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Occupational exposure to welding fumes constitutes a serious health concern. Although the effects of fumes on the respiratory tract have been investigated, few apparent reports were published on their effects on the skin. The purpose of this study was to investigate the effects of exposure to welding fumes on skin cells, focusing on interleukin-24 (IL-24), a cytokine involved in the pathophysiology of skin conditions, such as atopic dermatitis and psoriasis. Treatment with welding fumes increased IL-24 expression and production levels in human dermal microvascular endothelial cells (HDMEC) which were higher than that in normal human epidermal keratinocytes. IL-24 levels in Trolox and deferoxamine markedly suppressed welding fume-induced IL-24 expression in HDMEC, indicating that oxidative stress may be involved in this cytokine expression. IL-24 released from HDMEC protected keratinocytes from welding fume-induced damage and enhanced keratinocyte migration. Serum IL-24 was higher in welding workers than in general subjects and was positively correlated with elevated serum levels of 8-hydroxy-2'-deoxyguanosine, an oxidative stress marker. In summary, welding fumes enhanced IL-24 expression in HDMEC, stimulating keratinocyte survival and migration. IL-24 expression in endothelial cells may act as an adaptive response to welding-fume exposure in the skin. [ABSTRACT FROM AUTHOR]

The impacts of renewable energy shifting, passenger car electrification, and lightweighting through 2050 on the atmospheric concentrations of PM2.5 total mass and oxidative stress‐inducing metals (PM2.5‐Fe, Cu, and Zn) in Japan were evaluated using a regional meteorology–chemistry model. The surface concentrations of PM2.5 total mass, Fe, Cu, and Zn in the urban area decreased by 8%, 13%, 18%, and 5%, respectively. Battery electric vehicles (BEVs) have been considered to have no advantage in terms of non‐exhaust PM emissions by previous studies. This is because the disadvantages (heavier weight increases tire wear, road wear, and resuspention) offset the advantages (regenerative braking system (RBS) reduces brake wear). However, the future lightweighting of drive battery and body frame were estimated to reduce all non‐exhaust PM. Passenger car electrification only reduced PM2.5 concentration by 2%. However, Fe and Cu concentrations were more reduced (−8% and −13%, respectively) because they have high brake wear‐derived and significantly reflects the benefits of BEV's RBS. The water‐soluble fraction concentration of metals (induces oxidative stress in the body) was estimated based on aerosol acidity. The reduction of SOx, NOx, and NH3 emissions from on‐road and thermal power plants slightly changed the aerosol acidity (pH ± 0.2). However, it had a negligible effect on water‐soluble metal concentrations (maximum +2% for Fe and +0.5% for Cu and Zn). Therefore, the metal emissions reduction was more important than gaseous pollutants in decreasing the water‐soluble metals that induces respiratory oxidative stress and passenger car electrification and lightweighting were effective means of achieving this. Plain Language Summary: Water‐soluble metals in PM2.5 induce respiratory oxidative stress. Gaseous pollutants increase the aerosol acidity and contribute to metal dissolution. In this study, the effects of renewable energy shifting, passenger car electrification, and lightweighting by 2050 on the atmospheric concentrations of PM2.5 total mass, Fe, Cu, and Zn and aerosol acidity in Japan were evaluated using atmospheric simulation. Since the regenerative braking system (RBS) of battery electric vehicles (BEVs) have lower brake wear emissions than those of conventional vehicles, the penetration of BEVs was effective in reducing the concentrations of Fe and Cu, which have high brake wear dependence (−13% and −18%, respectively, in urban area). Current BEVs increase tire and road wear and resuspension‐derived PM emissions due to their heavy weight, which can be avoided by lightweighting technologies through 2050. The reduction of gaseous pollutants from thermal power plants and on‐road slightly changed aerosol acidity, but the effect on water‐soluble metal concentrations was small. Therefore, it was suggested that reducing primary metal emissions is more important than gaseous pollutants in decreasing concentration of water‐soluble metals that are harmful to the respiratory system, and that vehicle electrification and lightweighting are effective means for that. Key Points: Vehicle electrification effectively reduced the concentrations of PM2.5‐Fe and Cu, which are toxic to respiratory oxidative stressThe lightweighting of battery electric vehicles reduced all non‐exhaust PM from tire, brake, road wear, and resuspensionChanges in aerosol acidity due to gaseous pollutants reduction had little effect on the water‐solubility of metals [ABSTRACT FROM AUTHOR]

A regional meteorology–chemistry model was used to evaluate the impact of battery electric vehicles (BEV) penetration on summer O3 concentrations in Kanto (Japan's most populous region). When all passenger cars shifted to BEVs, daytime ozone (O3) concentrations decreased over a wide area. The reduction of vehicle exhaust reduced O3 in inland suburban areas (NOx‐limited) and the reduction of gasoline fuel evaporation from vehicles and gas stations reduced O3 in urban areas (volatile organic compound (VOC)‐limited). The maximum location of maximum daily 8‐hr average O3 (MDA8hO3) sensitivity (−5%; −5 ppb) was at midway between urban and suburban areas, to which the reduction of exhaust and fuel evaporation contributed equally, respectively. The additional emissions from thermal power plants due to BEV's night‐charging could cause up to ±5% sensitivity to next‐day surface O3 concentrations topically. Depending on the O3 sensitivity regime (NOx‐ or VOC‐limited), additional NOx‐rich plumes from rural (urban) power plants tended to increase (decrease) the next day's O3. However, the spatial distribution of the regime varies temporally depending on such as NOx/VOC emission ratios and meteorological conditions. This study indicated that the distribution of negative (positive) O3 sensitivity by NOx‐rich plume is consistent with that of small (large) H2O2/HNO3 concentration ratios, indicating that H2O2/HNO3 works well as an indicator to discriminate O3 sensitivity regimes. Utilization of the H2O2/HNO3 indicator would enable regime distribution predictions without sensitivity simulations with varying NOx and VOC emissions, which would contribute to reducing computational costs. Plain Language Summary: Ozone (O3), which causes respiratory health effects, is formed in the atmosphere by its precursors NOx and volatile organic compound (VOC). Conventional gasoline vehicle exhaust is a major source of NOx and VOC, gasoline fuel VOC evaporate from vehicles and gas stations and thermal power plants emit mainly NOx. This study evaluated the impact of BEV penetration on summer O3 concentrations in Kanto using numerical simulation. When all passenger cars shifted to BEVs, daytime O3 concentrations decreased over a wide area in Kanto (up to −5%). The additional emissions from thermal power plants due to BEV night‐charging had a ±5% impact on next‐day O3 concentration topically. O3 has a NOx‐ or VOC‐sensitive region (called O3 sensitivity regime), and different effective NOx‐VOC emission measure. The above sensitivity was explained by the emission change by BEV shifting and the O3 sensitivity regime distribution. The spatial distribution of the regime varies temporally depending on NOx/VOC emission ratios and meteorological conditions. This study also indicated that H2O2/HNO3 is a useful indicator for its discrimination. Utilization of the H2O2/HNO3 indicator would enable regime distribution predictions without sensitivity simulations with varying NOx and VOC emissions, which is originally required, and would contribute to reducing computational costs. Key Points: The impact of battery electric vehicle (BEV) penetration on summer O3 concentrations in the Kanto region of Japan was evaluatedDaytime O3 decreased in both urban and inland suburban areasAdditional NOx emission from power plants due to night‐charging for BEV affected next day daytime O3 depending on meteorological conditions [ABSTRACT FROM AUTHOR]