Concerned about the effects of urban air pollution? If the air you’re breathing is an issue you’re mindful of, then “particulate matter” is a phrase to know. It might sound like scientific jargon at first blush, but in simplest terms, it refers to pollutants that take the form of solid, microscopic particles (and which are dangerous to human health).
What Are Particulate Emissions?
According to the World Health Organization, the major components of particulate matter, or PM, are sulfates, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. That might not sound particularly noteworthy, but consider that the WHO also detects a correlation between the presence of PM and adverse health effects: “There is a close, quantitative relationship between exposure to high concentrations of small particulates (PM10 and PM2.5) and increased mortality or morbidity, both daily and over time.” The organisation also finds a connection between PM exposure and chronic respiratory and cardiovascular diseases, as well as several forms of cancer.
Why Are Particulate Emissions Harmful?
Particulate emissions are clearly a serious health issue, so it helps to understand more about what makes them so toxic to humans. PM is divided into several major categories, based on the size of the particles in question: PM10 and PM2.5, or particles that measure less than 10 or 2.5 micrometres, respectively, plus the “ultrafine” particles that measure less than PM0.1. Whatever the size, PM is invisible to the naked eye, and so small that it’s easily dwarfed by the width of a strand of hair or a single grain of sand.
And that’s exactly what makes it so worrisome: these particles are minute enough that they can be easily breathed in and stored in the body. Larger PM10 particles are deposited primarily in the nose and throat, smaller PM2.5 particles reach the bronchial tubes, and ultrafine particles can even reach the interior of the lungs and enter the bloodstream.
There, they do the real damage. These particles can increase blood clotting, heighten the risk of stroke and heart attack, and can be carried to other organs, including the brain and the heart. Other studies have found that particles can lodge inside arteries and otherwise remain in the body for long stretches of time; there are also potential connections between PM and premature births, delayed childhood development, Alzheimer’s, asthma and bronchitis, and other severe conditions.
Simply put, the more PM detected, the greater the risk to human life. While there are annual caps in place for the presence of PM2.5 and PM10, there are no regulations for the finest particles, even though they are likely the most harmful.
Where Does PM Come From?
There are myriad sources of particulate emissions, some of them totally natural—volcanic eruptions and forest fires, for instance. Particles like dust, pollen, and soot all count, too.
Surprisingly, the consumer sector is now receiving more attention than ever as a major source of air pollution. Researchers have found that volatile organic compounds (VOCs) abound in common household cleaners, personal hygiene products, and even perfumes; in the air, they react with other chemicals to produce PM2.5 and ozone. Another surprising culprit are those cosy, wood-burning fireplaces that are a coveted piece of décor in urban apartments. They may look attractive (and the smell of wood smoke on a crisp winter’s day may appeal), but some estimates suggest that they’re responsible for up to a third of London’s particulate pollution.
Domestic sources aside, transportation is still one of PM’s greatest causes. Busy roadways are where heavy concentrations of PM are found, and its primary sources include diesel engine exhaust fumes, direct-injection petrol engines, and construction equipment.
How Can Cities Cut Back on PM?
The good news is that cities have an array of options available to them for cutting down PM—and many are already in place and having positive effects. Potential strategies, especially where vehicular emissions are concerned, include everything from introducing congestion charges, lowering speed limits, and adding more monitoring locations for fine particular matter; all are relatively simple fixes.
The WHO also offers up an in-depth list of recommendations, including the transit-focussed (prioritising mass transit, promoting walking and cycling networks, and shifting to low-emissions vehicles and clean modes of power generation) as well as more complex questions of urban planning that should guide cities into the future (improving energy-efficiency in buildings, installing rooftop solar panels, long-term waste reduction and recycling programmes, and beyond).
This is also an arena where consumers have the power and potential to remake their cities for the better. By cutting down on wood-burning fires at home, seeking low-emissions ways to commute, cleaning with all-natural products, and refraining from using aerosol deodorants and perfumes, it’s possible to make an impact with just a few simple lifestyle swaps.