Paved surfaces and roofs make up 45% of the surfaces of urban areas. Asphalt is a major component of these surfaces, yet little has been studied about how toxic chemicals that make up the material may be emitted in our everyday lives.
In their recent paper in Science Advances, graduate student Peeyush Khare and Professor Drew Gentner study how various toxic gases are emitted from asphalt. Some of these toxic gases are known as secondary organic aerosols, which means that they emit from reactions occurring within a material. These secondary organic aerosols are a major component of PM2.5 materials, particulate matter that is smaller than 2.5 μm or 30 times thinner than human hair. PM2.5 materials pose major human health risks, because they are so small that they can get deep into lungs, airways, and even the bloodstream. To study such emissions, the researchers placed asphalt samples into a chamber and subjected them to different levels of environmental stresses, such as sunlight or temperature. They then used advanced techniques to characterize the types of chemicals released. According to their findings, asphalt releases double the amount of toxic pollutants when its surface temperature increases from 40°C to 60°C, which is often reached in the summertime, and nearly 300% more when exposed to sunlight as compared to no sun. These increased emissions were observed for asphalt road, roofing, and sealing materials. In total, the asphalt-related sources produce more organic aerosol than gas and diesel on-road vehicles combined.
Asphalt is an important building material, but is often overlooked in terms of the emissions it produces, especially compared to other more standard sources of emissions such as vehicles. Khare and Gentner’s work emphasizes that asphalt-related emissions are an important factor to study and regulate, especially as more and more urban areas are developed and paved. While the emissions behaviors of asphalt are dependent on environmental conditions, the higher emissions resulting from hot and sunny days require that we seriously consider asphalt as a source of pollutants.
Managing Correspondent: Eesha Khare
Press Article: https://phys.org/news/2020-09-asphalt-air-pollution-hot-sunny.html
Original Article: Asphalt-related emissions are a major missing nontraditional source of secondary organic aerosol precursors
Image: https://www.needpix.com/photo/909090/paving-workers-machines-asphalt-road-work-asphalting
Being a civil engineering, i have seen that the trend is rapidly changing. now the steel structures are being preferred. the use of concrete is getting subsided. the world is becoming aware of the hazardous product.
I think in next 25 years the pattern of construction might change and new product may emerge replacing to old technology.
there was a select club of engineers that has a very interesting activity whilch seems to be harmless wilch consisted in build rockets to fire to conquer the top layer of the atmosphere so every day they have higher and higher send their artifacts with sucess well it seems to as human progress but what is really happend? the space race is it free from ballasts? see we have degrade our planet with the goal other planets to conquer but now we haven´t neither other planets nor our own because we have life conditions degraded where? on the earth sea and atmosphere our planet is a plastics pit or asphalt jungle our air and wáter become useless our children grow as slackers and sedentary puppets inventors are blocked initiatives are cheated and all degenerate into a magma of inepts incompetents of overeaters anonimus
the first liberation of polluting element has to be in or own entourage here are a high poison called criminal mentality wilch consists in degrade the life others but not the own so these individuals have to be eradicate off from our society because they arm our way of life with many forms since 1780 and never has thought about their behabe they haven´t any kind of empathy to the rest of humanity and today are in the top Jobs where politics are implemented or dismantled according to their own interests so what kind of personality define these elements? they are in all of politic or social events as traitors and Works with ful protection of establishment to cover their crimes after through kill fabrics millions of people has been killed and all massakers are forgotten and the killers are perfect in system reintegrates for instance with paper clips