Coal-fired power plants (CPPs) dominate China's energy supply systems. Over the past two decades, the explosive growth of CPPs has led to negative air quality and health impacts in China, and a series of control policies have been implemented to alleviate those impacts. In this work, by combining a CPPs emission database over China (CPED), a regional chemical transport model (WRF-CMAQ), and the integrated exposure-response model, we summarized historical and ongoing emission control policies on CPPs over China, investigated the air quality and health impacts of China's CPPs during 2005-2020, and quantified the benefits of each policy. We found that despite the 97.4% growth of coal-fired power generation during 2005-2015, PM 2.5 exposures caused by emissions from China's CPPs decreased from 9.0 μg m −3 in 2005 to 3.6 μg m −3 in 2015. The active emission control policies have decreased CPPs-induced PM 2.5 exposures by 10.0 μg m −3 during 2005-2015. We estimated that upgrading end-of-pipe control facilities and early retirement of small and low-efficiency units could respectively reduce PM 2.5 exposures by 7.9 and 2.1 μg m −3 during 2005-2015 and avoid 111 900 and 31 400 annual premature deaths. Since 2015, China's government has further required all CPPs to comply with the so-called 'ultra-low emission standards' before 2020 as a major component of China's clean air actions. If the policy is fully deployed, CPPs-induced PM 2.5 exposures could further decrease by 2.5 μg m −3 and avoid 43 500 premature deaths annually. Our study confirms the effectiveness of tailored control policies for China's CPPs and reveals that those policies have played important roles in air quality improvement in China.

Abstract. The first wintertime in-situ measurements of hydroxyl (OH), hydroperoxy (HO 2 ) and organic peroxy (RO 2 ) 15 radicals (RO x =OH+HO 2 +RO 2 ) in combination with observations of total reactivity of OH radicals, k OH in Beijing are presented. The field campaign "Beijing winter finE particle STudy -Oxidation, Nucleation and light Extinctions" (BEST-ONE) was conducted at the suburban site Huairou near Beijing from January to March 2016. It aimed to understand oxidative capacity during wintertime and to elucidate the secondary pollutants formation mechanism in the North China Plain (NCP). OH radical concentrations at noontime ranged from 2.4×10 6 cm -3 in severely polluted 20 air (k OH ~ 27 s -1 ) to 3.6×10 6 cm -3 in relatively clean air (k OH ~ 5 s -1). These values are nearly two-fold larger than OH concentrations observed in previous winter campaign in Birmingham, Tokyo, and New York City. During this campaign, the total primary production rate of RO x radicals was dominated by the photolysis of nitrous acid accounting for 46% of the identified primary production pathways for RO x radicals. Other important radical sources were alkene ozonolysis (28%) and photolysis of oxygenated organic compounds (24%). A box model was used to 25 simulate the OH, HO 2 and RO 2 concentrations based on the observations of their long-lived precursors. The model was capable of reproducing the observed diurnal variation of the OH and peroxy radicals during clean days with a factor of 1.5. However, it largely underestimated HO 2 and RO 2 concentrations by factors up to 5 during pollution episodes. The HO 2 and RO 2 observed-to-modeled ratios increased with increasing NO concentrations, indicating a deficit in our understanding of the gas-phase chemistry in the high NO x regime. The OH concentrations observed in 30 the presence of large OH reactivities indicate that atmospheric trace gas oxidation by photochemical processes can be highly effective even during wintertime, thereby facilitating the vigorous formation of secondary pollutants.

<p><strong>Abstract.</strong> Nitryl chloride (ClNO<sub>2</sub>) is a dominant source of chlorine radical in polluted environment and can significantly affect the atmospheric oxidative chemistry. However, the abundance of ClNO<sub>2</sub> and its exact role are not fully understood under different environmental conditions. During the summer of 2014, we deployed a chemical ionization mass spectrometer to measure ClNO<sub>2</sub> and dinitrogen pentoxide (N<sub>2</sub>O<sub>5</sub>) at a rural site in the polluted North China Plain. Elevated mixing ratios of ClNO<sub>2</sub> (> 350 pptv) were observed at most of the nights with low levels of N<sub>2</sub>O<sub>5</sub> (< 200 pptv). The highest ClNO<sub>2</sub> mixing ratio of 2070 pptv (1-min average) was observed in a plume from megacity (Tianjin) and was characterized with faster N<sub>2</sub>O<sub>5</sub> heterogeneous loss rate and ClNO<sub>2</sub> production rate compared to average condition. The abundant ClNO<sub>2</sub> concentration kept increasing even after sunrise and reached a peak 4 hours later. Such highly sustained ClNO<sub>2</sub> peaks after sunrise are discrepant from the previously observed typical diurnal pattern. Meteorological and chemical analysis show that the sustained ClNO<sub>2</sub> morning peaks are caused by significant ClNO<sub>2</sub> production in the residual layer at night followed by downward mixing after break-up of the nocturnal inversion layer in the morning. We estimated that ~ 1.7–4.0 ppbv of ClNO<sub>2</sub> would exist in the residual layer in order to maintain the observed morning ClNO<sub>2</sub> peaks at the surface site. Observation-based box model analysis show that photolysis of ClNO<sub>2</sub> produced chlorine radical with a rate up to 1.12 ppbv h<sup>−1</sup>, accounting for 10–30 % of primary RO<sub><i>x</i></sub> production in the morning hours. The perturbation in total radical production leads to an increase of integrated daytime net ozone production by 3 % (4.3 ppbv) on average, and with a larger increase of 13 % (11 ppbv) in megacity outflow that was characterized with higher ClNO<sub>2</sub> and relatively lower OVOC to NMHC ratio.</p>

A comprehensive field campaign was carried out in summer 2014 in Wangdu located in the North China Plain. A month of continuous OH, HO 2 and RO 2 measurements were achieved.Observations of radicals by laser induced fluorescence (LIF) technique gave daily maximum concentrations between (5-15)×10 6 cm −3 , (3-14)×10 8 cm −3 and (3-15)×10 8 cm −3 for OH, HO 2 and RO 2 , respectively. Measured OH reactivities (inverse OH lifetimes) were 10 to 20 s −1 during day-5 time. A chemical box model constrained by trace-gas observations and based on a state-of-the-art chemical mechanism is used to interpret the observed radical concentrations. In general, the model can reasonably well reproduce measured radical concentrations during daytime. Like in previous field campaigns in China, modelled and measured OH concentrations agree for NO mixing ratios higher than 1 ppbv, but systematic discrepancies are observed in the afternoon for NO mixing ratios 10 of less than 300 pptv (the model-measurement ratio is between 1.4 to 2 in this case). If additional OH recycling equivalent to 100 pptv NO is assumed, the model is also capable of reproducing the observed OH concentrations for conditions of high VOC and low NO x concentrations with good agreement in HO 2 and RO 2 . Observed RO 2 concentrations are underestimated in the morning hours by a factor of 3 to 5. This indicates that an additional chemical source of RO 2 is missing in 15 the model. The OH reactivity is also underpredicted in the early morning. Increasing VOC concentrations to match measured OH reactivity helps to reduce the discrepancy between modelled and measured RO 2 . The underprediction of RO 2 coincides with high NO concentrations and therefore 1 Atmos. Chem. Phys. Discuss., leads to a significant underestimation of the local ozone production rates determined from the peroxy radical (HO 2 and RO 2 ) reactions with NO. The underestimation corresponds to a daily integral 20 ozone production of about 20 ppbv per day.2 Atmos. Chem. Phys. Discuss.,

Analysis of lipid functions suggested that the main reason for SS development in women might be a barrier dysfunction caused by excessive apoptosis and lack of water. Therefore, anti-allergy additives in cosmetic products that could inhibit apoptosis of keratinocytes and methods to maintain the stability of water molecules in the skin should be further studied.