Air Pollution and Your Health

Air Pollution
It is a familiar environmental health hazard.  We know what we look at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack.  Some air pollution cannot be seen, but its pungent smell alerts you.  It is a significant threat to global health and prosperity.  Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, which has increased over the past two decades.

Air Pollution and Your Health
By Pierre Mouchette | Bits-n-Pieces

Air Pollution
It is a familiar environmental health hazard.  We know what we look at when brown haze settles over a city, exhaust billows across a busy highway, or a plume rises from a smokestack.  Some air pollution cannot be seen, but its pungent smell alerts you.  It is a significant threat to global health and prosperity.  Air pollution, in all forms, is responsible for more than 6.5 million deaths each year globally, which has increased over the past two decades.
 
What Is Air Pollution?
Air pollution is a mix of human and natural hazardous substances. 
Human-made air pollution - 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.
Nature - releases hazardous substances into the air, such as smoke from wildfires, which people often cause; ash and gases from volcanic eruptions; and gases, like methane, emitted from decomposing organic matter in soils.
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.
Ozone - an atmospheric gas, often called smog, when it is at ground level.  It is created when pollutants emitted by cars, power plants, industrial boilers, refineries, and other sources chemically react in sunlight.
Particulate matter (PM) - comprises chemicals such as sulfates, nitrates, carbon, or mineral dust.  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, contributing to serious health problems.  PM 2.5 accounts for most health effects due to air pollution in the U.S.
Polycyclic aromatic hydrocarbons (PAH) - are organic compounds containing carbon and hydrogen.  Of the more than 100 PAHs known to be widespread in the environment.  In addition to combustion, many industrial processes, such as iron, steel, and rubber manufacturing and power generation, produce PAHs as a by-product.  PAHs are also found in particulate matter.
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.
Volatile organic compounds (VOC) - vaporize at or near room temperature, hence the designation of 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 primary sources of VOCs, which are released during combustion.
 
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 primarily from the same sources, such as emissions from burning fossil fuels.  Both are threats to human health and the environment worldwide.  
 
How does air pollution affect our health?
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 concerns now include cancer, cardiovascular disease, respiratory diseases, diabetes mellitus, obesity, and reproductive, neurological, and immune system disorders.
Cancer

• A large study of more than 57,000 women found living near major roadways may increase a woman’s risk for breast cancer.
• A long-term study, 2000-2016, found an association between lung cancer incidence and increased reliance on coal for energy generation.
• Occupational exposure to benzene, an industrial chemical and component of gasoline, can cause leukemia and is associated with non-Hodgkin’s Lymphoma.
• The NIEHS Sister Study found that other airborne toxic substances, especially methylene chloride, which is used in aerosol products and paint removers, are also associated with an increased risk of breast cancer.

Cardiovascular Disease

• According to a National Toxicology Program (NTP) report, TRAP exposure also increases a pregnant woman’s risk for dangerous changes in blood pressure, known as hypertensive disorders, which are a leading cause of pre-term birth, low birth weight, and maternal and fetal illness and death.
• Fine particulate matter can impair blood vessel function and speed up calcification in arteries.
• For some older Americans, exposure to TRAP can result in lowered levels of high-density lipoprotein, sometimes called good cholesterol, increasing their risk for cardiovascular disease.
• NIEHS researchers established links between short-term daily exposure by post-menopausal women to nitrogen oxides and increased risk of hemorrhagic stroke.

Respiratory Disease

• Air pollution can affect lung development and is implicated in the development of emphysema, asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD).
• Asthma prevalence and severity increases are linked to urbanization and outdoor air pollution.  Children living in low-income urban areas tend to have more asthma cases than others.  Research published in 2023 tied two air pollutants, ozone and PM2.5, to asthma-related changes in children’s airways.
• PM and nitrogen oxide are linked to chronic bronchitis.
• In 2020, a significant public health challenge was the confluence of the COVID-19 pandemic and wildfires across the western U.S.  Building on a well-established connection between air pollution and respiratory tract infections, a study linked wildfire smoke with additional COVID-19 cases and deaths.

 
Who does air pollution affect the most?
Air pollution affects everyone’s health, but certain groups may be harmed more.  Almost 9 out of 10 people who live in urban areas worldwide are affected by air pollution.
Children
The NIEHS-funded Children’s Health Study at the University of Southern California is one of the most extensive studies of the long-term effects of air pollution on children’s respiratory health.
Among its findings:

• Children living near busy roads are at increased risk for asthma.
• Children playing several outdoor sports and living in high-ozone communities are more likely to develop asthma.
• Children with asthma exposed to high levels of air pollutants were more likely to develop bronchitis symptoms.
• Higher air pollution levels increase short-term respiratory infections, which lead to more school absences.
• Living in communities with higher pollution levels can cause lung damage.

 
Why improving air quality matters
Air pollution and birth outcomes are linked as global public health concerns. Researchers analyzed indoor and outdoor air pollution data from all inhabited continents along with key pregnancy outcomes. Their findings indicate that reducing PM2.5 exposure could significantly reduce the number of infants with low birth weight and pre-term birth worldwide. Air pollution reduction would be especially beneficial for children born in low- and middle-income countries.
Among children in Southern California, decreases in ambient nitrogen dioxide and PM 2.5 were associated with fewer cases of asthma.
An NIEHS-funded study found that a mixture of several B vitamins may protect DNA from changes attributable to PM 2.5 air pollution.
Bronchitis symptoms declined as pollution levels dropped in the Los Angeles region.
Improving air quality may improve cognitive function and reduce dementia risk, according to studies supported partly by NIH and the Alzheimer's Association.
When fossil-fuel power plants close, nearby air pollution is reduced.  A study found preterm births decreased within 5 kilometers of retired coal and oil-powered plant locations.