每年, millions of Americans are exposed to levels of pollution that American public health groups and international agencies consider unhealthy. Fossil fuels are the largest source of air pollution that comes from human activities.
In 2020, 237.6 million Americans – more than 70% of the population – were exposed to more than a month of elevated levels of ozone and/or fine particulate pollution. The map below shows the days on which pollution levels were elevated in locations across the country. (To see the counts of days of elevated pollution in your area, download the full “空气中的烦恼” report.)
There is no “safe” level of air pollution
The pollution in America’s air causes hundreds of thousands of premature deaths every year and contributes to health problems ranging from asthma to dementia.
The World Health Organization (WHO) and studies in the Journal of the American Medical Association, 环境健康展望, 新英格兰医学杂志 have all concluded that any level of air pollution causes measurable health impacts.
此外, current EPA standards for allowable levels of air pollution include levels beyond those the WHO and other bodies consider acceptable. The EPA standard for ozone is 70 parts per billion (ppb) over 8 hours, while the WHO’s guidelines recommend 51 ppb. Similarly, the EPA's standard for allowable fine particulates (PM2.5) in the air is more than twice as high as the WHO's 2021 guidelines for protecting public health.
Global warming and air pollution are linked
Burning fossil fuels produces more than just health-threatening ozone and particulates – it also produces greenhouse gases that are warming our climate. Global warming is likely to make air pollution worse in the years to come.
Higher temperatures, which global warming will make more frequent, can increase ozone levels.
Global warming could decrease air circulation, trapping pollution near the ground where it is most unhealthy.
Global warming will continue to increase the frequency and severity of wildfires. Global warming has already caused wildfires in western states to burn more land, burn for longer and burn during more of the year than they did a few decades ago. Wildfire smoke is a major source of particulate pollution.
Global warming will also increase the rate at which the earth and plants naturally emit pollutants.
The map below shows the total number of days of elevated air pollution — when ozone pollution and/or PM2.5 pollution were above the level that the EPA considers “good” — for each urban area and rural county t