Linking Carbon Footprints to Air-Pollutant Emissions from Mega Sporting Events: Evidence from the Beijing 2022 Winter Olympics

Mega sporting events report carbon footprints, but rarely describe the air pollutants that accompany them. This study links the verified greenhouse-gas inventory of the Beijing 2022 Winter Olympics (713,788 t CO2e, 2016–2022) to co-emitted NOx, SO2, PM2.5, CO and NMVOC in a screening-level, emission-side assessment using eight emission carriers with Chinese pollutant-to-CO2 ratios, Shapley attribution, and Monte Carlo and Sobol analyses. Construction accounted for 63% of the CO2e, an estimated 70% of the 1335 t of NOx, and 76% of the 279 t of PM2.5, remaining the largest NOx source in 99.9–100% of uncertainty draws and under alternative attributions. The measures taken, chiefly the employment of green electricity, avoided 31% of no-measure emissions and 18% of NOx under market-based accounting, but only 8% of NOx if green certificates were not used. Under literature-based assumptions, eight additional levers could have cut CO2e by 46% (41–53%) and NOx by 49%; zero-emission construction machinery avoids the most NOx per tonne of CO2. A residual of 384,375 t would remain; the offsets retired (2.4 times the emissions) reduced no air pollutants. For construction-dominated events, such as this pandemic-era edition, climate- and air-quality co-benefits are decided largely at the design stage, through materials and machinery, rather than by offsetting.