Accelerated reduction of atmospheric ultrafine particles since China VI vehicle emission standards
摘要
Vehicle emission is a major source of urban ultrafine particles (UFPs), yet measurement and emission control for UFP lags significantly behind that of other pollutants. The China VI emission standard, one of the strictest globally, introduced the nation’s first particle number (PN) limits. This study focused on real-world PN emissions in the capital city Beijing, which adopted China VI ahead of the national schedule in 2019. Based on long-term particle number size distribution measurements and online UFP composition analysis, a pronounced decline in emission rates of vehicle-attributed PN from 2019 to 2023 was found, resulting in decreases of ~70% for atmospheric PN3–30 nm, ~48% for PN30–100 nm, and ~42% for PN>100 nm. These reductions substantially outpace those observed for PM2.5 and NO2. Early implementation of China VI, coupled with rapid electric vehicle adoption, are the primary drivers behind Beijing’s more pronounced PN mitigation (−44%) compared with nationwide (−33%). These findings highlight the effectiveness of more stringent vehicle emission standards and electric vehicle strategies in reducing atmospheric UFPs, shedding light on future vehicle emission regulations.