<P> Air pollution is the introduction of chemicals , particulate matter , or biological materials that cause harm or discomfort to humans or other living organisms , or damages the natural environment into the atmosphere . Ever since the beginning of the Industrial Revolution in the United States , America has had much trouble with environmental issues , air pollution in particular . According to a 2009 report , around `` 60 percent of Americans live in areas where air pollution has reached unhealthy levels that can make people sick '' . Pollution in the United States has plummeted in the recent decade , with pollutants such as nitrogen dioxide decreasing despite the fact the number of vehicles on the road is n't . This is due to better regulations , economic shifts , and technological innovations . With respect to nitrogen dioxide , NASA reported a 32 % decrease in New York City and a 42 % decrease in Atlanta between the periods of 2005 - 2007 and 2009 - 2011 . Air pollution can cause a variety of health problems including , but not limited to infections , behavioral changes , cancer , organ failure , and even premature death . These health effects are not equally distributed in terms of race , ethnicity , socioeconomic status , education , and more in the United States . California has the worst air quality of any state , and in most surveys the cities in California rank in the top 5 or top 10 of most polluted air in the United States . </P>
<P> Air pollution is the introduction of chemicals , particulate matter , or biological materials that cause harm or discomfort to humans or other living organisms , or damages the natural environment into the atmosphere . Ever since the beginning of the Industrial Revolution in the United States , America has had much trouble with environmental issues , air pollution in particular . According to a 2009 report , around `` 60 percent of Americans live in areas where air pollution has reached unhealthy levels that can make people sick '' . Pollution in the United States has plummeted in the recent decade , with pollutants such as nitrogen dioxide decreasing despite the fact the number of vehicles on the road is n't . This is due to better regulations , economic shifts , and technological innovations . With respect to nitrogen dioxide , NASA reported a 32 % decrease in New York City and a 42 % decrease in Atlanta between the periods of 2005 - 2007 and 2009 - 2011 . Air pollution can cause a variety of health problems including , but not limited to infections , behavioral changes , cancer , organ failure , and even premature death . These health effects are not equally distributed in terms of race , ethnicity , socioeconomic status , education , and more in the United States . California has the worst air quality of any state , and in most surveys the cities in California rank in the top 5 or top 10 of most polluted air in the United States . </P>
where does most air pollution in cities come from
where does most air pollution in cities come from
chemicals
chemicals