Particulate Matters: A breathtaking problem
You’ve seen it before in cities around the world: it’s a fine haze suspended over skyscrapers, shrouding our urban landscapes in dense clouds of orange smog, reducing visibility, and making the air we breathe feel murky and heavy. It comes from the smoke that billows out of smokestacks, construction projects, cars on our roads, and from wildfires that rage around the world. Ambient air pollution, formed of particulate matter (tiny particles measured in microns, which are 1/1000th the size of a millimetre), is one of the leading contributors to climate change. It also has a tremendous impact on human health.
What is PM2.5?
The most dangerous of these airborne particles is something called particulate matter 2.5 (PM2.5). Also known as fine particulate matter, it’sformed of microscopic particles and droplets in the air that are two and a half microns or less in width — 1/30th the width of a human hair and smaller. These minute particles can be produced by natural forces, such as ash and soot from volcanoes, sand from deserts, dust, and sea-spray. The vast majority, however, come from human activity, mostly from combustion, such as engine exhaust from cars, trucks, busses, construction equipment, and cruise ships, as well as the burning of wood and coal. Household cooking with solid fuels (such as wood, kerosene, and coal) over open fires or indoor stoves is another major contributor to increased levels of PM2.5.
Due to its incredibly small size, PM2.5 tends to remain suspended in the air longer than other airborne particles, such as PM10 (or coarse particulate matter — particles that are 10 microns in width or less), which tends to settle more quickly. While both PM10 and PM2.5 can penetrate deep inside our lungs, it’s PM2.5 that poses the gravest danger to our health. These particles are so small that our body has an even harder time filtering them out, allowing them to penetrate more deeply into our lungs. They’re even able to pierce the lung barrier and enter our cardiovascular system. According to the WHO (World Health Organization) even low concentrations of PM2.5 can have damaging impacts on our health; in fact, there is no safe level of PM2.5 exposure.
What is it doing to our health?
The short-term health effects of fine particulate matter range from eye, nose, throat and lung irritation, to coughing, sneezing, runny nose and shortness of breath. Exposure to fine particles can also affect lung function and worsen medical conditions such as asthma and heart disease.
The long-term impacts of PM2.5 on human health are numerous and far-reaching: from heart disease, stroke, and lung cancer, to COPD, pneumonia, type-2 diabetes, and adverse birth outcomes. According to The State of Global Airreport, long-term exposure to PM2.5 contributed to 4.14 million deaths in 2019. It ranks 6th behind high blood pressure, smoking, and high blood sugar among others, and is “the leading risk factor among all environmental and occupational risks.” Some studies have even begun to connect increased exposure to PM2.5 and nitrogen dioxide (another harmful air pollutant) with mental disorders, such as anxiety and depression. Others have shown that it may increase sleep apnea.
Researchers have also recently begun to draw links between higher concentrations of PM2.5 and increased mortality from COVID-19. In fact, one Harvard University study shows that even “a small increase in long-term exposure to PM2.5 leads to a large increase in the COVID-19 death rate.”
Where is it occuring?
The impact of ambient air pollution tends to be felt more broadly amongst the poorest in our societies, with 91% of premature deaths attributable to PM2.5 occuring in low- and middle-income countries. The highest concentrations of PM2.5 globally occur in Africa, Asia, and the Middle East, with India, Nepal, Niger, Qatar, and Nigeria making up the countries with the five highest levels of PM2.5 in 2019.
In North America, air pollution has decreased considerably over the last 40 years according to The State of Global Air Report. Even so, an estimated 100,000 Americans still die prematurely every year due to increased exposure to PM2.5, and over one third of the United States’ population lives in counties with unhealthy levels of air pollution. Despite the country’s overall gains in the past few decades, according to a report by the American Lung Association, air pollution is rising across much of the country. With wildfires increasing in severity on the West Coast, ambient air pollution is becoming a growing threat to the health of millions of Americans.
Where do we go from here?
So what can be done to reduce the impact of PM2.5 on our lives? In 2005, the WHO developed guidelines for limits of harmful air pollutants, such as PM2.5. In 2015, the WHO and its member states adopted a resolution and roadmap for an “enhanced global response to the adverse health effects of air pollution.” While some regions — notably Southeast Asia, East Asia, and Oceania — led by China, Vietnam, and Thailand have in recent years found ways to reduce levels of PM2.5, according to The State of Global Air report, “there has been little or no sustained progress in the most polluted regions.”
In the spring of 2020, due in part to stay-at-home orders around the world, society caught a glimpse of what a world free of pollution might look like; with images of blue skies over Delhi, and fish swimming in the canals of Veniceabounding online. As the clouds of smog have slowly returned, we’re left to wonder: what might it take to lift the shadow harmful air pollutants like PM2.5 have left hanging over our world?
