Chemical Characterization and Source Profile of PM_2.5 from Firework Emissions in Chengdu, China

Air pollutants released from firework burning pose a potential threat to air quality and human health. To identify their emission characteristics and contributions, we conducted in-situ continuous measurements of the six criteria pollutants (i.e., NO₂, SO₂, O₃, CO, PM_2.5, and PM₁₀) along with chemical speciation in Chengdu during the Chinese New Year period (February 8–17, 2024). Results showed mass concentrations of PM_2.5, PM₁₀, and SO₂ increased by about 91%, 84%, and 52%, respectively, during the firework burning period (FBP) compared to the non-firework burning period (NFBP). During the peak burning hours, PM_2.5 varied substantially in composition. Characteristic radar chart (CRC) analysis and relative enrichment calculations identified Ba, Mg²⁺, Cu, and K⁺ (elemental K) as key markers, with relative enrichments exceeding 4. Firework-related chemical components accounted for about 70% of species contributions to PM_2.5 mass. The PM_2.5 source profile from fireworks emissions was characterized by a high abundance of potassium (K, 28%) and water soluble potassium (K⁺, 23%), with other contributions SO₄²⁻ (20%), Cl⁻ (13%), S (9%), Mg²⁺ (3%), Ba (3%), and trace amounts (< 1%) of Mn, Cu, Zn, and Pb. Positive matrix factorization (PMF) found that firework contributions to PM_2.5 peaked at 28% during the “Slightly Polluted” days (February 10–13), compared to only 3% and 7% during the initial “Good” and final “Good/Excellent/Floating Dust Aloft (FDA)” days, respectively. This study provides an integrated framework to quantitatively resolve firework emission profile and highlight key markers. Study supports targeted regulation of pyrotechnics to mitigate air pollution.