Online single particle measurement of fireworks pollution during Chinese New Year in Nanning

Time-resolved single-particle measurements were conducted during Chinese New Year in Nanning, China. Firework displays resulted in a burst of SO₂, coarse mode, and accumulation mode (100–500 nm) particles. Through single particle mass spectrometry analysis, five different types of particles (fireworks-metal, ash, dust, organic carbon-sulfate (OC-sulfate), biomass burning) with different size distributions were identified as primary emissions from firework displays. The fireworks-related particles accounted for more than 70% of the total analyzed particles during severe firework detonations. The formation of secondary particulate sulfate and nitrate during firework events was investigated on single particle level. An increase of sulfite peak (80SO₃⁻) followed by an increase of sulfate peaks (97HSO₄⁻+ 96SO₄⁻) in the mass spectra during firework displays indicated the aqueous uptake and oxidation of SO₂ on particles. High concentration of gaseous SO₂, high relative humidity and high particle loading likely promoted SO₂ oxidation. Secondary nitrate formed through gas-phase oxidation of NO₂ to nitric acid, followed by the condensation into particles as ammonium nitrate. This study shows that under worm, humid conditions, both primary and secondary aerosols contribute to the particulate air pollution during firework displays.