An outdoor exerciser_ here’s what your lungs probably look like. – the washington post

By Caroline Wellbery March 28

When a pathologist at Georgetown University’s medical school cut into the lungs of a cadaver during an autopsy and revealed blackened tissue, one of my medical students assumed that smoking must have contributed to the person’s death. No, the pathologist said; he’d seen such carbon-pocked lungs hundreds of times. “That’s what all our lungs look like.”

The truth is that air pollution damages our lungs not only in places such as Beijing and New Delhi, where smoggy air and white masks have become a way of life for many. U. S. air may not look as gritty, but Americans living in high-density areas, even suburban ones, also face plenty of negative health consequences from pollution, including heart attacks and asthma.

A recent study found that 5.5 million people worldwide die prematurely every year because of dirty air, much of it from power plants and, especially in the United States, automobiles. Particulate and gaseous pollutants in the air have been blamed for as many as 10 percent of deaths in Los Angeles.

So what are we breathing that’s causing such damage?

Our air has two forms of pollution; one of them includes gases such as ozone, carbon monoxide, nitrogen dioxide and sulfur dioxide. Of these, ground-level ozone is a major respiratory culprit, created when sunlight interacts with exhausts from vehicles and other machinery. Ozone is a potent lung irritant and is partly responsible for the rise in rhinitis and asthma worldwide. The warmer the air, the greater the reaction. Recent studies have determined ozone to be the pollutant most closely associated with increased mortality.

The other form of pollution is tiny particulate matter — from automobile fumes, power plants and smoke from chimneys and forest fires — that lodges in the lungs and pretty much stays there.

Particulates are what blacken our lungs over time, but both ozone and particulates cause breathing problems and shorten life spans by making lungs sensitive to allergic substances, causing inflammation and reducing lung function. These changes trigger asthma attacks, worsen illnesses such as chronic obstructive pulmonary disease, or COPD, and are even linked to the development of lung cancer.

The smaller particulates are, the more dangerous their effect. One common particulate goes by the scientific name PM 2.5. Its tiny dimensions — it’s often described as being one-thirtieth as wide as a hair — allow it to enter the deepest recesses of the lungs. We take in millions of them with each breath. PM 2.5s are made up of sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. While some of these components occur naturally in the air, others come from burning coal and wood, fuel combustion and other human activities. No one knows exactly which of these man-made ingredients are most toxic to the lungs. What is clear is that the particles’ minuscule size allow them to stay in the air for long periods, travel great distances and, worst of all, evade the body’s defenses. They pass right by the small hairs in our nose and bronchial tree, which are better suited for trapping larger particles.

The Environmental Protection Agency and the American Lung Association are among several organizations with websites that provide information on ozone and particulates in many U. S. cities.

For 2014, the District received an “F” grade from the ALA — eighth-worst in the country — for ozone levels, calculated from hourly readings at monitoring sites over a three-year period. (Recent studies have determined ozone to be the pollutant most closely associated with increased mortality.) The District received a “D” for particulates. Los Angeles topped the list for worst ozone pollution and the area around Fresno, Calif., ranked highest for particulates.

Some U. S. cities fared better: Anchorage had the lowest level of ozone pollution in the country, whereas Prescott, Ariz., had the lowest levels of particulates. The cleanest city in the world was Calgary, Alberta. Meanwhile, clean-air tourists would do well to steer away from Linfen, China, the world’s most polluted city.

Whose health is most at risk? People older than 65, who tend to have less efficient lungs and immune systems, and children, who spend more time outdoors and have higher respiratory rates than adults, are particularly sensitive to ozone, as is anyone with asthma, COPD, cardiovascular disease or diabetes. People of all ages living near high-traffic roads and other sources of pollution, such as smokestacks, have been found to have more health issues, including cardiovascular risk and lung disease, than other people.

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What about athletes in urban areas who inhale automobile exhaust while running and cycling outdoors? Exercisers inhale particles through the mouth, bypassing the nasal filtration system, and often draw the inflammatory particles deep into the lungs. Exercise, however, is definitely good for your cardiovascular system and probably offsets some of the cardiovascular health risks of living in a polluted environment.

What should urban dwellers do?

If you’re not going to move to Anchorage or Canada, you can still protect yourself and limit your contribution to air pollution. The ALA suggests driving less and reducing the use of gas-powered tools, air conditioning and wood-burning fireplaces. It also recommends staying indoors on high-pollution days and avoiding exercise near zones of heavy traffic. Short of using cans of imported air from Canada, as we now hear is all the rage in China, some people have suggested using the face masks many in Beijing now wear as a barrier to toxic air.

Such masks, which were popularized in Japan after the 1918 flu, have continued to be used worldwide in surgical settings and have served as a public health measure to protect against airborne infections.

Some masks — labeled N95 and N99 — provide protection against most of the worrisome airborne particles. However, they can be uncomfortable to wear — they’re thicker and less flexible than a surgical mask — and reduce airflow, creating a sensation of difficulty breathing.

I’ve tried an N95 respirator mask for running and an N95 plain face mask for cycling. In both cases the exertion made breathing more difficult. And because the masks make you look like a giant irradiated bug, I drew incredulous stares when I wore one biking down a congested part of River Road in Bethesda.

Some companies have addressed this problem by attempting to recast masks as hip urban fashion statements.

Others have created personal environmental monitors, which keep track of air quality and communicate with a smartphone to help you figure out when to don a mask.

These masks and apps may help give a sense of control, but they’re not long-term solutions. That’s why some organizations are focusing on the respiratory health of future generations. We can’t get rid of those black spots dotting our lungs; our best bet is to keep young lungs pink in the first place.

Wellbery is a family physician and medical educator at the Georgetown University School of Medicine.