WASHINGTON, DC - Reading this in the States? Then the odds are that the air you're breathing is dirty enough to kill.
According to the tenth annual American Lung Association State of the Air report, six out of ten Americans - over 186 million people - live in areas where pollution levels actually endanger lives. The number is more than double that identified in last year's report.
Almost all major cities in the US experience unhealthy levels of air pollution, with sufferers from asthma and heart disease particularly at risk. Those on low incomes tend to be subjected to higher levels of pollutants than their richer neighbours.
Many cities are actually worse than before. Dallas and Las Vegas have higher ozone levels than ten years ago, while particle pollution increased in a dozen cities, including Bakersfield, California, Los Angeles and Houston.
The cleanest place is Fargo, ND, which ranked among the best in all three air pollution categories - ozone, short-term particles and year-round particles.
Los Angeles was worst for ozone, although the organisation acknowledges thast it has made huge steps forwards in the last few years. Pittsburgh was worst-affected by short-term particle pollution, and Bakersfield, suffered most from year-round particle pollution.