Trouble in the Air

Air pollution and climate change are “two sides of the same coin,” according to the United Nations Environment Program. Climate change will make air pollution worse, while some air pollutants can exacerbate global climate change. 

This is the topic of a recent scientific report written by Elizabeth Ridlington and Gideon Weissman (Frontier Group) and Morgan Folger (Environment America Research & Policy Center).

It is quite a long piece (71 pages with hundreds of references) which you can download as a pdf here:

Here are some highlights from this report.

Particulate pollution can harm human health and also add to global warming. Here, dust and black carbon have coated snow and ice, causing them to absorb more heat from the sun.

Air pollution such as black carbon, a form of particulate pollution, exacerbates global warming. Black carbon in the air readily absorbs sunlight, increasing the temperature of the atmosphere.13 When black carbon lands on snow or ice, it absorbs heat and hastens melting. This can lead to greater warming, as open water and bare ground retain more heat from the sun than do snow or ice. Production of natural gas is a major source of VOCs (Volatile Organic Compounds), which contribute to air pollution via ozone formation (see below), and also releases methane, a powerful global warming pollutant that traps more than 80 times as much heat as carbon dioxide over 20 years.14 Just as air pollution and global warming share some common causes, and are linked together in a self-reinforcing cycle, so too do they share another characteristic: scientific alarm about their threats to the environment and public health.

People across America regularly breath polluted air that increases their risk of premature death, and can also trigger asthma attacks and other adverse health impacts.

In 2018, 108 million Americans lived in areas that experienced more than 100 days of degraded air quality. That is equal to more than three months of the year in which ground-level ozone (the main ingredient in smog) and/or particulate pollution (PM2.5) were above the safe levels as determined by the EPA.

For instance, here on Long Island air quality levels by these measures are: 71-100 days/year above the EPA safe levels for ground level ozone and PM2.5.

Air pollution is linked to health problems including respiratory illness, heart attack, stroke, cancer and mental health problems. Research continues to reveal new health impacts. For example, maternal exposure to air pollution such as fine particulates (PM2.5) and ozone is associated with a higher risk of low birth weight, pre-term birth and stillbirth. For older adults, long-term exposure to particulate pollution has been associated with an increased risk of Alzheimer’s disease and other forms of dementia.

 Air pollution’s effects are pronounced among vulnerable populations, including children, pregnant women and the elderly. Research has found that children exposed to particulate pollution can suffer from lung development problems and long-term harm to lung function.

Each year, millions of Americans suffer from adverse health impacts linked to air pollution, and tens of thousands have their lives cut short.

Two pollutants of special concern are particulate matter and ozone. Fine particulate pollution smaller than 2.5 micrometers (PM2.5) poses especially high health risks because it can be deposited deep in the lungs.18 Ozone that forms near the ground is the main ingredient in smog and is associated with adverse health impacts (as opposed to ozone in the high atmosphere, which blocks harmful solar ultraviolet rays from reaching the earth).  These are the main culprits and are most frequently monitored by the numbers of days at a given location where levels are above the EPA’s “safe level”.

Premature death. Globally, ozone and fine particulate matter are estimated to cause 470,000 and 2.1 million deaths each year, respectively, by damaging the lungs and respiratory system.19 A study published in the Proceedings of the National Academy of Sciences estimated that in the U.S. fine particulate matter generated by human activities was responsible for more than 107,000 premature deaths in 2011.20

A 2019 study published in the New England Journal of Medicine found that when the concentration of fine particulate matter (PM2.5) increased by 10 micrograms (μg) per cubic meter, daily mortality in the U.S. increased by 1.58 percent. A 1.58 percent increase in daily mortality equals an additional 122 deaths in the U.S. on a day when fine particulate pollution increased by 10 μg per cubic meter.21 When coarse particulate matter (PM10) increased by 10 micrograms (μg) per cubic meter, daily mortality rose 0.79 percent.22

The reverse was also observed. A 2009 study compared U.S. metropolitan areas across decades and found that a 10 μg per cubic meter decrease in fine particulate matter concentrations was associated with an increase in average life expectancy of approximately 0.6 years.23

Damage to respiratory and cardiovascular systems. In weeks with elevated ozone or particulate matter pollution, hospital emergency rooms see more patients for breathing problems.24 A 2019 study published in JAMA (the Journal of the American Medical Association) found that higher levels of pollutants including ozone and particulate matter in the air are associated with increased risk of emphysema.25 Air pollution, especially traffic related air pollution, not only worsens asthma but may also cause more people to develop asthma.26 Research also shows strong associations between air pollution and cardiovascular diseases including stroke.27 Particulate pollution is associated with increased risk of hospitalization for heart disease.28

Worsened mental health and functioning. A 2019 study published in PLOS Biology found that poor air quality, including higher levels of particulate matter and ozone, was associated with increases in bipolar disorder.29 Long-term exposure to particulate pollution has also been associated with increased risk of Alzheimer’s disease and other forms of dementia.30

Decreased fertility and harm to pregnancies. Exposure to air pollution has been associated with difficulty in having children, and increased risk of low birth weight and premature deliveries.31 A 2019 study of women in Italy found that higher levels of particulate matter (both PM2.5 and PM10) and nitrogen dioxide are associated with lower levels of ovarian reserve, a marker of female fertility.32 A 2013 study found “short-term decreases in a couple’s ability to conceive” associated with higher levels of PM2.5 and nitrogen dioxide.33 Maternal exposure to PM2.5 or ozone is associated with a higher risk of low birth weight, pre-term birth and stillbirth.34 One study estimated that in 2010, up to 42,800 preterm births in the U.S. and Canada were related to women’s exposure to PM2.5, accounting for up to 10 percent of preterm births.35

Increased cancer risk. Exposure to air pollution can cause lung cancer and other cancers.36 The International Agency for Research on Cancer (IARC), part of the World Health Organization, has found that outdoor air pollution generally, and particulate matter specifically, are carcinogenic to humans.37 The IARC determined that “exposures to outdoor air pollution or particulate matter in polluted outdoor air are associated with increases in genetic damage that have been shown to be predictive of cancer in humans.” In 2010, 223,000 lung cancer deaths globally were attributed to exposure to PM2.5.38

Air pollution likely poses health threats even at levels the EPA considers safe.

Research suggests that “moderate” air quality can, in fact, pose broad threats to public health, and a variety of medical and public health organizations have recommended tighter air quality standards that are more protective of public health. The World Health Organization (WHO), for example, recommends lower ozone and particulate pollution standards than are currently in place in the United States. The American Thoracic Society, the American Lung Association and other health associations support the same standards for fine particulates as the WHO.50

Ozone, the main component of smog, is formed by chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight.56 Fossil fuels – both their combustion and production – are major sources of NOx and VOC emissions.

Particulate matter consists of solid or liquid particles that can be emitted directly from a source or that can form in the air from chemicals such as VOCs, sulfur dioxide, ammonia and NOx.65 Fine particulates smaller than 2.5 micrometers (PM2.5) pose elevated health risks as they can be absorbed deep into the lungs.66 The impact of PM2.5 is further increased by the fact that it is so lightweight that it remains in the air for a long time and can travel hundreds of miles from its source.67 Primary particulate matter is created by a variety of sources, including fossil fuel combustion; dust from roads, agriculture and construction; wildfires; and wood burned for heating.68 On average across the U.S., the majority of the particulate pollution in the atmosphere is secondary particulate pollution, which forms through a chemical reaction.69 Secondary PM2.5 can be created from sources including sulfur dioxide emitted by burning coal and other fossil fuels for electricity generation and industrial power; nitrogen oxides from fossil fuel combustion; and ammonia from fertilizer and manure.70 Mobile sources (including cars, trucks and other on-road vehicles and also off-road vehicles) accounted for 20 percent of both primary and secondary PM2.5, according to one 2004 study.71

Global warming will make air pollution worse. 

Higher temperatures have already resulted in increased ozone, despite lower emissions of the chemicals that create ozone. In the central U.S. in the summer of 2012, for example, higher temperatures caused higher levels of ozone than in the years before and after.83

The American Lung Association found that ozone was higher in the 2014 to 2016 period than in previous recent three-year study periods, and attributed the increase to higher temperatures.84

Hotter, drier conditions have increased wildfires, which create particulate pollution as well as VOCs and nitrogen oxides that contribute to ozone formation. By one estimate, global warming nearly doubled the total acreage that burned in western states from 1984 to 2015, compared to a scenario in which the climate had not changed.85 Wildfires also burn for longer, causing more prolonged and widespread exposure to pollutants. The typical large wildfire now burns for more than seven weeks, compared to less than a week in the 1970s.86

One study estimates global warming will increase the number of air pollution-related premature deaths if no measures are implemented to counteract global warming’s impact on air quality. The analysis, published in 2017, estimates that an additional 1,130 Americans may die prematurely in the year 2030 from smog pollution under a scenario where global warming emissions are high and unchecked.100 The study also estimates that particulate pollution worsened by global warming could cause an extra 6,900 premature deaths in 2030.

In many cases, the activities that cause air pollution also contribute to global warming. Efforts to reduce our reliance on fossil fuels, which contribute to global warming, have the potential to help reduce ozone and particulate pollution as well.

Progress on air pollution has stalled. Though air quality in the U.S. has improved over the decades, in recent years that progress has slowed. The U.S. Environmental Protection Agency calculates that the average level of ozone pollution dropped by 31 percent from 1980 to 2018 and that fine particulate pollution dropped by 34 percent from 2000 to 2018.107 However, the agency’s analysis of elevated ozone and particulate pollution in 35 major cities shows that the number of days of pollution was higher in each of the years from 2015 through 2018 than it was in 2013 or 2014.108 Furthermore, the agency’s data show that 2018 had more days of pollution than each of the previous five years. The data analysis for this report reveals that the increase in days of elevated air pollution means that millions more Americans lived in areas with polluted air in 2018 than in 2016.109

There are of course a number of policy recommendations:

  • Support zero-emission vehicles
  • Create a strong regional program to reduce transportation emissions under the Transportation and Climate Initiative (TCI) in northeastern and mid-Atlantic states
  • Ensure that states can adopt and strengthen pollution standards for passenger vehicles
  • Maintain strong federal fuel economy and global warming pollution standards for transportation
  • Support policies that can reduce driving and increase walking, biking and the use of transit.
  • Supporting clean, renewable energy. Move the country away from fossil fuels – which are a major source of climate pollution in transportation, electricity generation and buildings – and toward the use of clean, renewable energy like wind turbines and solar panels.
  • Maintain the gains already achieved under implementation of the Clean Air Act
  • Strengthen ozone and particulate matter standards
  • Ensure strong enforcement of the Clean Air Act
  • Protecting and expanding urban tree cover

The references (superscript numbers) are listed in the original document:

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