Control Strategy Optimization for Attainment and Exposure Mitigation: Case Study for Ozone in Macon, Georgia

Implementation of more stringent 8-hour ozone standards has led the U.S. Environmental Protection Agency to designate nonattainment status to 474 counties nationwide, many of which had never previously violated air quality standards. As states select emission control measures to achieve attainment in these regions, their choices pose significant implications to local economies and the health of their citizens. Considering a case study of one such nonattainment region, Macon, Georgia, we develop a menu of potential controls that could be implemented locally or in neighboring parts of the state. The control menu offers the potential to control about 20–35% of ozone precursor emissions in most Georgia regions, but marginal costs increase rapidly beyond 15–20%. We link high-order ozone sensitivities with the control menu to identify cost-optimized strategies for achieving attainment and for alternative goals such as reducing spatially averaged or population-weighted ozone concentrations. Strategies targeted toward attainment of Macon ozone would prioritize local reductions of nitrogen oxides, whereas controls in the more densely populated Atlanta region are shown to be more effective for reducing statewide potential population exposure to ozone. A U.S. EPA-sanctioned approach for demonstrating ozone attainment with photochemical models is shown to be highly dependent on the choice of a baseline period and may not foster optimal strategies for assuring attainment and protecting human health.     

Relevant organic components in ambient particulate matter collected at Svalbard Islands (Norway)

n-Alkanes, polynuclear aromatic hydrocarbons and n-alkanoic acids present in the inhalable fraction of airborne particles have been determined at the Italian scientific base sited in the area of Ny Alesund, Spitzbergen Island, Norway. Both the profiles of n-alkane and polynuclear aromatic congeners among the respective classes showed that anthropogenic sources were responsible for the presence of particulate organics in the atmosphere there, since the monomodal distribution of aliphatics and the fresh-emission shape of PAH fraction were observed. The total contents of n-alkanes and PAH ranged from 19 to 97 ng m⁻³ and from 0.6 to 2.0 ng m⁻³, respectively; n-alkanoic acids reached 6 ng m⁻³. The occurrence of nitrated-PAH of photochemical origin at trace extent (i.e. nitrated-fluoranthenes and nitropyrenes) has been also observed. Since the occurrence of OH radicals is required together with NO_x for the processes leading to the generation of 2-nitrofluoranthene and 2-nitropyrene would start, the detection of these nitrated species revealed the occurrence of photochemical processes in that region.     

上海市环境空气NO2浓度时空分布特征

为监测机动车尾气造成的氧化型光化学烟雾的污染，采用被动扩散管的监测方法在上海布设65个监测点位，经13个月的连续监测，得出了上海市环境空气中NO2浓度时空分布特征及污染的重点区域，NO2时空分布主要特征：NO2高浓度值出现在交通主干道上（高架出口、隧道口、车辆堵塞的交通要道）；NO2浓度空间分布呈市中心区→市郊区→外围农村区逐渐减弱的趋势；总体时序分布呈秋冬季高于春夏季的变化趋势。     

Modeling of spatial and temporal variations of ozone-NOx-VOC sensitivity based on photochemical indicators in China

Comprehensive air quality model with extensions (CAMx)-decoupled direct method (DDM) was used to simulate ozone-NO_x-VOCs sensitivity of for May–November in 2016–2018 in China. Based on the relationship between the simulated ozone (O₃) sensitivity values and the ratio of formaldehyde (HCHO) to NO₂ (FNR) and the ratio of production rate of hydrogen peroxide (H₂O₂) to production rate of nitric acid (HNO₃) ($P_{{\mathrm{H}}_2{\mathrm{O}}_2}/P_{\text{HN}{\mathrm{O}}_3}$), the localized range of FNR and $P_{{\mathrm{H}}_2{\mathrm{O}}_2}/P_{\text{HN}{\mathrm{O}}_3}$ thresholds in different regions in China were obtained. The overall simulated FNR values are about 1.640–2.520, and $P_{{\mathrm{H}}_2{\mathrm{O}}_2}/P_{\text{HN}{\mathrm{O}}_3}$ values are about 0.540–0.830 for the transition regime. Model simulated O₃ sensitivities or region specific FNR or $P_{{\mathrm{H}}_2{\mathrm{O}}_2}/P_{\text{HN}{\mathrm{O}}_3}$ thresholds should be applied to ensure the accurate local O₃ sensitivity regimes. Using the tropospheric column FNR values from ozone monitoring instrument (OMI) satellite data as an indicator with the simulated threshold values, the spatial distributions of O₃ formation regimes in China are determined. The O₃ sensitivity regimes from eastern to central China are gradually from VOC-limited, transition to NO_x-limited spatially, and moving toward to transition or NO_x-limited regime from 2005 to 2019 temporally.