  Despite several national and local policies towards cleaner air in England,
many schools in London breach the WHO-recommended concentrations of air
pollutants such as NO2 and PM2.5. This is while, previous studies highlight
significant adverse health effects of air pollutants on children's health. In
this paper we adopted a Bayesian spatial hierarchical model to investigate
factors that affect the odds of schools exceeding the WHO-recommended
concentration of NO2 (i.e., 40 ug/m3 annual mean) in Greater London (UK). We
considered a host of variables including schools' characteristics as well as
their neighbourhoods' attributes from household, socioeconomic,
transport-related, land use, built and natural environment characteristics
perspectives. The results indicated that transport-related factors including
the number of traffic lights and bus stops in the immediate vicinity of
schools, and borough-level bus fuel consumption are determinant factors that
increase the likelihood of non-compliance with the WHO guideline. In contrast,
distance from roads, river transport, and underground stations, vehicle speed
(an indicator of traffic congestion), the proportion of borough-level green
space, and the area of green space at schools reduce the likelihood of
exceeding the WHO recommended concentration of NO2. As a sensitivity analysis,
we repeated our analysis under a hypothetical scenario in which the recommended
concentration of NO2 is 35 ug/m3, instead of 40 ug/m3. Our results underscore
the importance of adopting clean fuel technologies on buses, installing green
barriers, and reducing motorised traffic around schools in reducing exposure to
NO2 concentrations in proximity to schools. This study would be useful for
local authority decision making with the aim of improving air quality for
school-aged children in urban settings.
