Asphalt is a significant source of air pollution in urban environments, according to a new study published in the journal Science Advances.
Extensive research about emissions from motor vehicles has increased our understanding of air pollution, however according to researchers at Yale University, numerous non-combustion-related sources are also important contributors to air pollution.
To assess the impact of such non-combustion sources, the researchers collected fresh asphalt, a material found in roads, roofs and driveways, and heated it to different temperatures.
They found that when asphalt is exposed to moderate solar radiation it results in a 300% increase in seconadry organic aerosols (SOA). SOA is a major contributor to particulate matter (PM2.5) an air pollutant which is known to have negative impacts on public health.
The researchers also found that asphalt emissions doubled when the temperature increased from 40C to 60C — levels the material often reaches in summer.
After some time, the researchers found that emissions at summer temperatures leveled out, but then persisted at a steady rate, suggesting that there are long-term, continued emissions from the asphalt in real-world conditions.
The researchers said that finding new ways to make roads more environmentally friendly is as important as doing the same for cars and trucks.
Peeyush Khare, a graduate student in Gentner’s lab and lead author of the study, added: ‘A main finding is that asphalt-related products emit substantial and diverse mixtures of organic compounds into the air, with a strong dependence on temperature and other environmental conditions.
‘That’s important from the perspective of air quality, especially in hot, sunny summertime conditions.’
In related news, earlier this year a ground-breaking study has suggested that particles released from vehicle tyres could also be a ‘significant’ source of microplastics in the world’s oceans.
The study is one of the first worldwide to identify tyre particles as a major and additional source of microplastics. Scientists have previously discovered microplastics, originating from microbeads in cosmetics and the degradation of larger items such as carrier bags and plastic bottles, in marine environments globally – from the deep seas to the Arctic.
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