Significant annual variations of firework-impacted aerosols in Northeast China: Implications for rethinking the firework bans

Fireworks are banned in many Chinese cities but never eliminated, reflecting strong public demand on this traditional activity for festival celebrations. On the other hand, the assessment of firework contributions to air pollution remains vague, raising concerns on the necessity of the mandatory bans. Here we investigated the characteristics of firework episodes in a megacity in Northeast China, based on field campaigns conducted in four successive winters during 2018–2022. Although prohibited, the firework influences remained evident during the Chinese New Year periods, as suggested by the enhancements of water-soluble potassium (K⁺). In addition, significant annual variations were identified for the firework episodes, with the following features observed. First, the firework-induced enrichment ratios of K⁺ and chloride exhibited increasing trends across years, climbing from 4.4 to 8.6 and from 1.7 to 2.9, respectively. Second, the enrichment ratio of sulfate dropped from 2.8 to 1.6, indicating that the firework contributions to sulfate decreased but remained considerable. Third, fireworks turned into an unimportant source for organic carbon and nitrate in the most recent winter of 2021–2022, with enrichment ratios of ∼1 for both species. Fourth, the firework-driven increases in fine particle concentration were as high as ∼100% for the two winters during 2019–2021, whereas the increase dropped sharply to ∼30% for 2021–2022. These variations were in line with the promotion of environmentally friendly fireworks. Our results indicated that the air pollution caused by fireworks could be reduced substantially by advanced manufacturing technologies and thus it is time to rethink the firework bans.