Air pollution refers to the contamination of our air with harmful gases and particulates. Globally, 9 out of 10 people breathe polluted air but many people are unaware of the potential health and environmental impacts of poor air quality. Here’s what you need to know.
Air pollution is caused when harmful gases and chemicals are released into the air. These pollutants include Particulate Matter (very small particles that get into our respiratory system), nitrogen oxide and sulphur dioxide.
The majority of these pollutants are emitted through human activities like burning fossil fuels, vehicle exhaust fumes and emissions from agriculture and industry.
How does air pollution affect our health?Air pollution has a huge impact on our health, reducing quality of live and cutting lives short. In fact, it’s the world’s largest single environmental health risk. It aggravates breathing conditions and increases the risk of asthma attacks leading to more hospital admissions. Prolonged exposure can cause serious medical conditions, such as cancer, heart attacks and strokes. In fact, one in three deaths from strokes, lung cancer and chronic respiratory disease globally are caused by air pollution.
While we are all affected, those who are the most vulnerable in our society are more at risk, especially children and older people. Exposure to air pollution can cause children to develop breathing conditions and stunted lungs.
There is also a growing body of research linking air pollution to other illnesses, including diabetes, developmental problems for children and suggested links to dementia.
Watch Dr Zoe Williams explain how air pollution impacts our bodies, long-term health and children
How does air pollution affect the environment?A great number of air pollution sources are also those of greenhouse gas (GHG) emissions. Greenhouse gases cause the Earth’s heat to be trapped in the atmosphere, which leads to warmer temperatures, exacerbating climate change.
Air pollution can also impact the quality of soil and water, impacting ecosystems and wildlife.
How can we reduce air pollution?We need policies and laws in place that protect people’s health and support the shift to cleaner alternatives. At ClientEarth, we’ve taken legal action to combat pollution and fight for clean air in 11 countries across Europe. We’re calling on the UK government to introduce stronger clean air laws to better protect people’s health. We’re also working to design more stringent EU laws that will have an impact in all EU Member States.
How can you avoid air pollution?Avoid busy roads and high traffic areas, where possible, try to walk on the side of the pavement furthest from the road and choose routes through green spaces. The further you are from traffic, the lower the pollution levels.
If you suffer from lung conditions, avoid doing strenuous exercise on high pollution days.
Air pollution is a familiar environmental health hazard. We know what we’re looking at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack. Some air pollution is not seen, but its pungent smell alerts you.
It is a major threat to global health and prosperity. Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, a number that has increased over the past two decades.
What Is Air Pollution?
Air pollution is a mix of hazardous substances from both human-made and natural sources.
Vehicle emissions, fuel oils and natural gas to heat homes, by-products of manufacturing and power generation, particularly coal-fueled power plants, and fumes from chemical production are the primary sources of human-made air pollution.
Nature releases hazardous substances into the air, such as smoke from wildfires, which are often caused by people; ash and gases from volcanic eruptions; and gases, like methane, which are emitted from decomposing organic matter in soils.
Traffic-Related Air Pollution (TRAP), a mixture of gasses and particles, has most of the elements of human-made air pollution: ground-level ozone, various forms of carbon, nitrogen oxides, sulfur oxides, volatile organic compounds, polycyclic aromatic hydrocarbons, and fine particulate matter.
Ozone, an atmospheric gas, is often called smog when at ground level. It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in the presence of sunlight.
Noxious gases, which include carbon dioxide, carbon monoxide, nitrogen oxides (NOx), and sulfur oxides (SOx), are components of motor vehicle emissions and byproducts of industrial processes.
Particulate matter (PM) is composed of chemicals such as sulfates, nitrates, carbon, or mineral dusts. Vehicle and industrial emissions from fossil fuel combustion, cigarette smoke, and burning organic matter, such as wildfires, all contain PM.
A subset of PM, fine particulate matter (PM 2.5) is 30 times thinner than a human hair. It can be inhaled deeply into lung tissue and contribute to serious health problems. PM 2.5 accounts for most health effects due to air pollution in the U.S.
Volatile organic compounds (VOC) vaporize at or near room temperature—hence, the designation volatile. They are called organic because they contain carbon. VOCs are given off by paints, cleaning supplies, pesticides, some furnishings, and even craft materials like glue. Gasoline and natural gas are major sources of VOCs, which are released during combustion.
Polycyclic aromatic hydrocarbons (PAH) are organic compounds containing carbon and hydrogen. Of more than 100 PAHs known to be widespread in the environment, 15 are listed in the Report on Carcinogens. In addition to combustion, many industrial processes, such as iron, steel, and rubber product manufacturing, as well as power generation, also produce PAHs as a by-product. PAHs are also found in particulate matter.
Air Pollution and Climate Change
Air pollution and climate change affect each other through complex interactions in the atmosphere. Air pollution is intricately linked with climate change because both problems come largely from the same sources, such as emissions from burning fossil fuels. Both are threats to people’s health and the environment worldwide. Read more: Health Impacts of Air Quality.
Over its 50-plus year history, NIEHS has been a leader in air pollution research. The institute continues to fund and conduct research into how air pollution affects health and the population groups who are most affected.
When the National Ambient Air Quality Standards were established in 1970, air pollution was regarded primarily as a threat to respiratory health. In 1993, NIEHS researchers published the landmark Six Cities Study, which established an association between fine particulate matter and mortality.
Air pollution exposure is associated with oxidative stress and inflammation in human cells, which may lay a foundation for chronic diseases and cancer. In 2013, the International Agency for Research on Cancer of the World Health Organization (WHO) classified air pollution as a human carcinogen.
Research on air pollution and health effects continually advances. Public health concern now includes cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders
The NIEHS-funded Children’s Health Study at the University of Southern California is one of the largest studies of the long-term effects of air pollution on children’s respiratory health. Among its findings:
Other studies on women and children
Your genes play a role in respiratory health. NIEHS-funded research discovered that people with specific gene variants, which made them more likely to have lung inflammation, had a greater chance of suffering from asthma if they lived close to major roadways.
NIEHS supports community participation in the research process and encourages collaborative approaches that build capacity in communities to address environmental health concerns. Community-engaged research and citizen science are two types of collaborative research approaches.
For example, NIEHS helps residents of Imperial County, California track air pollution through a network of 40 community-run monitors. In this county, long-term improvements in air quality were associated with significant lung-function improvement in children.
In another example, NIEHS grant recipients developed community-level tactics and public policies for reducing exposure to TRAP:
THE (Trade, Health, Environment) Impact Project brings together researchers and community groups to find solutions for communities affected by trade-related pollution, such as ports and roadways with trucking.
Credit: NASA/JPL-Caltech
Air pollution happens when solid and liquid particles—called aerosols—and certain gases end up in our air. These particles and gases can be bad for the planet and for our health, so keeping track of them is important.
Where do aerosols come from?
Any particle that gets picked up into the air or is formed from chemical reactions in the air can be an aerosol. Many aerosols enter the atmosphere when we burn fossil fuels—such as coal and petroleum—and wood. These particles can come from many sources, including car exhaust, factories and even wildfires. Some of the particles and gases come directly from these sources, but others form through chemical reactions in the air.
Aerosols can come from other places, too, such as ash from an erupting volcano. Dust, pollen from plants and mold spores are also examples of aerosols.
This animation uses NASA data to show how ash from a volcano in Chile travels around the world in our atmosphere. Credit: NASA's Goddard Space Flight Center
What else causes air pollution?
Certain gases in the atmosphere can cause air pollution. For example, in cities, a gas called ozone is a major cause of air pollution. Ozone is also a greenhouse gas that can be both good and bad for our environment. It all depends where it is in Earth’s atmosphere.
Credit: NASA/JPL-Caltech
Ozone high up in our atmosphere is a good thing. It helps block harmful energy from the Sun, called radiation. But, when ozone is closer to the ground, it can be really bad for our health. Ground level ozone is created when sunlight reacts with certain chemicals that come from sources of burning fossil fuels, such as factories or car exhaust.
When particles in the air combine with ozone, they create smog. Smog is a type of air pollution that looks like smoky fog and makes it difficult to see.
Smog is a type of air pollution in cities that makes it difficult to see outside. Here are images of Beijing on a clear day after a rain (left) and on a smoggy day (right). Credit: Bobak via Wikimedia Commons CC BY-SA 2.5
How does air pollution affect Earth’s climate?
Aerosols can impact how the Sun’s light hits Earth. For example, some aerosols reflect sunlight while others absorb sunlight. It depends on the color of the particle.
Credit: NASA/JPL-Caltech
Dark surfaces—whether it’s a black t-shirt or a dark particle in the atmosphere—absorb the Sun's heat. Lighter-colored surfaces reflect heat from the Sun.
A white t-shirt reflects the Sun on a hot day, making you feel cooler. In the same way, light-colored particles that reflect the Sun’s light and heat away from Earth can make the global temperature cooler. Dark-colored particles that absorb the Sun’s light can make the global temperature warmer.
How does air pollution affect our health?
Breathing in polluted air can be very bad for our health. Long-term exposure to air pollution has been associated with diseases of the heart and lungs, cancers and other health problems. That’s why it’s important for us to monitor air pollution.
How is NASA monitoring air pollution?
NASA uses satellites orbiting Earth to keep an eye on air pollution. In fact, air quality forecasters use information about aerosols from NASA’s Aqua, Terra and Suomi-NPP satellites.
NASA also is developing a new instrument called the Multi-Angle Imager for Aerosols, or MAIA, to fly aboard a future spacecraft mission. MAIA will help scientists understand the size, makeup and quantity of aerosols in our air. Eventually, scientists will be able to compare this information with health records. This can help us better understand the relationship between aerosol pollution and human health.
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