Long term trends in global air pollution potential and its application to ventilation corridors

Abstract

Air pollution potential is a measure of the inability of the atmosphere to disperse pollutants away from the source. It depends on Planetary Boundary Layer Height (PBLH) and wind speed. Global air pollution potential Index (APPI) maps have been generated for the first time using 40 years (1980–2019) of PBLH and wind speed data available from ECMWF Reanalysis v5 (ERA5) data. These are useful for identifying ventilation corridors and for sustainable development. The seasonal climatology of APPI is also analyzed. Long-term trends in Ventilation coefficient (VC), PBLH, Wind speed, PM_2.5, and Aerosol Optical Thickness (AOT) were analyzed globally and in over 30 cities to understand their future impact on climate change scenarios. High APPI is observed in the South Asian regions, giving rise to PM_2.5 and AOT hot spots, and are naturally disadvantageous. Long-term trends in VC and associated trends in PBLH and Wind speed suggest that the PBLH is decreasing at the rate of 1–3 m per year over south Asia, and wind speed is decreasing at the rate of 0.01–0.02 m·s^− 1per year, resulting in the decrease of VC of about 1–25 m²·s^− 1per year. If this trend continues, South Asia will have more air pollution potential, causing severe stagnation of air pollutants in the coming years and putting health risks to 1.8 billion people. The surface PM_2.5 and AOT are increasing at 0.5–1.5 µg·m^− 3 per year and 0.005–0.01 per year for South Asia cities. Sustainable development goals and climate policies/negotiations should consider global air pollution potential as an essential variable in planning and mitigation.