What are VOCs? Its source and impact
What are VOCs? What aspects of VOCs come from our production and life? How does VOCs affect air quality? Why is it difficult to control VOCs? Where should we work? Let's hear how the national environmental protection urban environmental pollution prevention and control key points answer these questions.
Environmentalists everywhere have begun to pay attention to the issue of VOCs and ozone treatment in summer, and achieve "summer disease and winter treatment". National environmental protection focus on prevention and control of urban environmental particulate pollution.
What are VOCs?
According to the WHO definition, volatile organic compounds (VOCs) refer to various organic compounds with a boiling point of 50 ° C to 260 ° C at normal temperature. VOCs can be further divided into alkane, aromatic hydrocarbon, ester, aldehyde and others according to their chemical structure. More than 300 have been identified. The most common are benzene, toluene, xylene, styrene, trichloroethylene, chloroform, trichloroethane, diisocyanate (TDI), diisocyanate, and the like.
What aspects of VOCs come from our production and life?
VOCs, as a volatile organic compound, have a very wide range of sources in daily production and life.
First, industrial sources. Petrochemical, chemical, coal-fired, coking industries will emit more VOCs. VOCs are emitted from paint spraying, such as home decoration, car painting, etc.
Second, the source of life. Motor vehicles are a major source of VOCs, not only motor vehicle exhaust, but also the oil used by motor vehicles. Their volatilization in transportation, storage and gas stations is also a major source of VOCs. In addition, food, barbecue, biomass burning, etc. will also volatilize a large amount of organic matter.
Third, natural sources. Plants volatilize organic matter, especially in summer when vegetation conditions are better.
In general, VOCs emissions are the type of pollution with the most sources, and all aspects of our production and life will produce some VOCs emissions.
How does VOCs affect air quality?
First, because VOCs are a type of volatile organic compounds, including many types and many kinds of substances, they have reached tens of thousands. VOCs themselves include many substances that are harmful to the human body, such as polycyclic aromatic hydrocarbons.
Second, VOCs are the most important material basis in the photochemical reaction chain of the atmospheric environment. The participation of VOCs in photochemical reactions can lead to two effects. On the one hand, under the conditions of appropriate light and temperature in summer, VOCs participate in photochemical reactions under the initiation of nitrogen oxides, which will lead to an increase in ozone concentration.
Third, when VOCs participate in a series of photochemical reactions, they will change from a gaseous state to a solid state, producing secondary organic aerosols, which will become part of the particulate matter and increase PM2.5 pollution. In addition, due to the increase in ozone caused by VOCs, the atmospheric oxidization is enhanced, which will trigger a series of other reactions. For example, NO2 and SO2 in the atmosphere will generate nitrate and sulfate under the oxidation of ozone, which indirectly increases the concentration of PM2.5.