Local synergies and antagonisms between meteorological factors and air pollution: A 15-year comprehensive study in the Sydney region

GiuliaUlpiani GianlucaRanzi MatSantamouris
Science of The Total Environment

Volume 788, 20 September 2021, 147783



Associated with rapid urbanization and escalation of bushfire events, Sydney has experienced significant air quality degradation in the XXI century. In this study, we present a 15-year retrospective analysis on the influence of individual meteorological factors on major air pollutants (NO2, O3, PM10 and PM2.5) at 14 different sites in Greater Sydney and Illawarra. By applying a newly developed “zooming in” approach to long-term ground-based data, we disclose general, seasonal, daily and hourly patterns while increasing the level of spatial associativity. We provide evidence on the pivotal role played by urbanization, sprawling dynamics, global warming and bushfires on local meteorology and air pollution. We strike associations between temperature and O3, both as average trends and extremes, on account of increasing heat island effects. The role of wind in a coastal-basin environment, influenced by a vast desert biome inland, is investigated. A steady trend towards stagnation is outlined, boosted by enhanced urban roughness and intensified heat island circulation. Relative humidity is also crucial in the modulation between NO2 and O3. With a sharp tendency towards drier and hotter microclimates, NO2 levels dropped by approximately 50% over the years at all locations, while O3's median levels almost doubled in the last 10 years. Further, O3 and PMs shifted towards more frequent extreme events, strongly associated with the exacerbation of bushfire events. Such results suggest an urgent need to prioritize emission control, building air tightness improvement and urban heat mitigation, towards a future-proof governance in Sydney and similar regions in the world.