A Clear Skies Playbook
Almost four years ago to the date, the world went through an unintentional experiment in reducing air pollution with the covid-19 pandemic lockdowns. Almost overnight, vehicle and air traffic reduced worldwide, population movements stopped, economic activity slowed, and scenes like the ones below were seen across the world. Megacities across the world, including in the U.S. and Asia, saw clear skies that seemed impossible to imagine before the unprecedented collective act of responding to a global pandemic. While the covid-19 lockdowns saved lives and temporarily reduced air pollution, it did so at a huge economic cost that everyone bore to save lives during the acute stage of the covid-19 pandemic. It begs the question — is it possible to have such clean air without such a painful economic cost in normal times?
Human Health Impacts of Air Pollution
While the world was battling the covid-19 pandemic in 2020, an important research paper from a team from the German Center for Cardiovascular Research showed that the global average Loss of Life Expectancy (LLE) of 2.9 years from ambient air pollution was greater than for other risk factors including tobacco smoking (2.2 years), HIV/AIDS (0.7 years), parasitic and vector-borne diseases (0.6 years), and all forms of violence (0.3 years). The loss of life expectancy occurs because air pollution exacerbates cardiovascular and respiratory diseases, lung cancer, and lower respiratory tract infections. Note that the global average LLE metric masks important differences across countries for each of these human health problems. Researchers have also found that air pollution has a significant effect on the brain development of children and adult cognition, having the effect of the loss of one year of education.
Some of the greatest reductions in life expectancy due to air pollution are in areas with high population density from power plants, vehicle tailpipe emissions, and other man-made or naturally-occurring factors depending on the region, like dust from construction, wildfires, or sand storms. Air pollution reduces life expectancy globally, including in the eastern U.S. and a few west coast cities, much of the UK, Germany, Eastern Europe, the Middle East, the Ivory Coast region of Africa, as well as near the megacities of India, China, Japan, and much of East Asia as shown in the map below of excess mortality estimates from air pollution across the world.
This study showed that air pollution is one of the biggest sources of excess deaths in the world, at 8.8 million/yr as compared to the 14.8 million deaths during the 2020–2021 period of the covid-19 pandemic. Air pollution as a source of excess mortality will only continue or worsen without interventions at the personal, business, and policy level.
Science of Air Pollution
Air pollution occurs through gaseous emissions from vehicle transportation, power plants, industrial and agricultural activity. Common air pollution has many constituents, including ozone, noxious gases, volatile organic compounds, particulate matter, and polycyclic aromatic hydrocarbons:
- Ozone, also known as smog when occurring at the ground level, occurs when pollutants react with sunlight.
- Noxious gases include nitrous oxides (NOx), sulfur oxides (SOx), carbon monoxide, and carbon dioxide.
- Volatile organic compounds have both biogenic and artificial sources, often have a strong scent (either pleasant or not), contain carbon, evaporate at room temperature, and are off-gassed from common household items including personal care products, paint, cleaning supplies, pesticides, some furnishings, and glues, and differ in human health impacts and are an active area of research.
- Gasoline and natural gas release significant amounts of VOCs through combustion.
- Polycyclic aromatic hydrocarbons contain hydrogen and carbon and are released through combustion, and the manufacturing of iron, steel, rubber products, and through power generation.
- Particulate matter, also known as soot, is solid or liquid matter in aerosol form and commonly measured at 2.5 micron or 10 micron size, and are especially problematic for health.
Air pollution is a problem that originates locally and is common in many places of the world, with pollution sources that differ according to the local economy and business regulations. Most air pollution is released from mobile sources (cars, trucks, buses), stationary sources (factories, refineries, power plants), and indoor sources (building materials, cooking, and cleaning). In some regions, construction practices and farming activity can also be a major source of air pollutants. In the United States, the U.S. EPA measures or models the air pollution releases from various sources as well as ambient air quality and sets regulations on industrial sectors based on the latest scientific assessments, pollutant risks and exposure levels, and a policy assessment including stakeholder input. States also measure local air quality, and the state of California has a waiver to set air quality standards as stringent as or more so than federal standards based on the extraordinary smog conditions in Los Angeles and the Central Valley, which it has done even before federal air quality standards were adopted.
Reducing Air Pollution Effects
There are many approaches to reduce air pollution and its effects on human health. First, one could reduce one’s exposure to air pollution by not smoking, seeking medical care for any air pollution-related health issues, and limiting strenuous activity outdoor activity to green or yellow days according to the EPA’s Air Quality Index. The AQI is a yardstick that measures the amount of six common air pollutants (ground-level ozone, PM2.5 and PM10, carbon monoxide, sulfur dioxide, nitrogen dioxide) that are harmful to human health and provides recommendations for acceptable outdoor activity level at different levels of air pollution. The EPA has a mobile app to monitor local air pollution where you live based on measurements from air pollution monitoring instruments collecting emissions levels from stationary sources and measuring ambient air quality. A commercial sensor manufacturer has also compiled a map of air quality based on its sensor products.
Second, one could reduce air pollution sources under one’s control (from both outdoor and indoor sources), by taking actions such as reducing driving or taking public transport, driving an electric or hybrid electric vehicle which result in lower tailpipe air pollution emissions, using renewable energy sources for electricity, through using solar panels, batteries, electric heat pumps, and electric cooking, and using organic cleaning supplies to reduce harmful volatile organic compound (VOC) exposure. Cooking is a major source of indoor air pollution in homes, exposure to which can be reduced through good fans and household ventilation systems. Many consumer-grade air filters also exist to control indoor air pollution sources. Research is also underway to study the effect of trees to reduce air pollution impacts on people. Companies can minimize air pollution liabilities by following worker health and environmental laws, using non-toxic materials where possible, and investing in building ventilation systems.
Lastly, one could support policies to reduce air pollution in the environment such as the U.S. Clean Air Act. The Clean Air Act, enacted in 1963, with the goal of reducing and controlling air pollution nationwide through setting National Ambient Air Quality Standards for the six common outdoor air pollutants as well as standards for 187 other toxic pollutants from industrial facilities through subsequent amendments. One of the major accomplishments of the Clean Air Act is to solve the acid rain problem through an emissions trading program.
The covid-19 lockdowns, while challenging on many levels, provided a unique and unexpected view of a cleaner air future largely through changes in mobility choices. Think of what is possible through active investment and policy to support clean air and transportation.
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