Filter samples of fine particulate matters were collected at four sites in northern China (urban, rural, and mountain) in summer and winter, and the contents of nine nitrated phenols were quantified in the laboratory with the use of ultra-high-performance liquid chromatography coupled with mass spectrometry. During the sampling periods, the concentrations of particulate nitrated phenols exhibited distinct temporal and spatial variation. On average, the total concentration of particulate nitrated phenols in urban Jinan in the wintertime reached 48.4 ng m⁻³, and those in the summertime were 9.8, 5.7, 5.9, and 2.5 ng m⁻³ in urban Jinan, rural Yucheng and Wangdu, and Mt. Tai, respectively. The elevated concentrations of nitrated phenols in wintertime and in urban areas demonstrate the apparent influences of anthropogenic sources. The positive matrix factorization receptor model was then applied to determine the origins of particulate nitrated phenols in northern China. The five major source factors were traffic, coal combustion, biomass burning, secondary formation, and aged coal combustion plume. Among them, coal combustion played a vital role, especially at the urban site in the wintertime, with a contribution of around 55 %. In the summertime, the observed nitrated phenols were highly influenced by aged coal combustion plumes at all of the sampling sites. Meanwhile, in remote areas, contributions from secondary formation were significant. Further correlation analysis indicates that nitrosalicylic acids were produced mostly from secondary formation that was dominated by NO₂ nitration.

Fireworks displays are a traditional form of celebration during the Chinese Spring Festival (Festival). In response to the heavy air pollution caused by fireworks, Shanghai, a megacity in China, has imposed regulatory measures on the use of fireworks in recent years. To investigate air quality trends before and after firework regulation was established and quantify its efficiency, gaseous pollutants, PM2.5 levels, and PM2.5 chemical composition were synchronously measured at 1 h time intervals at an urban site and a suburban site in Shanghai in the period during and around the Festival from 2013 to 2017. PM2.5 concentrations at the urban site during the Festival over the five-year period were 79 (max: 524), 94 (290), 53 (163), 50 (146) and 32 (156) μg/m3, respectively, presenting a decreasing trend at a rate of -13.8 μg/m3/yr (p = 0.05). K+ concentrations, which serve as a tracer of fireworks, were 8.2 (max: 159.4), 2.5 (14.6), 2.2 (10.4), 4.3 (44.2) and 0.8 (4.5) μg/m3 during the Festival from 2013 to 2017, respectively, and thus decreased at a rate of -1.3 μg/m3/yr (p = 0.17). Accordingly, fireworks contributed 41 (51.9%), 38 (36.5%), 6 (10.3%), 21 (35.6%), and 4 μg/m3 (12.1%) to PM2.5, respectively, implying the effectiveness of firework regulation in Shanghai. Health effects attributed to PM2.5 pollution in Shanghai during the Festival were assessed based on Poisson regression. The number of premature deaths related to short-term PM2.5 exposure in Shanghai during the Festival from 2013 to 2017 was 75 (95% CI: 27, 108), 92 (30, 129), 55 (18, 76), 49 (19, 70), and 31 (12, 45), respectively. Daily mortality due to PM2.5 exposure during the Festival from 2013 to 2017 accounted for 1.4-3.8% of total daily mortality in Shanghai. This study provides scientific evidence of air quality improvement and the effectiveness of firework regulation in Shanghai.