Higher population density is associated with worse air quality and related health outcomes in Tāmaki Makaurau.

Abstract

Objectives: To explore associations between population density, air pollution concentrations, and related health outcomes in Tāmaki Makaurau Auckland, Aotearoa New Zealand.

Methods: Concentrations of nitrogen dioxide (NO₂) and fine particulate matter (PM_2.5) and associated health outcomes (premature mortality, cardiovascular and respiratory hospitalisations, and childhood asthma) were obtained from the Health and Air Pollution in New Zealand 2016 study. The possible mediating factors assessed were motor vehicle traffic, domestic fires, local industry, and green space.

Results: Higher population density was associated with higher concentrations of NO₂ (β: 0.18, p < 0.01) and PM_2.5 (β: 0.04, p < 0.01). Adverse health outcomes related to NO₂ and respiratory hospitalisations attributed to PM_2.5 exposure increased incrementally with the density of urban areas. The mediating factor with the strongest effect was motor vehicle traffic.

Conclusions: Higher population density in Auckland is associated with worse air quality and related health outcomes. Motor vehicle traffic is the most important source of pollution and is highest in the most densely populated parts of the city.

Implications for public health: Housing intensification in Auckland will likely increase ill health from air pollution unless steps are taken to reduce exposure to emissions from motor vehicles.