Long-term exposure to air pollution is like smoking a pack of cigarettes a day

The air you breathe could be doing as much harm to your lungs as smoking a pack of cigarettes a day, shortening your life and putting you at risk of chronic illnesses.

That’s one of the findings of a major study into the effects of air pollution on people’s health. Over the course of 18 years, researchers from the University of Washington, Columbia University and the University at Buffalo studied 7,000 people looking for signs of harm done by that most natural of things – breathing.

Over that time, 15,000 CT scans were analyzed, leading the research team to conclude that long-term exposure to air pollution was triggering rising rates of emphysema in the US.

It’s a life-threatening condition that involves damage to the alveoli – the tiny air sacs in your lungs. In an emphysema sufferer, the inner walls of the alveoli weaken and rupture, compromising the body’s capacity to get oxygen into the bloodstream.

No smoke without fire

Emphysema leads to difficulty breathing and can be a precursor to far more serious conditions, including collapsed lungs and heart problems. Traditionally, it has been associated with heavy-smokers or people who are routinely exposed to chemical fumes.

But pollutants like fine particulate matter, nitrogen oxide and black carbon are having a similar impact on the lungs of non-smokers.

“We were surprised to see how strong air pollution’s impact was on the progression of emphysema on lung scans,” says one of the study’s authors, Dr Joel Kaufman, UW professor of environmental and occupational health sciences and epidemiology in the School of Public Health. “[It’s] in the same league as the effects of cigarette smoking, which is by far the best-known cause of emphysema.”

While one of the largest ever investigations of its kind, the study is not the first to establish a link between air quality and health.

According to the Air Quality Life Index (AQLI), particulate air pollution can reduce life expectancy by an average of almost two years. Unsurprisingly, it’s worse in parts of the world where pollution is higher.

Sky-high levels of ground-level ozone

Earlier this year, a report from India’s Centre for Science and Environment concluded life expectancy for South Asians, including Indians, has reduced by around 2.6 years because of poor air quality.

Air pollution in India is a problem in the home as well as out on the street, and has overtaken smoking to become one of the top three causes of death.

The US-based study examined people living in six metropolitan areas: Winston-Salem in North Carolina; St Paul in Minnesota; New York City; Baltimore; Chicago; and Los Angeles.

Signs of emphysema were detected and measured from an analysis of CT scans that revealed the tell-tale holes in the alveoli. Additional monitoring was carried out via lung function tests that measured the speed and volume of air breathed in and out.

One of the chief causes of harm is the presence of ground-level ozone. This is created by a chemical reaction between oxides of nitrogen, sunlight and a broad catch-all category of pollutants called volatile organic compounds (VOC). Vehicle exhaust fumes, chlorofluorocarbons, solvents, adhesives, paint, formaldehyde, ceiling tiles, and even new furniture are all sources of VOCs.

On hot sunny days with little or no wind, ground-level ozone can soar to dangerously harmful levels. It is the main ingredient of smog, which is routinely pictured enveloping some of the world’s most populated cities.

And unlike stratospheric ozone, which occurs naturally in the upper atmosphere and forms a shield against the sun's ultraviolet rays, ground-level ozone is a health hazard.

“These findings matter since ground-level ozone levels are rising, and the amount of emphysema on CT scans predicts hospitalization and deaths due to chronic lung disease,” says Dr R Graham Barr, professor of medicine and epidemiology at Columbia University.

“As temperatures rise with climate change, ground-level ozone will continue to increase unless steps are taken to reduce this pollutant. But it’s not clear what level of air pollutants, if any, is safe for human health.”

There are few alternatives to breathing the air around you, so the challenge of addressing the air quality health burden lies with local and national governments.

Initiatives to limit vehicle use in and access to some urban areas is a common approach across Europe. Recently, a row broke out in New York over a proposal to ban most cars from some of the busiest parts of Manhattan.

Other initiatives to counter the effects of pollution in cities include planting more trees, encouraging more people to use public transport, and investments in cycling infrastructure – a move that could potentially improve air quality and people’s health at the same time.