Air pollution and environmental injustice in Hong Kong : are socially deprived groups exposed to more air pollution?

Environmental injustice has received high attention in the field of environmental studies. The concept of environmental justice is well defined within different academic disciplines. It refers to the rightness, fairness, and equity that a person in his own living environment is entitled to. In contrast, environmental injustice refers to the failure for one to receive the environmental justice that he is entitled to. Environmental injustice has been well substantiated by numerous international studies and evidenced in many countries overseas. A key question thus emerges: Is environmental injustice well evidenced in Hong Kong? Air pollution presents a major environmental challenge to the socially deprived communities both internationally and locally. Whilst the relationship between air pollution and social deprivation is well established internationally, given the strong evidence supporting the hypothesis that the socially deprived are exposed to more air pollution, the validity of such claim in the local context is not as obvious. Existing local studies investigating the relationship between air pollution and social deprivation are limited by, first, the lack of fine-grained air pollution data at a smaller geographical scale, which constrains the observation and conclusion of such hypothesis at a more refined geographical scale (Stern, 2003) and second, a stronger tendency to focus on the vulnerability of air pollution on different socio-economic spectrums (C. M. Wong et al., 2008). The current study aims to close the research gap by (a) developing a sophisticated methodology to enhance the collection and analysis of air pollution data at the Territorial Planning Unit, (b) examining the relationship between air pollution exposure and social deprivation at the TPU level, and (c) examining whether environmental injustice in relation to air pollution exists in Hong Kong. Our key research questions thus include the following: (1) Are the socially deprived in Hong Kong exposed to more air pollution? (2) Can we break through the existing methodological constraint and develop a brand new sophisticated air pollution data estimation methodology to interpolate air pollution at a smaller geographical scale? (3) If (1) is positive, would the exposure to more air pollution by the socially deprived in Hong Kong constitute the case of environmental injustice? A more sophisticated and accurate air pollution estimation methodology to estimate air pollution at a smaller geographical scale with the least root mean square error (RMSE) as compared to other key traditional models is introduced. The model identifies key spatial factors that affect the dispersion of air pollution in Hong Kong. By regression analysis, it is shown that the relationship between exposure to air pollution and social deprivation is positive and statistically significant. Both NO2 and PM10, the two major road-based pollutants, are positively correlated with the social deprivation index (for NO2: coefficient=0.4404 R= 0.6937, p<0.01; for PM10: coefficient = 0.4185, R = 0.6430, p