“…Studies have shown that the relationship between PM 2.5 and AOD is not always suitable for simple regression models. Rather it is determined by a multi-variate function of a large number of parameters, including: humidity, temperature, boundary layer height, surface pressure, population density, topography, wind speed, surface type, surface reflectivity, season, land use, normalised variance of rainfall events, size spectrum and phase of cloud particles, cloud cover, cloud optical depth, cloud top pressure and the proximity to particulate sources releasing PM 2.5 (Liu et al, 2005;Lyamani et al, 2006;Choi et al, 2008;Paciorek et al, 2012;). The picture is further complicated by the biases present in satellite AOD products (e.g.…”