[Assessment of Emission Reduction Effect of Major Air Pollution Control Measures on PM 2.5 Concentrations During 13th Five-Year Period in Tianjin].

The emission reduction effect of major air pollution control measures on PM _2.5 concentrations was assessed using air quality simulations based on the calculation data of emission reductions from different air pollution control measures and the high spatiotemporal resolution online monitoring data of PM _2.5 during the 13th Five-Year Period in Tianjin. The results showed that the total emission reductions of SO ₂ , NO _x , VOCs, and PM _2.5 from 2015 to 2020 were 4.77×10 ⁴ , 6.20×10 ⁴ , 5.37×10 ⁴ , and 3.53×10 ⁴ t, respectively. SO ₂ emission reduction was mainly due to the prevention of process pollution, loose coal combustion, and thermal power. NO _x emission reduction was mainly due to the prevention of process pollution, thermal power, and steel industry. VOCs emission reduction was mainly due to prevention of process pollution. PM _2.5 emission reduction was mainly due to the prevention of process pollution, loose coal combustion, and the steel industry. The concentrations, pollution days, and heavy pollution days of PM _2.5 decreased significantly from 2015 to 2020 by 31.4%, 51.2%, and 60.0% compared to those in 2015, respectively. The concentrations and pollution days of PM _2.5 decreased slowly in the later stage (from 2018 to 2020)as compared with those in the early stage (from 2015 to 2017), and the days of heavy pollution remained for approximately 10 days. The results of air quality simulations showed that meteorological conditions contributed one-third to the reduction in PM _2.5 concentrations, and the emission reductions of major air pollution control measures contributed two-thirds to the reduction in PM _2.5 concentrations. For all air pollution control measures from 2015 to 2020, PM _2.5 concentrations were reduced by the prevention of process pollution, loose coal combustion, the steel industry, and thermal power by 2.66, 2.18, 1.70, and 0.51 μg·m ^-3 , respectively, accounting for 18.3%, 15.0%, 11.7%, and 3.5% of PM _2.5 concentration reductions. In order to promote the continuous improvement in PM _2.5 concentrations during the 14th Five-Year Plan period, under the total coal consumption control and the goal of "peaking carbon dioxide emissions and achieving carbon neutrality," Tianjin should continue to optimize and adjust the coal structure and further promote the coal consumption to the power industry with an advanced pollution control level. At the same time, it is necessary to further improve the emission performance of industrial sources in the whole process, taking environmental capacity as the constraint; design the technical route for industrial optimization, adjustment, transformation, and upgrading; and optimize the allocation of environmental capacity resources. Additionally, the orderly development model for key industries with limited environmental capacity should be proposed, and clean upgrading, transformation, and green development should be guided for enterprises.