cleaner air

Solutions for cleaner air

July 4, 2025 By EarthWise Leave a Comment

Air pollution is a problem for most of the world’s cities. Many cities in India and China continue to face major public health crises due to their polluted air. American cities also don’t escape from polluted air. Californian cities still struggle with smog despite decades of effort to reduce it. But one major city that has waged a successful battle against air pollution is Paris, France.

Over the past 20 years, Paris has transformed its air by trading automobile roads for bike lanes, adding green spaces, and eliminating 50,000 parking spaces.

According to independent air quality tracking, levels of fine particulate matter in Paris have decreased 55% since 2005 and nitrogen dioxide levels have fallen 50%. A combination of regulations and public policies including steps to limit traffic and ban the most polluting vehicles have produced these results.

Despite pushback from various sources such as car owners’ associations, suburban commuters, and right-leaning politicians, Parisians have continued to pursue cleaner air policies. In April, Parisians voted to turn an additional 500 streets over to pedestrians. Last year, Paris sharply increased parking fees for SUVs, forcing drivers to pay three times more than they would for smaller cars.

Ambitious policymaking can directly improve health in large cities. As one former advisor to the city explains, the French capital has developed “an urban policy based on well-being.”

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Paris said au revoir to cars. Air pollution maps reveal a dramatic change.

Photo, posted June 3, 2018, courtesy of Francisco Anzola via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Importance Of City Trees | Earth Wise

January 28, 2022 By EarthWise Leave a Comment

It is well known that green spaces can improve the quality of life and create a better climate in cities. City trees and vegetation can help reduce urban heat island effects by shading buildings and roads, deflecting radiation from the sun, and releasing moisture into the atmosphere. City trees and green spaces have also been proven to increase property values, promote wildlife and plant diversity, reduce noise pollution, and improve human health. But how important are trees and vegetation for producing cleaner air in cities?

According to a new study led by researchers at the University of Gothenburg in Sweden, trees do contribute to cleaner air in cities, but the degree to which they do so varies greatly between different locations.

The research team measured air pollutants across seven urban settings in the city of Gothenburg, and compared them with pollutants on the leaves of deciduous trees. The researchers chose to focus on polycyclic aromatic hydrocarbons (PAHs), which are pollutants generated primarily during the incomplete combustion of organic materials, like coal, oil, and wood.

The results revealed that the pollutants in leaves did increase over time. The researchers were able to show a clear correlation between the level of air pollutants and the concentration of pollutants in leaves.

But at the same time, the researchers discovered that pollution levels varied greatly between measurement sites. For example, the levels of PAHs were seven times higher at the most polluted site (the city’s main bus station) than they were at a location on the periphery of the city.

The research team hopes its findings will be used to help guide the planning of future urban landscapes.

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Trees are important for cleaner air in cities

Photo, posted November 5, 2021, courtesy of Maria Eklind via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Shutting Down Pollution | Earth Wise

April 8, 2020 By EarthWise Leave a Comment

With much of the country shut down as the coronavirus forces people to stay at home, there has naturally been a drastic reduction of traffic on roads and highways. And with that decrease, there has been a dramatic reduction in pollution as well.

A satellite that detects emissions in the atmosphere linked to cars and trucks has observed huge declines in pollution in major metropolitan areas such as Los Angeles, Seattle, New York, Chicago, and Atlanta.

Los Angeles is infamous for its rush-hour traffic but that has pretty much ceased to exist. Similar changes can be seen in the San Francisco Bay Area, where nearly 7 million residents have been ordered to shelter in place. New York City is less dependent on car travel than in other metro areas, but the shutdown of office buildings, schools, and restaurants has nonetheless resulted in a substantial reduction of traffic on the streets of the city.

While this sudden decline in air pollution over U.S. cities has some near-term health benefits, those benefits are likely to be fairly minor in the big picture. When the coronavirus outbreak subsides and people are allowed to leave their homes and go back to their normal lives, air pollution will most certainly rebound to previous levels. In any event, studies have shown that long-term exposure to air pollution has a larger impact on public health than any transient events.

Having much cleaner air for a while is certainly a good thing, but this shutdown is not a sustainable way to reduce air pollution and the long-term effects of the coronavirus crisis will certainly not be positive.

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Traffic and Pollution Plummet as U.S. Cities Shut Down for Coronavirus

Photo, posted March 15, 2020, courtesy of Tom Collins via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Cleaner Air Saves Lives

September 25, 2019 By EarthWise Leave a Comment

A new study by Columbia University has concluded that lower air pollution levels saved an estimated 5,660 lives in New York State in 2012, compared to 2002 mortality levels.

The study looked at New York State levels of the specific type of pollution known as fine particulate matter, referred to as PM2.5. These microscopic particulates are a mixture of solid particles and liquid droplets that either come from burning fuel or are formed in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides from power plants, industries, and automobiles.

Long-term exposure to PM2.5 can lead to respiratory and cardiovascular problems.

The study looked at extensive amounts of data to analyze trends in PM2.5 levels across New York State. The data showed that PM2.5 levels dropped by 28 to 37% between 2002 and 2012. This was a result of continued progress in cleaner vehicles, the reduction of high sulfur-dioxide emitting coal-burning power plants, and other air pollution reduction programs. They calculated that this amount of reduction in PM2.5 reduced the air pollution mortality burden for New York State residents by 67% – from 8,410 premature deaths in 2002 to 2,750 deaths in 2012.

The study provides evidence that emission controls on air pollutants – which were initiated by the Clean Air Act of 1970 and later expanded in 1990 – have improved public health across New York State. According to the researchers, the study is a key step to documenting the health benefits from cleaner air.

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Air Pollution Cuts Are Saving Lives in New York State

Photo, posted June 29, 2014, courtesy of Paul Comstock via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.