People could add years to their lives in smog-plagued parts of the world if authorities could reduce particulate pollution – soot from cars and industry – to levels recommended by the World Health Organization (WHO), a new study reported.

No other large US city would benefit more than Fresno, California, which has soot concentrations at roughly twice the WHO guidelines.

Fresno residents would live a year longer if the region could meet the health organization’s recommended levels of exposure, according to the study by the US Energy Policy Institute at the University of Chicago.

The average resident in Los Angeles could add eights months of life. The average Sacramento resident would add nearly three.

In November 2018, millions of Californians were choking on high levels of particulates, due to smoke from raging wildfires.

The study doesn’t account for that, but instead, focuses on everyday levels of soot and fine particles, produced largely by vehicle exhaust and other burning of fossil fuels.

Worldwide, this exposure reduces average life expectancy by 1.8 years, comparable to the impact of smoking cigarettes, according to the study’s authors.

“While people can stop smoking and take steps to protect themselves from diseases, there is little they can individually do to protect themselves from the air they breathe,” said Michael Greenstone, an economics professor and director of the Energy Policy Institute.

The study demonstrates the health benefits worldwide of cleaning up the world’s most smog-plagued regions, where an estimated 5.5 billion people live.

But cutting pollution to WHO-recommended levels will not be easy. In Fresno, a 50% reduction in particulates would require much more aggressive emissions controls on cars, trucks, agricultural equipment and oil and gas operations – regulations resisted by industries.

At issue is what is known as “particulate matter 2.5”, or PM 2.5 – particles so fine they are just 3% the diameter of a human hair.

Unlike larger particles, this type of air pollution can lodge deep in a person’s respiratory system and contribute to lung disease, strokes, heart disease and other ailments.

In heavily populated countries such as India and China, auto emissions and smoke from coal and wood burning have created the highest concentrations of PM 2.5 on Earth.

According to the Energy Policy Institute, people in India would live 4.3 years longer on average, if that country could lower pollution to the WHO guidelines. People in China would live 2.9 years longer on average.

To estimate impacts on lifespan, the institute relied on a pair of peer-reviewed studies co-authored by Greenstone that quantify the relationship between particulate pollution and expected longevity.

The institute used that data to develop what it calls an “Air Quality Life Index”, so people can readily review the long-term health impacts of air pollution in different parts of the world.

Across the US, cities and states have a strong record of reducing soot levels in the air, the study notes.

Between 1970 and 2016, particulate pollution declined by 62% nationwide, largely because of cleaner vehicles and new requirements for scrubbers, and emissions controls on power plants and industries.

But not all areas have seen cleaner skies. Fresno’s ambient concentration of particulates – 20 micrograms per cubic litre – is effectively the same as it was in 1970, according to the institute.

The San Joaquin Valley Air Pollution Control District, the agency responsible for meeting federal air standards, blames the problem partly on the area’s bowl-like typography, which traps pollutants.

Environment and health advocates, by contrast, say the air district hasn’t been aggressive enough in regulating industries, farms and vehicle fleets.

In late 2012, the air district adopted a plan for meeting federal particulate standards by 2019. Recently, the air district’s board adopted an updated plan for coming into compliance, said executive director Samir Sheikh.

“Achieving these standards will be difficult and will require billions of dollars of new clean air investments,” he said, given the Valley’s geography, meteorology and volume of heavy duty trucks.

Since taking office, the Trump administration has a mixed record of addressing particulate pollution.

In October 2018, acting US Environmental Protection Agency (EPA) administrator Andrew Wheeler scrapped a scientific panel assigned to review air standards for particulates.

In November 2018, the EPA surprised environmentalists by announcing new pollution restrictions on heavy duty trucks. – McClatchy Washington Bureau/Tribune News Service