Evaluation on the effect of regional joint control measures in changing photochemical transformation: A comprehensive study of the optimization scenario analysis

Abstract

<p><strong>Abstract.</strong> Heavy haze usually occurs in winter in eastern China. To control the severe air pollution during the season, comprehensive regional joint-control strategies were implemented throughout a campaign. To evaluate the effectiveness of these strategies and to provide some insight into strengthening the joint-control mechanism, the influence of control measures on levels of air pollution were estimated. To determine the influence of meteorological conditions, and the control measures on the air quality, in a comprehensive study, the 2nd World Internet Conference was held during December 16~18, 2015 in Jiaxing City, Zhejiang Province in the Yangtze River Delta (YRD) region. We first analyzed the air quality changes during four meteorological regimes; and then compared the air pollutant concentrations during days with stable meteorological conditions. Next, we did modeling scenarios to quantify the effects caused due to the air pollution control measures. We found that total emissions of SO<sub>2</sub>, NO<sub><i>x</i></sub>, PM<sub>2.5</sub> and VOCs in Jiaxing were reduced by 56 %, 58 %, 64 % and 80 %, respectively; while total emission reductions of SO<sub>2</sub>, NO<sub><i>x</i></sub>, PM<sub>2.5</sub> and VOCs over the YRD region are estimated to be 10 %, 9 %, 10 % and 11 %, respectively. Modelling results suggest that the regional controls (including Jiaxing and surrounding area) reduced PM2.5 levels in Jiaxing between 5.5 %–16.5 % (9.9 % on average), while local control measures contributed 4.5 %–14.4 %, with an average of 8.8 %. Our implemented optimization analysis compared with previous studies also reveal that local emission reductions play a key role in air quality improvement, although it shall be supplemented by regional linkage. In terms of regional joint control, to implement pollution channel control 48 hours before the event is of most benefit in getting similar results. Therefore, it is recommended that a synergistic emission reduction plan between adjacent areas with local pollution emission reductions as the core part should be established and strengthened, and emission reduction plans for different types of pollution through a stronger regional linkage should be reserved.</p>

Diurnal and temporal changes in air pollution during COVID-19 strict lockdown over different regions of India

“…The changes in pollutants level during the COVID-19 lockdown across India can partially or significantly be affected by the meteorological conditions during this period. However, changes in the air pollution due to the emission change can be studied by comparing the average pollutant concentrations under the same meteorological conditions ( Li et al., 2019 ; Cheng et al., 2017 ). We compare the MERRA-2 meteorological parameters during 2017–2019 with the 2020 during lockdown months (March–May).…”

Temporally-resolved sectoral and regional contributions to air pollution in Beijing: Informing short-term emission controls

“…However, PM 2.5 concentrations still peak at 253 µg m −3 and 175 µg m −3 during the episodes of 24 and 30 October, respectively, and these levels remain well above the national daily air quality standard. Recent independent modelling studies have highlighted the continued persistence of haze episodes in the region even after the implementation of clean air policies (Dang and Liao, 2019;Li et al, 2019). This emphasises that short-term emergency measures remain indispensable for avoiding the most severe haze episodes and our study provides a guiding framework for their formulation.…”