How Does Air Quality Affect Health?
Key takeaways:
Air pollution is a known risk factor for heart and lung diseases, among others, and it increases deaths from every cause in adults and children.
Both short- and long-term exposure air pollution can increase your chances of heart attack and death.
More than 40% of Americans are living with unhealthy air pollution levels, according to the American Lung Association.
This week is Air Quality Awareness Week. Breathing healthy air is important for everyone, no matter their age and health. The bad news is that air pollution is a major public health threat. The World Health Organization (WHO) estimates that outdoor air pollution causes 4.2 million premature deaths every year.
The good news is that air pollution is a reversible public health threat. But we all have to play our part to reverse it.
Unfortunately, like with many other health threats, it disproportionately affects communities of color and low-income people who live and work in densely populated, highly urbanized areas with lower access to green, open spaces.
Read on to find out more about how air quality affects all of us, now and in future generations, and what we can do about it.
What is air quality and how is it measured?
Air quality is an assessment of how healthy the air is that you breathe. It is measured using the AQI, or air quality index. Air quality is based on the levels of many hazardous substances in our air. The WHO sets guidelines for what those levels should be for human health. Luckily, the Environmental Protection Agency (EPA) does the hard work for us by combining the complex scientific recommendations into an easy-to-understand, color-coded scale that helps us know how healthy our air is.
For anyone living in wildfire or smog-prone areas, you may be familiar with AQI values and how they affect what you can do and how you feel. But for many other people, the AQI may be something that you’ve never heard about before. We’ll explain.
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What do AQI values mean?
The AQI is a number between 0 and 500, where 0 is the best air quality possible and 500 is the worst air quality you could ever imagine. The AQI takes into account the levels of five common air pollutants, regulated by the Clean Air Act:
Ground level ozone
Particulate matter (PM)
Carbon monoxide
Sulfur dioxide
Nitrogen dioxide
There are six categories of AQI:
Green: 0 to 50 — good, with little or no risk to health
Yellow: 51 to 100 — acceptable
Orange: 101 to 150 — unhealthy for sensitive groups such as the elderly, children, and people of any age with heart or lung disease
Red: 151 to 200 — unhealthy for everyone
Purple: 201 to 300 — very unhealthy
Maroon: 301+ — hazardous
What causes air pollution?
Air pollution is caused by harmful particles and gases in the air. The substances can be both human-made and from natural sources. Here are some examples of sources of air pollution:
Vehicle emissions
Factories
Power plants
Industrial dusts
Central heating
Wood-burning stoves
Pollen
Wildfires
Volcanoes
Sometimes the particles and gases come directly from these sources. This is the case with particulate matter (PM) from wildfires, for example.
Other times, the pollutants are the result of chemical reactions that happen in the air. An example of this is ground level ozone, the main component of smog.
Ground level ozone
You may have heard of ozone. Ozone can be good or bad for our health, depending on where it is in the atmosphere. High up in the atmosphere, the ozone layer around our planet helps to protect us from the harmful effects of the sun. At ground level, though, ozone is a health threat. It can irritate the:
Eyes
Nose
Throat
Lungs
It also damages plant life, reducing the ability of trees and plants to remove carbon dioxide from our environment.
Ozone is also the main component of smog. Smog — that yellow-brownish layer of pollution that sits like a blanket over densely populated urban areas — is what happens when pollutants, such as those from vehicle exhaust fumes, react chemically when they are exposed to sunlight.
Particulate matter
Aside from ozone, particulate matter, or PM, is the other main component of smog. Particulate matter is particles that can be solid or liquid, and it hangs in the air that we breathe. These particles are chemicals such as:
Sulfates
Nitrates
Carbon
Mineral dusts
They come from burning fossil fuels to power cars, factories, and homes, as well as naturally occurring sources like wildfires and volcanic eruptions.
You can see some PM with your eyes, like ash and soot. But the most dangerous particles are so small you can’t see them. PM is classified according to the size of the particles:
Larger particles are those of size PM10 (diameter of 10 micrometers and less). They get caught in the natural filters of the nose and throat as we breathe them in.
Smaller particles are able to get right into the lungs and even into the bloodstream, where they cause damage. These smallest particles, PM2.5 (diameter 2.5 micrometers and less), are the most harmful to human health. These particles are 30 times thinner than a human hair!
Other causes of air pollution
The other causes of air pollution are gases that are harmful to health such as:
Nitrogen oxides
Carbon monoxide
Carbon dioxide
Sulfur oxides
Volatile organic compounds (VOCs)
Airborne lead
Polycyclic aromatic hydrocarbons (PAHs)
What are the factors that affect air quality?
Air quality is affected by what humans — or, in some cases, natural events — are doing to create air pollution, and how the environment responds to it. For example, road traffic, wildfires, and volcanic eruptions will all significantly affect air quality.
Then, environmental factors determine how badly the air quality will be affected. Air pollution levels can be worsened by:
Slow wind speed, or fast wind speed in the wrong direction
Higher temperatures
Strong sunlight
Higher levels of humidity
How air quality impacts health
According to the WHO, outdoor air pollution was responsible for 4.2 million deaths globally in 2016. And, as with many environmental risk factors that disproportionately affect communities of color, air pollution is no different. In the U.S., people of color are over 3 times more likely to be breathing polluted air than white people.
Long-term effects of air pollution
Breathing polluted air increases the risk of cardiovascular disease (heart attacks and strokes) and respiratory disease — including worse outcomes from COVID-19. Not only that, but many studies have also shown a link between high levels of fine particulate matter and increased risk of death from heart and lung disease.
This link is so well-established that the American Heart Association, the European Society of Cardiology, and the American Lung Association have all issued official statements on the link between air pollution and heart and lung health and the need for urgent action.
It’s not clear yet exactly how air pollution affects this risk of heart and lung disease and death. Experts have some theories, though. When these hazardous chemicals are absorbed into our bloodstream, they may increase blood pressure, increase the risk of blood clots, and cause atherosclerosis (fatty deposits in the arteries). All of these are causes of heart disease and strokes. Ozone, when breathed into the lungs, causes inflammation similar to a sunburn. And particle pollution triggers asthma attacks and increases the risk of lung cancer.
Here’s what else you need to know:
The link between air pollution and death shows a “dose-response.” A study of six U.S. cities showed that the higher the level of PM2.5 in the air, the higher the death rate.
But, in the follow-up study, the risk of death in that population improved when air quality improved.
When children are exposed to air pollution — before birth and in early childhood — their brain and lung development is affected, and they are more likely to get breathing problems like asthma later in life.
It’s not just sick kids we need to worry about. According to UNICEF, air pollution is a major contributor to the deaths of 600,000 children under the age of 5 every year.
Studies have also suggested a link between air pollution and Alzheimer’s disease, problems with female fertility, and a higher risk of miscarriage and other pregnancy complications — and even autism spectrum disorders.
Air pollution has short-term effects on health, too
You don’t have to have lived your whole life in Los Angeles (named the city with the worst ozone pollution in the U.S. for 21 of 22 years) to be at risk for air pollution-related health complications. Even short-term exposure to high levels of air pollution (especially particulate pollution and ozone) causes an increase in deaths and heart attacks.
Who is most affected by air pollution?
Air pollution is bad for everyone. But for certain people, even lower levels of air pollution are harmful.
These groups of people may feel especially sensitive to air pollution and need to be extra careful at even moderate AQI levels:
Anyone with heart disease, or risk factors for heart disease
Anyone who exercises or exerts themselves outdoors, including for work
Older adults, because of their risk of stroke, heart, and lung disease
Babies and children, because they are still developing, breathe faster, and take in more air than adults
What steps can I take to reduce my exposure to air pollution?
If you are sensitive to air pollution, or you are in a high-risk group, the best way to reduce your exposure to air pollution is to keep an eye on the AQI in your area.
If air pollution levels are low, then there is no need to limit your activities outside of the home. That said, you’ll want to make sure you limit the amount of time you spend in areas with higher air pollution, such as near busy roads and junctions.
On “bad air days,” the best thing you can do to look after your health is to stay indoors as much as possible, keep away from high-traffic and high-pollution areas (if possible), avoid any strenuous activity outdoors (if possible), and keep a close eye on local public health recommendations and the weather forecast.
Here are some tips and tricks for reducing your exposure to air pollution:
Time your commute so that you are traveling outside of rush hour.
If you are walking or cycling, avoid main roads as much as you can, and instead choose a route through quieter neighborhoods and, ideally, some green open spaces.
Even if you are driving, avoiding traffic-dense roads will help to reduce your exposure to exhaust fumes.
Avoid wood fires in your home.
Consider a HEPA (High-Efficiency Particulate Arrestance) air purifier in your home and office.
Even in places with good air quality, people can still experience health benefits from improvements in air quality. Find out what you can do to take a stand for environmental justice and improve our collective exposure to air pollution.
The bottom line
Poor air quality can put you at risk for a range of health issues and diseases, such as heart and lung disease, as well as asthma. This is true for people exposed to air pollution in both the long and short terms. Unfortunately, people of color and those living in lower-income areas are more exposed to air pollution. And those who are more sensitive to air pollution, like those with pre-existing conditions and the elderly, are more at risk. However, it’s a problem that can be reversed. Check your AQI before heading outside for work or exercise.
Why trust our experts?
