Excess vehicular evaporative emissions for prolonged parking during the COVID-19 lockdown in China.

Publication date: Sep 15, 2025

Vehicular evaporative emissions are major sources of urban volatile organic compounds (VOCs), significantly contributing to secondary organic aerosols (SOA) and ozone (O) formation. While most anthropogenic emissions declined during the COVID-19 lockdowns, the potential rise in evaporative emissions has been largely overlooked. Here, we integrate emission tests, parking data, and field measurements to assess excess evaporative emissions in China. Long-term experiments reveal that prolonged parking vehicles (> 5 days) experience up to an 18-fold increase in evaporative emissions compared to the first day. During the lockdown, prolonged parking events surged dramatically, driving a substantial increase in evaporative emissions, strongly corroborated by VOC source apportionment analysis. We estimate that annual evaporative emissions across 36 Chinese megacities rose by up to 2. 8-fold due to lockdown measures. These findings highlight prolonged parking as a critical yet underrecognized VOC source, emphasizing the need for improved regulatory control to mitigate urban air pollution.

Semantics

Original Article