Modelling environmental equity: access to air quality in Birmingham, England

Many studies in the USA have noted inequities with regard to the socioeconomic status or racial character of communities and their relative exposure to environmental disamenities. In this paper the authors focus particularly on the environmental equity of air pollution in the English city of Birmingham. Using statistical methodologies they examine the pattern of exposure to two key air pollutants: carbon monoxide (CO) and nitrogen dioxide (NO,) across certain population groups in the city. Estimated emission levels of CO and NO2 were mapped by using modelled associations between vehicle densities and measured emissions at existing monitoring stations. These data were input to a geographical information system (GIS) for subsequent comparisons with population maps. Three types of variables were considered to distinguish possibly disadvantaged populations: age profile, ethnic make-up, and poverty indicators. From the 1991 Census, relevant statistics were derived for each enumeration district in the city. No relationship could be established on the age variable (that is, neither children nor pensioners appear to differ from the general population in their likely exposure patterns). However, there was a striking relationship between modelled emissions and poverty indicators and ethnicity. The effects are difficult to separate out but there is strong evidence to suggest that the two factors (poverty and ethnicity) operate in an independent manner. The implications of these findings, with regard to the causes of the disparities and the likely impacts of possible efforts to improve air quality in Birmingham, are discussed.