Although ambient PM2.5 has been linked to adverse health effects, the chemical constituents that cause harm are largely unclear. Few prior studies in a developing country have reported the health impacts of PM2.5 constituents. In this study, we examined the short-term association between PM2.5 constituents and emergency room visits in Shanghai, China. We measured daily concentrations of PM2.5, organic carbon (OC), elemental carbon (EC), and eight water-soluble ions between January 1, 2011 and December 31, 2012. We analyzed the data using overdispersed generalized linear Poisson models. During our study period, the mean daily average concentration of PM2.5 in Shanghai was 55 μg/m(3). Major contributors to PM2.5 mass included OC, EC, sulfate, nitrate, and ammonium. For a 1-day lag, an interquartile range increment in PM2.5 mass (36.47 μg/m(3)) corresponded to 0.57% [95% confidence interval (CI): 0.13%, 1.01%] increase of emergency room visits. In all the three models used, we found significant positive associations of emergency room visits with OC and EC. Our findings suggest that PM2.5 constituents from the combustion of fossil fuel (e.g., OC and EC) may have an appreciable influence on the health impact attributable to PM2.5.

Chamber experiments, exhaust collection, and in-situ sampling were employed to study the emission profiles of volatile organic compounds (VOCs) from solvent use, specifically indoor paint, auto paint, furniture paint, and print ink, which are of significant importance with regard to VOC emissions in Shanghai. The results showed that there were some differences among these VOC source profiles of the emissions associated with different solvents. On the one hand, for emissions from imported indoor solvents, ~50% of the total mass concentration was contributed by aromatics, and ~30% by alkanes. On the other hand, VOC source profiles from domestic indoor paint, furniture paint, and auto paint were similar in the sense that aromatics made a much larger contribution to total VOCs, specifically, 98% for domestic indoor paint, 80%-93% for the other two, and C8-C9 aromatics accounted for ~70% of total VOCs. For VOCs from printing, C2-C5 species dominated by more than 50%, followed by C8-C9 aromatics. VOCs from the use of different solvents presented different chemical reactivities. Among the four solvents listed above, the average OH loss rate constant (k-avg) and maximum incremental reactivity (MIR-avg) of VOCs from printing were the lowest, with values of 8.2 × 10 -12 cm 3 /molecule/s and 2.9 g(O 3 )/g(VOC), respectively. For VOCs from painting, the average reactivity was twice that of VOCs from printing, and its value of MIR-avg was 4.7-6.3 g(O 3 )/g(VOC). There are significant variations in the VOC source profiles related to solvent use in different studies. The representativeness of the solvents studied and the VOC samples collected should thus be more closely examined. The accuracy of VOC source profiles related to solvent use is highly dependent on location and sampling frequency.

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This study focuses on the month-to-month variability of winter temperature anomalies over Northeast China (NECTA), especially the out-of-phase change between December and January–February (colder than normal in December and warmer than normal in January–February, and vice versa), which accounts for 30% of the past 37 years (1980–2016). Our analysis shows that the variability of sea ice concentration (SIC) in the preceding November over the Davis Strait–Baffin Bay (SIC_DSBB) mainly affects NECTA in December, whereas the SIC over the Barents–Kara Sea (SIC_BKS) significantly impacts NECTA in January–February. A possible reason for the different effects of SIC_DSBB and SIC_BKS on NECTA is that the month-to-month increments (here called DM) of SIC over these two areas between October and November are different. A smaller DM of SIC_DSBB in November can generate eastward-propagating Rossby waves toward East Asia, whereas a larger DM of SIC_BKS can affect upward-propagating stationary Rossby waves toward the stratosphere in November. Less than normal SIC_DSBB in November corresponds to a negative phase of the sea surface temperature tripole pattern over the North Atlantic, which contributes to a negative phase of the North Atlantic Oscillation (NAO)-like geopotential height anomalies via the eddy-feedback mechanism, ultimately favoring cold conditions over Northeast China. However, positive November SIC_BKS anomalies can suppress upward-propagating Rossby waves that originate from the troposphere in November, strengthening the stratospheric polar vortex and leading to a positive phase of an Arctic Oscillation (AO)-like pattern in the stratosphere. Subsequently, these stratospheric anomalies propagate downward, causing the AO-like pattern in the troposphere in January–February, favoring warm conditions in Northeast China, and vice versa.