Air pollution is shaving a year off our average life expectancy

In some regions, fine particulate matter affects mortality more than breast or lung cancer

1:35PM, AUGUST 22, 2018
air pollution over India

SHORTER LIVES  Air pollution over India (seen in this satellite photo) shortens the average life span there by about 1.5 years. A new study calculates how much fine particulate matter pollution hurts life expectancy in 185 countries.

Breathing dirty air exacts a price — specifically, months, or even years, off of life.

On average worldwide, air pollution shaves a year off of human life expectancy, scientists report August 22 in Environmental Science & Technology Letters. In more polluted regions of Asia and Africa, lives are shortened by 1.5 to two years on average.

The study, using 2016 country data from the Global Burden of Disease project, is the first major look at country-specific life expectancy impacts of fine particulate matter — bits of pollution, known as PM2.5,  that are smaller than 2.5 micrometers, or 30 times smaller than the width of an average human hair. Most other studies present such air pollution impacts in terms of death or disease rates (SN: 11/25/17, p. 5). The new approach is aimed at making the risk more relatable, says Joshua Apte, an environmental scientist at the University of Texas at Austin.

“Talking about mortality figures and large body counts, you see people’s eyes glaze over,” Apte says. “People care not just about whether you die — we all die — but also how much younger are you going to be when that happens.”

UNEQUAL IMPACTS  As the ambient concentration of fine particulate air pollution (PM2.5)  increases in a country, so does the loss in average life expectancy. But each population has its own baseline health level, so mortality impacts vary from country to country. This analysis is based on 2016 data.

Source:  J.S. Apte et al/Environmental Science & Technology Letters 2018; Credit: SN Staff

Even in high-income countries with relatively clean air, such as United States and Australia, the little bit of PM2.5 pollution that does exist costs those countries’ average citizen a few months of life.

Apte and his colleagues also calculate the potential benefit to each country of limiting ambient PM2.5levels to 10 micrograms per cubic meter of air, as recommended by the World Health Organization. Many high-income countries, including Canada, already meet this standard, but others, typically in the developing world, often have pollution levels many times higher.

By meeting the WHO standard, Egyptians, for example, could gain back about 1.3 years of life on average, while Chinese life expectancy would increase by an average .76 years, or a little over nine months.

But bringing down air pollution doesn’t fully restore all life expectancy lost as a result of the pollution, because there are still significant health risks below 10 micrograms per cubic meter.

How cleaning up the air can lengthen lives

LONGER LIVES  Reducing ambient fine particulate air pollution (PM2.5) levels to 10 micrograms per cubic meter could result in gains in life expectancy (shown per country). But that reduction in dirty air doesn’t reverse all pollution-related life expectancy losses, thanks to the significant health risks that still exist at the lowest pollution levels. Some countries that already meet the 10 µg/m3 mark are shown as having no gain.

Source:  J.S. Apte et al/Environmental Science & Technology Letters 2018; Credit: SN Staff

For India, which is among the worst polluted countries in the world, clearing the air to WHO standards would give a 60-year-old person a 20 percent better chance of surviving to 85, according to the authors’ calculations.

The scientists also compared how different risk factors, such PM2.5 pollution, smoking or cancer, shorten average life expectancy by region. In the case of South Asia, for example, PM2.5 air pollution had a bigger impact on mortality than all cancers combined.

The results show that improving air quality can increase life spans at a scale that’s as large or larger than some other common health priorities, including improving water sanitation or tackling breast or lung cancer. In high-income countries, that trend was reversed, with air pollution curbing life expectancy by less than half a year, while all forms of cancer shortened the average life by more than 3.5 years.

“That can really help people, or policy makers, decide where to spend their money,” says Kirk Smith, a global environmental health expert at the University of California, Berkeley, who was not involved in the study. “It’s another bit of analysis that shows air pollution is a major risk factor globally.”


JUGGLING RISKS  Fine particulate air pollution (PM2.5) is just one of today’s many common health risks, but in some places it can have more impact than other high-profile problems like lung cancer or poor water quality.

Source:  J.S. Apte et al/Environmental Science & Technology Letters 2018; Credit: SN Staff

Unlike other similar research, the new study puts air pollution mortality impacts in the context of how long people normally survive in a given country, rather than treating all countries and populations the same. So the results reflect the baseline level of health in any given country. For example, because Russia and Ukraine have older populations, the PM2.5-related mortality rates are higher than expected given those countries’ relatively low pollution levels.

A total of 42 countries, mostly in Africa and Asia, saw life expectancy decreased by at least a year due to the fine particulate matter. “A year is a long time, if you think about it for every person in a country,” Apte says. “And everybody benefits when the air is improved.”

Editor’s note: This story was updated August 23, 2018, to correct the life expectancy impact in India of air pollution.