Back to Basics, Chemicals, Health and Wellness, Sustainability

Back to Basics: Hazardous Air Pollution

Back to Basics is a weekly feature that highlights important but possibly overlooked information that any EHS professional should know. This week, we examine hazardous air pollution and the EPA’s strategies for dealing with climate change.

Following the train derailment in East Palestine, Ohio, that happened in early February, the Environmental Protection Agency (EPA) has been providing updates on how it is conducting air monitoring. Air pollution harms people’s health and the environment, and under the Clean Air Act, the EPA continues to work with state, local, and tribal governments, other federal agencies, and stakeholders to reduce air pollution and the damage that it causes. There are many challenges the agency faces when dealing with air pollution.

Common pollutants

In recent years, the EPA has revised standards for five of the six common pollutants subject to national air quality standards, making them more protective because new studies have shown that existing standards were not adequate enough to protect public health and the environment.

According to the EPA, pollution levels in many areas of the United States exceed national air quality standards for one of these six common pollutants:

  • Fine particle pollution
  • Ground-level ozone pollution
  • Sulfur dioxide
  • Nitrogen dioxide
  • Lead
  • Carbon monoxide

Fine particle and ground-level ozone pollution levels are lower than in the past, but they are still unhealthy. Both pollutants are caused by emissions from multiple sources, and they travel long distances and across state lines.

Long- and short-term exposure to fine particulate matter (PM) can cause premature death and harm to the cardiovascular system, which means increased hospital admissions and emergency department visits for heart attacks and strokes. Evidence also suggests that fine particulate matter contributes to respiratory issues, including asthma attacks.

Ground-level ozone can cause shortness of breath, increase the amount and frequency of asthma attacks, aggravate lung diseases, and cause permanent lung damage with long-term exposure. Both pollutants cause environmental damage, and fine particles impair visibility.

Sulfur dioxide and nitrogen dioxide pollutants cause many negative respiratory effects, including more asthma symptoms, and are associated with more hospital visits for respiratory illnesses. Both of them are byproducts of fossil fuel combustion and cause environmental damage.

Airborne lead pollution now meets the national air quality standards except in areas near certain large lead-emitting industrial facilities. Lead is associated with neurological effects in children, such as behavioral problems, learning deficits, and lowered IQ. It also has been known to cause high blood pressure and heart disease in adults.

In the case of carbon monoxide, the EPA says the entire United States meets the air quality standards, mostly because of emissions standards for new motor vehicles under the Clean Air Act.

Climate change

Emissions of carbon dioxide and other long-lived greenhouse gases that build up in the atmosphere endanger the health and welfare of current and future generations by causing climate change and oceans acidification, says the EPA. Carbon dioxide, methane, nitrous oxide, and fluorinated gases trap heat in the atmosphere, and are produced by several different human activities.

Climate change creates many substantial risks to public health and the environment, including more intense hurricanes and storms, heavier and more frequent flooding, increased drought, and more severe wildfires. All of these disasters will affect people and businesses, and cause deaths, injuries, and billions of dollars of damage to property and the country’s infrastructure.

Carbon dioxide and greenhouse gas pollution leads to more frequent and intense heat waves that also increase fatalities, especially among the poor and elderly populations. Scientists also expect an increase in ground-level ozone pollution, the spread of waterborne and pest-related diseases, and production and dispersion of airborne allergens.

The other effects of climate change include ocean acidification, rising sea levels, increased storm surges, harm to agriculture and forests, species extinctions, and ecosystem damage. All of these issues will affect human issues such as food scarcity, mass migration, trade, and national security. The populations most disproportionately affected include children, the poor, the elderly, and future generations. Certain communities, such as low-income communities and communities of color are disproportionately impacted by heat waves, degraded air quality, and extreme weather events.

The EPA has taken several approaches to combating greenhouse gas pollution, including setting emission standards for motor vehicles and stationary sources such as power plants, refineries, cement plants, and steel mills.

Toxic pollutants

Hazardous air pollutants, also called air toxics, include 187 pollutants listed in the Clean Air Act. The EPA can add pollutants that are known or suspected to cause cancer and other serious health effects, such as reproductive issues or birth defects, or to cause adverse environmental effects. Some examples of air toxics include the following:

  • Benzene
  • Perchloroethylene
  • Methylene chloride
  • Dioxin
  • Asbestos
  • Cadmium
  • Mercury
  • Chromium
  • Lead compounds

Most air toxics come from manmade sources, including motor vehicles, industrial facilities, and small “area” sources. Power plants, chemical manufacturing, aerospace manufacturing, and steel mills are all stationary sources that emit air toxics. Forest fires also release large amounts of air toxics.

According to the EPA, the U.S. experiences lifetime cancer risks above 10 in a million and almost 14 million people in more than 60 urban locations have risks greater than 100 in a million, all due to inhalation risks from air toxics. The higher risk areas are large urban areas where there are multiple emissions sources, communities near industrial facilities, or areas near large roadways or transportation facilities.

The EPA has completed standards for 174 major source categories, and 68 small area source categories representing 90% of emissions of 30 priority pollutants for urban areas. The agency has also reduced the benzene content in gasoline, and established strict emission standards for on-road and nonroad diesel and gasoline engine emissions that significantly reduce emissions of mobile source air toxics.

Ozone layer protection

The ozone layer in the stratosphere protects life on earth by filtering out harmful ultraviolent radiation (UV) from the sun, and when chlorofluorocarbons (CFC) and other ozone-degrading chemicals are emitted, the mix with the atmosphere and eventually rise to the stratosphere.

There, the chlorine and bromine they contain cause chemical reactions that destroy the ozone. The destruction of the ozone layer is occurring at a more rapid rate than ozone can be created through natural processes, meaning that the ozone layer is being depleted.

The effects of higher levels of UV radiation reaching Earth’s surface include health and environmental effects such as a greater incidence of skin cancer, cataracts, and impaired immune systems. Higher UV radiation levels also reduce crop yields, diminish the productivity of the oceans, and possibly contribute to the decline of amphibious populations throughout the world.

Countries around the world are phasing out the production of chemicals that destroy the ozone layer under an international treaty called the Montreal Protocol, says the EPA. The U.S. has already phased out production of the substances, including CFCs, halons, methyl chloroform, and carbon tetrachloride, that have the greatest potential to deplete the ozone layers under Clean Air Act provisions enacted to implement the Montreal Protocol.

The U.S. and other countries are also phasing out production of hydrofluorocarbons (HCFC), which are chemicals being used globally in refrigeration and air-conditioning equipment, and in making foams. CFCs and HCFCs are also very damaging greenhouse gases, so phasing them out is beneficial to protecting the earth’s climate.

According to the EPA, the Clean Air Act implements regulatory programs to ensure that refrigerants and halon fire extinguishing agents are recycled properly and that alternatives to ozone-depleting substances (ODS) are evaluated for their impacts on human health and the environment. The programs also ban the release of ozone-depleting refrigerants during the service, maintenance, and disposal of air conditioners and other refrigerant equipment, and require that manufacturers label products that either contain or are made with the most harmful ODS.

These measures are vital to protecting human health and the global environment. However, the work of protecting the ozone layer is not finished, and in an effort to continue it, the EPA plans to continue to provide forecasts of the expected risk of overexposure to UV radiation from the sun through the UV index, and to educate the public on how to protect themselves from overexposure. The agency will also continue to foster domestic and international partnerships to protect the ozone layer, and encourage the development of products, technologies, and initiatives that reap co-benefits of climate change and energy efficiency.

For more information on the EPA’s air pollution efforts, click here.

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