According to a new study, in a hot day asphalt road, and roof coverings can put out more secondary organic aerosol (SOA) pollutants than the cars on the road.
Clearly, the change in weather is attracting more and more threat every day. These SOAs emitted by hot asphalt often go unreported when it comes to urban area pollutants. Chemical and environmental engineer Peeyush Khare from Yale University said,
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.
With the help of new technologies, the emissions from motor vehicles continue to go down. Now it becomes more important to track down and remove secondary pollutants like SOAs, which have lesser, but still significant negative effects on public health. The researchers behind the study are warning that we need to consider these pollutants while calculating air quality in urban areas.
The researchers experimented with asphalt monitored inside a tube furnace and heated up to a range of temperatures between 40 degrees Celsius and 200 degrees Celsius to determine SOA levels in hot conditions. SOA emissions doubled as the temperature climbed from 40C to 60C, and continued to rise as the temperature did – by about 70 percent for every 20C increase from 60C to 140C. Environmental engineer Drew Gentner from Yale University said,
To explain these observations, we calculated the expected rate of steady emissions and it showed that the rate of continued emissions was determined by the time it takes for compounds to diffuse through the highly viscous asphalt mixture.
Another study released earlier this year highlighted how the binder mix that holds asphalt together can react with sun and rain to leak toxic, carcinogenic polycyclic aromatic hydrocarbons (PAHs). The cities with a good amount of sunshine throughout the year, are right now the subject of interest for environmental researchers.