Asphalt roads can pollute more than cars, says study


A study by researchers at Yale University, conducted by environmental engineer Drew Gentner, found that asphalt can be as – or even more – polluting as fossil fuel cars. This was the first study of its kind to consider asphalt an air pollutant.

Perhaps, even worse than the cars themselves

As gasoline and diesel vehicles have evolved, they have started to emit less greenhouse gases. On the other hand, asphalt is made of crude oil, or similar substances, and contains the types of semi-volatile organic compounds that lead to some types of air pollution.

In the study, the researchers heated two types of fresh road asphalt, as well as shingles made of asphalt and liquid asphalt used on roofs. The material released a greater amount of semi-volatile organic compounds when it was heated to 140 ºC, which is the road paving temperature. Emissions were falling as the material cooled, but it still continued to release many particles, and continuously, at 60 ºC, typical temperature for asphalt in Los Angeles during the summer, during the three-day experiment. This characteristic indicates that asphalt can be a source of long-term pollution, according to scientists.

The team also found that sunlight, even at moderate levels, can cause emissions to increase by 300%, even if the material is not heated.

With these data in hand, the researchers estimated that new asphalt roads, along with roofs from Southern California, made from this material, are responsible for releasing 1,000 to 2,500 tons of polluting particles into the air annually.

Meanwhile, in the same period, cars powered by fossil fuels “only” release 900 to 1,400 tons of polluting particles.

Although the study has not been as comprehensive, environmental experts already consider it important for the industry to take measures to minimize the negative impact of asphalt in relation to air quality.


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