Proximity to busy highways and local resident perceptions of air quality

This study investigated variations in perceptions of air quality as a function of residential proximity to busy highways, across two suburbs of South Auckland, New Zealand. While plenty is known about the spatial gradients of highway emissions, very little is known about variation of lay understanding at the fine spatial scale and whether there are gradients in severity of concerns. One-hundred and four near-highway residents agreed to participate in a semi-structured interview on their knowledge and attitudes towards highway traffic emissions. Proximity to the highway edge varied within 5-380 m at the predominantly downwind side of the highway and 13-483 m at the upwind side. Likert-type ordered response questions were analysed using multivariate regression. Inverse linear relationships were identified for distance from highway and measures of concern for health impacts, as well as for noise (p<0.05). Positive linear relationships were identified for distance from highway and ratings of both outdoor and indoor air quality (p<0.05). Measures of level of income had no conclusive statistically significant effect on perceptions. Additional discussion was made surrounding participant's open-ended responses, within the context of limited international research. Findings indicate that there may be quantifiable psychological benefits of separating residents just a short distance (40 m+) from highways and that living within such close proximity can be detrimental to wellbeing by restricting local outdoor activity. This work lends additional rationale for a residential separation buffer of ~100 m alongside major highways in the interests of protecting human health.