<p>This study analyzed the impact of firework discharge on urban air quality during the Spring Festivals of 2022–2024 in Shandong Province, China, with a focus on PM₂.₅ concentration variations and their sources. Based on the monitoring data of conventional pollutants (SO₂, NO₂, PM₂.₅, PM₁₀, CO, and O₃) and chemical components of PM₂.₅ across 16 cities in Shandong Province, combined with meteorological conditions, the contribution of fireworks to PM₂.₅ and its source apportionment were evaluated, using the CO ratio method and positive matrix factorization (PMF) model. The results showed that PM₂.₅ concentrations surged significantly during the Spring Festival period in 2024, peaking at 423 µg/m³, which was 11.1 times and 1.2 times higher than those in 2022 and 2023, with fireworks contributing 49% to the daily average of PM₂.₅. During the concentrated discharge periods of fireworks (FCDP) in 2024, the proportions of NO₃⁻ and NH₄⁺ in PM_2.5 decreased by 21.5% and 10.7%, respectively, while those of tracer components of fireworks, such as K⁺, Cl⁻, SO₄²⁻, and Mg²⁺, increased by 17.2%, 7.7%, 5.9%, and 1.7%, respectively, showing the impact of fireworks. PMF source apportionment revealed that fireworks accounted for 59% of PM₂.₅ during the FCDP, rather than secondary sources (35%) and motor vehicles (21%) during the benchmark period (BP). The suggestions to the government were proposed, including strengthening policy implementation, optimizing discharge controls, and promoting public awareness of eco-friendly celebrations to reduce reliance on traditional fireworks.</p>