Air pollution is shortening lives worldwide | Science News for Students

Air pollution is shortening lives worldwide

The average life span is a year shorter due to tiny particles in the air people breathe
Sep 14, 2018 — 6:45 am EST
a satellite image of air pollution over India

This satellite photo shows air pollution over India, where it shortens the average life span by about 1.5 years.

NESDIS/NOAA

Air is free. But breathing dirty air has a price. Indeed, it can cost someone’s life span months — even years, a new study finds.

Worldwide, air pollution lowers average life spans by a year. In more polluted parts of Asia and Africa, dirty air shortens lives up to twice that much. Scientists shared their new findings August 22 in Environmental Science & Technology Letters.

The study used data gathered in 2016 as part of a project known as the Global Burden of Disease. It was the first major country-by-country look at the link between life spans and what’s known as fine PM (PM is short for particulate matter). Less than 2.5 micrometers across, these bits of pollution are less than one-thirtieth the width of an average human hair. Such pollution is known as PM2.5. 

Air pollution has been linked to many health problems. Among them are lung and heart diseases. Most earlier studies had looked at how tiny air pollutants affected rates of illness or death. But when you talk about such rates, “you see people’s eyes glaze over,” says Joshua Apte. He’s an environmental scientist at the University of Texas at Austin. By instead looking at life expectancy, his team had hoped to make the threat easier to understand.

“People,” he explains, “care not just about whether you die — we all die — but also how much younger are you going to be when that happens.”

All countries suffer

Pollution makes a difference even in countries with relatively clean air, such as the United States and Australia. Even the low levels of PM2.5 in them costs their average residents a few months of their lives.


A Flourish data visualization


PM2.5 is what scientists call tiny particles of pollution in the air. Higher levels of PM2.5 can cause health problems and cut months, if not years, from the average life span. This analysis, based on 2016 data, shows how pollution affects life expectancy in different parts of the world. Each dot represents a country. 

Credit: E. Otwell; Data source:  J.S. Apte 2018 et al/Environmental Science & Technology Letters 2018 


The World Health Organization (WHO) recommends limiting PM2.5 to 10 micrograms per cubic meter of air. Apte’s group calculated how holding pollution to this low level would help people. Some high-income countries, including Canada, already keep their air this clean. But others, typically in fairly poor countries, have far higher pollution levels.

Egyptians, for example, could gain back about 1.3 years of life on average by meeting the WHO standard, the study calculated. Life spans in China would increase by an average of about nine months.

But meeting the WHO standard won’t eliminate health costs from dirty air. That’s because even below 10 micrograms per cubic meter, pollution still causes significant risks.

India is has some of the world’s worst air pollution. There, clearing the air to WHO standards would up the chances by 20 percent that a 60-year-old person would live another 25 years, the authors say.


How cleaning up the air can lengthen lives


Made with Flourish

Reducing air pollution could increase life expectancy. This map shows what would happen if every country limited fine particles in the air to 10 micrograms per cubic meter. That’s the limit the World Health Organization recommends. In countries with very dirty air, that change would lengthen people’s lives. In countries whose air already meets this standard, the map shows no gain in life expectancy. That’s because even very low levels of pollution can still harm health.

Credit: E. Otwell; Data source:  J.S. Apte 2018 et al/Environmental Science & Technology Letters 2018 


The scientists also compared how other threats shorten life spans across the globe. These risk factors included smoking and cancer. In South Asia (which includes India, for example), they found PM2.5 had a bigger effect on life expectancy than did all cancers combined! 

These results show that in poor countries, cleaning up dirty air could greatly boost life spans. It could have as big an effect as cleaning up drinking water, or curing breast cancer or lung cancer. In wealthier countries, the opposite is true. Air pollution shortens life expectancy in these countries by less than half a year. But all forms of cancer shorten the average life in wealthier countries by more than 3.5 years.

Knowing this “can really help people, or policy makers, decide where to spend their money,” says Kirk Smith. He studies global environmental health at the University of California, Berkeley. Smith was not involved in the study.


Made with Flourish

Fine particulate air pollution, or PM2.5, is just one of many common health risks. But in some places, this pollution shortens people’s lives by more than other problems like lung cancer or poor water quality. 

Credit: E. Otwell; Data source:  J.S. Apte 2018 et al/Environmental Science & Technology Letters 2018 


Similar research has treated all countries and populations the same. The new study doesn’t. It shows how air pollution affects how long people are likely to survive in a given country. Each country has a different baseline level of health. For example, Russia and Ukraine have relatively old and unhealthy populations. Even though these countries have fairly low pollution, cleaning up their air might greatly boost life spans.

In 42 countries — mostly in Africa and Asia —  PM2.5 shortened life spans by a year or more. Imagine having an extra year with the people in your life who matter most. Clearly, Apte says, “Everybody benefits when the air is improved.”

Power Words

(for more about Power Words, click here)

average     (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

cancer     Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.

environmental health     A research field that focuses on measuring the effects of pollutants and other factors in the environment on the health of people, wildlife or ecosystems.

environmental science     The study of ecosystems to help identify environmental problems and possible solutions. Environmental science can bring together many fields including physics, chemistry, biology and oceanography to understand how ecosystems function and how humans can coexist with them in harmony. People who work in this field are known as environmental scientists.

factor     Something that plays a role in a particular condition or event; a contributor.

link     A connection between two people or things.

micrometer     (sometimes called a micron) One thousandth of a millimeter, or one millionth of a meter. It’s also equivalent to a few one-hundred-thousandths of an inch.

particulate     A tiny bit of something. A term used by pollution scientists to refer to extremely tiny solid particles and liquid droplets in air that can be inhaled into the lungs. So-called coarse particulates are those with a diameter that is 10 micrometers or smaller. Fine particulates have a diameter no bigger than 2.5 micrometers (or 2,500 nanometers). Ultra-fine particulates tend to have a diameter of 0.1 micrometer (100 nanometers) or less. The smaller the particulate, the more easily it can be inhaled deeply into the lungs. Ultra-fine particulates may be small enough to pass through cell walls and into the blood, where they can then move throughout the body.

policy     A plan, stated guidelines or agreed-upon rules of action to apply in certain specific circumstances. For instance, a school could have a policy on when to permit snow days or how many excused absences it would allow a student in a given year.

pollutant     A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

population     (in biology) A group of individuals from the same species that lives in the same area.

resident     Some member of a community of organisms that lives in a particular place. (Antonym: visitor)

risk     The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)

smoking     A term for the deliberate inhalation of tobacco smoke from burning cigarettes.

standards     (in pollution regulations) A limit above which something may not be used, sold or considered safe.

technology     The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.

World Health Organization     An agency of the United Nations, established in 1948, to promote health and to control communicable diseases. It is based in Geneva, Switzerland. The United Nations relies on the WHO for providing international leadership on global health matters. This organization also helps shape the research agenda for health issues and sets standards for pollutants and other things that could pose a risk to health. WHO also regularly reviews data to set policies for maintaining health and a healthy environment.

Citation

Journal: J.S. Apte et al. Ambient PM2.5 reduces global and regional life expectancyEnvironmental Science & Technology Letters. Published online August 22, 2018. doi:10.1021/acs.estlett.8b00360.