Investigating the Potential of Land Use Modifications to Mitigate the Respiratory Health Impacts of NO2: A Case Study in the Portland-Vancouver Metropolitan Area

Abstract

The health impacts of urban air pollution are a growing concern in our rapidly urbanizing world. Urban air pollutants show high intra-urban spatial variability linked to urban land use and land cover (LULC). This correlation of air pollutants with LULC is widely recognized; LULC data is an integral input into a wide range of models, especially land use regression models developed by epidemiologists to study the impact of air pollution on human health. Given the demonstrated links between LULC and urban air pollution, and between urban air pollution and health, an interesting question arises: what is the potential of LULC modifications to mitigate the health impacts of urban air pollution?In this dissertation we assess the potential of LULC modifications to mitigate the health impacts of NO 2 , a respiratory irritant and strong marker for combustionrelated air pollution, in the Portland-Vancouver metropolitan area in northwestern USA. We begin by measuring summer and winter NO 2 in the area using a spatially dense network of passive NO 2 samplers. We next develop an annual average model for NO 2 based on the observational data, using random forestfor the first time in the realm of urban air pollution -to disentangle the effects of highly correlated LULC variables on ambient NO 2 concentrations. We apply this random forest (LURF) model to a 200m spatial grid covering the study area, and use this 200m LURF model to quantify the effect of different urban land use ii categories on ambient concentrations of NO 2 . Using the changes in ambient NO 2 concentrations resulting from land use modifications as input to BenMAP (a health benefits assessment tool form the US EPA), we assess the NO 2 -related health impact associated with each land use category and its modifications. We demonstrate how the LURF model can be used to assess the respiratory health benefits of competing land use modifications, including city-wide and local-scale mitigation strategies based on modifying tree canopy and vehicle miles traveled (VMT).Planting trees is a common land cover modification strategy undertaken by cities to reduce air pollution. Statistical models such as LUR and LURF demonstrate a correlation between tree cover and reduced air pollution, but they cannot demonstrate causation. Hence, we run the atmospheric chemistry and transport model CMAQ to examine to what extent the dry deposition mechanism can explain the reduction of NO 2 which statistical models associate with tree canopy.Results from our research indicate that even though the Portland-Vancouver area is in compliance with the US EPA NO 2 standards, ambient concentrations of NO 2 still create an annual health burden of at least $40 million USD. Our model suggests that NO 2 associated with high intensity development and VMT may be creating an annual health burden of $7 million and $3.3 million USD respectively.Existing tree canopy, on the other hand, is associated with an annual health iii benefit of $1.4 million USD. LULC modifications can mitigate some fraction of...

Assessing the Potential of Land Use Modification to Mitigate Ambient NO2 and Its Consequences for Respiratory Health

“…Sites were chosen to capture the effect of roads, railroads and vegetation on ambient NO 2 .The average measured NO 2 in summer was 11 ppb, with observed values ranging from 4 to 23 ppb, while the average measured winter NO 2 was 13 ppb, with observed values ranging from 3 to 29 ppb. Additional details about the field campaign can be found in Rao et al [ 26 , 65 ].…”

Integrating Diverse Perspectives for Managing Neighborhood Trees and Urban Ecosystem Services in Portland, OR (US)

“…Second, provisioning UES for urban foraging of food and natural medicine [11]. Third, regulating UES, as local climate resilience that prevents urban heat islands [12], air quality that mitigates respiratory problems [13] and stormwater catchment that controls flood and water flow [14]. Fourth, cultural UES bring socio-ecological values through selfactualization, esteem and belonging [7], connection with biodiversity and personalized ecology [15].…”