When ozone (O3) replaces PM2.5 as the "chief culprit" of air pollution in summer, nitrogen oxides (NOx) have attracted the attention of environmental protection experts as one of the important substances to produce ozone. What exactly is the effect of nitrogen oxides and how to reduce ozone pollution by controlling nitrogen oxides? Recently, the Chengdu Environmental Protection Bureau launched a popular science column, detailed answers to these questions.
Q: are nitrogen oxides important for ozone generation?
Answer: in the sunlight, nitrogen oxides and volatile organic compounds through a series of photochemical reaction of ozone, formaldehyde, acetaldehyde and other two pollutants; ozone is one of the factors leading to enhanced atmospheric oxidation, ozone with high concentration and long time to further develop the formation of photochemical smog, causing harm to the environment and human health. The main force causing ozone pollution is "anthropogenic sources": emissions of coal, motor vehicle exhaust, petrochemical and other pollutants, such as nitrogen oxides. In other words, the depth of nitrogen oxide participates in the two photochemical reactions in the atmosphere, which is one of the main causes of ozone generation.
Q: how can we control nitrogen oxides to reduce ozone pollution?
Answer: to control ozone pollution, from the root, it is necessary to control nitrogen oxides and volatile organic compounds (VOCs) emissions. This is similar to the governance of PM2.5, in the final analysis is to control emissions. Unfortunately, at present, China's annual emissions of nitrogen oxides account for 16.4% of the world's total emissions, and there are still 50% of industrialized areas in the country increasing emissions of nitrogen oxides. Especially for densely populated urban areas, motor vehicle exhaust is the chief culprit of photochemical pollution".
So, should strictly comply with emission standards, improve the quality of oil, the use of clean fuel, improve the working condition of vehicle engine installation, vehicle exhaust purification device, which is an important method for prevention of photochemical pollution. At the same time, it is necessary to strengthen the management of the exhaust emission of the factory, reduce the emission limit, establish a monitoring station, and constantly monitor the situation of photochemical pollution.
In short, although less nitrogen oxides were filed, but because of their participation in the photochemical reactions of ozone formation is harmful to human health, therefore, should pay attention to the Environmental Protection Bureau of daily air quality released, the ozone pollution should reduce outdoor activities.