If you think the air where you live is relatively unpolluted, you’re almost certainly wrong: A new study found that 99.999 percent of the global population is exposed to air with unhealthy levels of tiny particulate matter every year. The research, from scientists at Monash University in Melbourne, Australia, got even more specific: It turns out that most days, you are also exposed to high levels of a pollutant called PM 2.5, which can travel deep into the lungs and bloodstream.
Their study was published on March 6 in The Lancet Planetary Health, and is the most high-resolution global estimate of PM 2.5 concentration to date. Using daily concentrations of PM 2.5 recorded by thousands of government air quality monitoring stations around the world, researchers trained a machine-learning algorithm to produce daily estimates for each country and the entire globe from 2000 to 2019. They compared average concentrations to the World Health Organization’s safety recommendations for the pollutant, set in 2021 to an average of 15 μg/m3 daily, or 5 μg/m3 annually.
PM 2.5 is mostly made up of sulfates, nitrates, ammonia, sodium chloride, black carbon, mineral dust, and water, according to the WHO, which is already not a pleasant-sounding combination. But the real damage is done when people breathe in the noxious mix: The tiny particles can irritate the throat and travel into the lungs, raising the risk of respiratory infections. Even low levels of PM 2.5 can cause inflammation and reduce lung function in otherwise healthy, young people. Exposure to the particulate pollution increases the rate of hospital admissions for heart attacks and strokes, and death.
Despite efforts to reduce air pollution in the past two decades, the study found that not much had changed for air quality at a global level. While PM 2.5 concentrations decreased in Europe, some parts of North America, and some regions of Africa, the pollutant’s concentration rose in other parts of Africa, most of Asia, Oceania, and Latin America. Only 0.18 percent of the global land area and 0.001 percent of the global population fell within the WHO’s annual guideline PM 2.5 limit of 5 μg/m3.
Though a startlingly few places in the world are shielded from the harmful effects of air pollution, people who live in developing countries or are poor or otherwise marginalized face even worse exposures. Countries in the Global South generally have weaker air quality regulations and older machines and cars that emit more pollution than state-of-the-art technology.
But even in developed nations, people in racial or ethnic minorities or who are in lower socioeconomic positions are likely to live near major sources of pollution. Pollutants like PM 2.5 have been found to have dose-response relationships to health problems including death, meaning the more you’re exposed to, the worse you’ll be affected.
Between 2000 and 2019, China led all countries in highest PM 2.5 concentration when weighed by the population affected by this pollution. But Niger, Pakistan, and Singapore led the world in the number of days residents were exposed to PM 2.5 levels above the WHO recommendations in 2000, 2010, and 2019, respectively. Each nation had fewer than five days of PM 2.5 concentration below the recommended limits.
This study adds to overwhelming evidence that efforts to reduce air pollution are absolutely too little, too late. Millions of people die each year from health conditions that are directly attributable to poor air quality, and “solutions”—like a set of air-purifying headphones that will set you back nearly $1,000—are downright offensive in their elitism. Until the world’s biggest air polluters decide to reduce their toxic footprints, the global population will bear the brunt of their effects.