BEIJING, Oct. 29 (Xinhuanet)-Liu Youbin, spokesman of the Ministry of Ecology and Environment, said on the 29th that since 2015, ozone monitoring has been carried out at 1,436 points in 337 cities across the country. The data shows that although ozone pollution in China has increased, it is mainly light pollution, and it is generally in a state of prevention and control.
On the morning of the 29th, the Ministry of Ecology and Environment held a regular press conference, and Liu Youbin, spokesman of the Ministry of Ecology and Environment, reported the recent progress of key work.
Liu Youbin introduced that not long ago, the Ministry of Ecology and Environment announced the national air quality in September and January-September, and some areas experienced some fluctuations. The Ministry of Ecology and Environment organized experts to carefully analyze these situations for the following reasons:
First of all, due to the higher temperature than normal, the national O3 concentration increased year-on-year, and the proportion of excellent days decreased year-on-year.. In September 2019, the national average temperature was 17.7 degrees, which was 1.1 degrees higher than normal. The average temperatures in Beijing, Tianjin, Jilin, Inner Mongolia, Hubei and other provinces and cities were the highest or second highest level in the same period since 1961. Under the influence of high temperature and strong light, the concentration of O3 increased obviously during the day, which led to a decrease in the proportion of excellent days.
Preliminary analysis shows that in September 2019, the number of days in which the primary pollutant was O3(8 hours) in 337 cities at prefecture level and above accounted for more than 95% of the polluted days and about 40% of the 23 heavily polluted days, and the primary pollutant in other heavily polluted days was PM10, indicating that the average daily air quality in September was mainly affected by O3 concentration. The average O3 concentration in 337 cities at prefecture level and above was 157 μ g/m3, up by 23.6% year-on-year, and the proportion of excellent days decreased by 14.7 percentage points year-on-year.
Tropospheric (near-surface) ozone is a typical secondary air pollutant, which is rarely emitted by human beings. The main source of ground ozone is the photochemical reaction of NOx and VOCs under the action of heat and sunlight. When the precursors of NOx and VOCs are high, ozone pollution is easy to occur in summer and autumn due to high temperature and strong solar radiation. China’s standard stipulates that the maximum daily average concentration of ozone for 8 hours is 160 μ g/m3, which is basically equivalent to that of developed countries. Since 2015, ozone monitoring has been carried out at 1436 locations in 337 cities across the country. The data show that although ozone pollution in China has increased, it is mainly mild pollution, and it is generally in a state of prevention and control.
Secondly, less precipitation and unfavorable meteorological conditions lead to an increase in particulate matter concentration.In September 2019, the static stability index of the Beijing-Tianjin-Hebei region increased by about 50% year-on-year, of which the static stability index of Beijing increased by about 40% year-on-year, and the atmospheric diffusion capacity decreased significantly. Especially in late September, 2019, Beijing-Tianjin-Hebei and surrounding areas experienced static, high humidity and inversion weather lasting for more than one week, which led to the continuous accumulation and transformation of pollutants.
According to Liu Youbin, in view of the above situation, the Ministry of Ecology and Environment will promote the coordinated emission reduction of multi-pollutants with the coordinated control of PM2.5 and ozone, focusing on NOx and VOCs, and actively promote the optimization and adjustment of industry, energy, transportation and land use structure.
Liu Youbin Qiu said that winter has come, the temperature has dropped, and the O3 pollution level has dropped. Especially after entering the heating season, the emission intensity of various pollutants will further increase and the meteorological conditions will deteriorate, and PM2.5 will become the primary pollutant that determines the ambient air quality. The Ministry of Ecology and Environment, together with relevant departments and localities, will take measures such as differentiated and graded management and control of key industries to actively deal with heavily polluted weather to offset the impact of increased heating emissions and unfavorable meteorological conditions.
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