In the summer on the streets of many cities a newasphalt - probably everyone knows its fresh smell? Some people even like this peculiar aroma, but many do not even suspect that it can be dangerous to health. Recently, scientists from the United States and Germany decided to find out exactly what substances and in what quantity the road surface releases into the air. It turned out that every day, leaving the house, we inhale a huge variety of harmful substances that settle in our body and harm our health. In some regions of our planet, asphalt pollutes the environment as badly as cars with internal combustion engines. Within the framework of this material, I propose to understand what substances are contained in the "smell of asphalt", how they affect our health and how you can reduce the negative impact of the road surface.
The results of scientific work carried outby American and German scientists, were published in the scientific journal Science Advances. To determine what substances the asphalt releases, the researchers conducted a fairly simple scientific experiment. They took several samples of asphalt, heated them to high temperatures and studied the substances they released into the air using special sensors. It is important to note that they first heated the asphalt by placing it in a hot air environment. Then they heated the material, simulating exposure to direct sunlight.
What is PM2.5?
As it turned out, under the influence of hightemperatures, asphalt releases a cocktail of various substances into the air. About 85% of these are volatile particles less than 2.5 micrometers in size. In the scientific community, they are known as PM2.5 particles and their concentration is considered one of the mainair pollution indicators. Unlike larger objects, these particles are easier to enter the body and therefore pose the greatest threat. By themselves, they represent the smallest particles of heavy metals and soot, which absorbs many toxic substances.
See also: Where is the cleanest air on Earth?
Particles PM2.5 are found almost everywhere, even in the forest, but in cities there are most of them. Due to their small size, they easily overcome the defense systems of the human body such as the nasal cavity, upper respiratory tract and bronchi. Along with the inhaled air, microscopic particles enter the alveoli, which are bubbles for gas exchange between the lungs and the circulatory system. Since harmful substances can enter not only the lungs, but also the blood, substances released by asphalt can cause diseases not only of the respiratory system, but also of the cardiovascular system.
Emission of harmful substances to a greater extentprovoked not by hot air, but by exposure to direct sunlight. A laboratory experiment has shown that emissions can triple in hot weather. From this, it turns out that in regularly warm cities like Los Angeles, asphalt pollutes the air in much the same way as cars. The most harmful of all is fresh asphalt, just the one that emits a familiar smell to many. After some time, the concentration of harmful substances becomes less, but they do not completely evaporate even after years. It turns out that the asphalt laid in your yard a few years ago also regularly harms your health.
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The composition of asphalt includes sand, different types of graveland gravel, as well as bitumen - a product very similar in properties to resin. Depending on the manufacturer, the components may vary, except for bitumen, which is the link for all other components. Researchers believe that the harmful effects of asphalt can be eliminated if a new formulation is developed that does not include conventionally toxic components. At the moment, a safe asphalt composition does not exist, because for a long time researchers wanted to make an "indestructible" road surface. You can read about one of these projects in this article.