities in the United States.(1) It had 32 garbage incinerators that were operated by the city, and 17,000 others in apartment houses.(1) Many power plants in the city were fueled with coal and oil, which led to noxious emissions.(1) During the Thanksgiving weekend of 1966 a haze of smog that consisted of sulfur dioxide and carbon monoxide, wrapped around the city. (1) Approximately 200 people died.(1) The fastest-gr