Halogen ( Cl , Br, and I) chemistry has been reported to influence the formation of secondary air pollutants. Previous studies mostly focused on the impact of chlorine species on air quality over large spatial scales. Very little attention has been paid to the effect of the combined halogen chemistry on air quality over Europe and its implications for control policy. In the present study, we apply a widely used regional model, the Community Multiscale Air Quality Modeling System (CMAQ), incorporated with the latest halogen sources and chemistry, to simulate the abundance of halogen species over Europe and to examine the role of halogens in the formation of secondary air pollution. The results suggest that the CMAQ model is able to reproduce the level of O 3 , NO 2 , and halogen species over Europe. Chlorine chemistry slightly increases the levels of OH , HO 2 , NO 3 , O 3 , and NO 2 and substantially enhances the level of the Cl radical. Combined halogen chemistry induces complex effects on OH (ranging from −0.023 to 0.030 pptv) and HO 2 (in the range of −3.7 to 0.73 pptv), significantly reduces the concentrations of NO 3 (as much as 20 pptv) and O 3 (as much as 10 ppbv), and decreases NO 2 in highly polluted regions (as much as 1.7 ppbv); it increases NO 2 (up to 0.20 ppbv) in other areas. The maximum effects of halogen chemistry occur over oceanic and coastal regions, but some noticeable impacts also occur over continental Europe. Halogen chemistry affects the number of days exceeding the European Union target threshold for the protection of human beings and vegetation from ambient O 3 . In light of the significant impact of halogen chemistry on air quality, we recommend that halogen chemistry be considered for inclusion in air quality policy assessments, particularly in coastal cities.
Halogen (Cl, Br, and I) chemistry has been reported to influence the formation of secondary air pollutants. Previous studies mostly focused on the impact of chlorine species on air quality over large spatial scales. Very little attention has been paid to the effect of the combined halogen chemistry on air quality over Europe and its implications for control policy. In the present study, we apply a widely used regional model, the Community Multiscale Air Quality Modeling System (CMAQ), incorporated with the latest halogen sources and chemistry, to simulate the abundance of halogen species over Europe and to examine the role of halogens in the formation of secondary air pollution. The results suggest that the CMAQ model is able to reproduce the level of O3, NO2, and halogen species over Europe. Chlorine chemistry slightly increases the levels of OH, HO2, NO3, O3, and NO2 and substantially enhances the level of the Cl radical. Combined halogen chemistry induces complex effects on OH (ranging from −0.023 to 0.030 pptv) and HO2 (in the range of −3.7 to 0.73 pptv), significantly reduces the concentrations of NO3 (as much as 20 pptv) and O3 (as much as 10 ppbv), and decreases NO2 in highly polluted regions (as much as 1.7 ppbv); it increases NO2 (up to 0.20 ppbv) in other areas. The maximum effects of halogen chemistry occur over oceanic and coastal regions, but some noticeable impacts also occur over continental Europe. Halogen chemistry affects the number of days exceeding the European Union target threshold for the protection of human beings and vegetation from ambient O3. In light of the significant impact of halogen chemistry on air quality, we recommend that halogen chemistry be considered for inclusion in air quality policy assessments, particularly in coastal cities.
Halogen (Cl, Br, and I) chemistry has been reported to influence the formation of secondary air pollutants. Previous studies mostly focused on the impact of chlorine species on air quality over large spatial scales. Very little attention has been paid to the effect of the combined halogen chemistry on air quality over Europe and its implications for control policy. In the present study, we apply a widely used regional model, the Community Multiscale Air Quality Modeling System (CMAQ), incorporated with the latest halogen sources and chemistry, to simulate the abundance of halogen species over Europe and to examine the role of halogens in the formation of secondary air pollution. The results suggest that the CMAQ model is able to reproduce the level of O(3), NO(2), and halogen species over Europe. Chlorine chemistry slightly increases the levels of OH, HO(2), NO(3), O(3), and NO(2) and substantially enhances the level of the Cl radical. Combined halogen chemistry induces complex effects on OH (ranging from –0.023 to 0.030 pptv) and HO(2) (in the range of –3.7 to 0.73 pptv), significantly reduces the concentrations of NO(3) (as much as 20 pptv) and O(3) (as much as 10 ppbv), and decreases NO(2) in highly polluted regions (as much as 1.7 ppbv); it increases NO(2) (up to 0.20 ppbv) in other areas. The maximum effects of halogen chemistry occur over oceanic and coastal regions, but some noticeable impacts also occur over continental Europe. Halogen chemistry affects the number of days exceeding the European Union target threshold for the protection of human beings and vegetation from ambient O(3). In light of the significant impact of halogen chemistry on air quality, we recommend that halogen chemistry be considered for inclusion in air quality policy assessments, particularly in coastal cities.
The present work was supported by the Spanish Ministry of Agriculture, Fishing, Food and Environment, the Madrid City Council and Madrid Regional Government, and by the Ministry of Economy, Industry and Competitiveness and FEDER funds under the project HOUSE (CGL2016-78594-R) and the Generalitat de Catalunya (AGAUR 2017 SGR41). Part of this research was supported by the Korea Ministry of Environment through "The Eco-Innovation project". Support is also acknowledged from the CUD of Zaragoza (project CUD 2016-05), UPV/EHU (UFI 11/47, GIU 16/03), the project PROACLIM CGL2014-52877-R, the City Council of Majadahonda for logistic support, AEMET for providing surface meteorological data, and data from radio soundings and ozone free soundings. ; Various studies have reported that the photochemical nucleation of new ultrafine particles (UFPs) in urban environments within high insolation regions occurs simultaneously with high ground ozone (O3) levels. In this work, we evaluate the atmospheric dynamics leading to summer O3 episodes in the Madrid air basin (central Iberia) by means of measuring a 3-D distribution of concentrations for both pollutants. To this end, we obtained vertical profiles (up to 1200 m above ground level) using tethered balloons and miniaturised instrumentation at a suburban site located to the SW of the Madrid Metropolitan Area (MMA), the Majadahonda site (MJDH), in July 2016. Simultaneously, measurements of an extensive number of air quality and meteorological parameters were carried out at three supersites across the MMA. Furthermore, data from O3 soundings and daily radio soundings were also used to interpret atmospheric dynamics. The results demonstrate the concatenation of venting and accumulation episodes, with relative lows (venting) and peaks (accumulation) in O3 surface levels. Regardless of the episode type, the fumigation of high-altitude O3 (arising from a variety of origins) contributes the major proportion of surface O3 concentrations. Accumulation episodes are characterised by a ...
