Most Americans are now breathing cleaner air, however, some are still living in cities that are more polluted than they were a decade ago, a new report reveals.

The finding came from the American Lung Association's annual report "State of the Air" that examines air quality across the U.S by measuring levels of ozone and small particles in the air in over 1,000 cities from the years 2009 to 2011. The report finds that air quality is following the long-term trend toward significantly healthier air.

Experts used the most recent pollution data - collected by the Environmental Protection Agency - to analyze the two most common types of pollution: ozone (smog) and particle pollution (soot). Then they ranked cities and gave counties grades based on their scores for year-round particle pollution, short-term particle pollution, and ozone.

The most noteworthy progress was seen in declined levels of year-round particle pollution in virtually the whole country. On the other hand, many cities that still ranked among the most polluted, had a greater number of unhealthy days of high ozone and short-term particle pollution from 2012.

Even among the cities that improved, several were still found at the top of the most-polluted category. This included Los Angeles, which had the highest level of ozone pollution, and Bakersfield, California, which had the highest level of particle pollution.

Overall, there were 254 counties with poor levels of particle pollution or ozone; 42 percent of the American population live in these areas. Besides the two cities in California, the following were among those with the highest levels of ozone:
  • Washington D.C.
  • Dallas
  • Houston
  • New York City
  • Cincinnati
  • Oklahoma City
Four cities ended up on all three of the cleanest cities lists - the highest number recorded that made all three lists. Additionally, one city has reduced its unhealthy ozone days by one-third since the first report came out in 2000. Eighteen cities had reduced year-round levels of particle pollution - and 16 cities documented their lowest levels ever.

Air Pollution Has Negative Effects

Air pollution is a dangerous threat to health, especially....:
  • anyone with lung disease, COPD, or asthma
  • individuals with heart disease or diabetes
  • people with low incomes
  • anyone who works or exercises outdoors
  • infants, teenagers, children, and senior citizens
Harmful levels of particle pollution or ozone can result in wheezing and coughing, heart attacks, asthma attacks, and premature death.

A separate study reported earlier this month that fetal exposure to air pollution can increase the risk of pediatric cancers.

Another study published in Environmental Health Perspectives in February of this year revealed that pregnant women exposed to air pollution are at a higher risk to give birth to babies with low birth weight.

Written by Kelly Fitzgerald