Heat stress in Beijing and its relationship with boundary layer structure and air pollution

Both extreme heat and heavy air pollution can cause adverse health impacts on urban inhabitants. To understand stress its relationship with boundary layer structure in Beijing, this study analyzed surface meteorological observations, radiosonde measurements, ground-level PM 2.5 O 3 concentrations summer from 2015 to 2019, conjunction simulated quality MERRA-2 data. We measured the using a index that combines temperature humidity quantify sensible as perceived by humans, found high risk Beijing was often associated low height poor quality. reveal underlying physical mechanism involved, we objectively classified synoptic conditions North China. The typical pattern coupling of feature southeast-to-north pressure gradient at 700-hPa level, leading westward warm advection above planetary (PBL) southward movement warm, humid, polluted masses within PBL towards Beijing. elevated enhance capping thermal inversion over suppress PBL's development vertical dispersion pollutants. With mountains north west, pollutants be trapped limited volume increasing pollution. These findings mechanisms between may have important implications for limiting current preparing any projected changes it future. • Strong event during found. Heat temperature-humidity combined metric. Physical heat-pollution revealed.