Assessing the relationship among urban trees, nitrogen dioxide, and respiratory health

Integrating High-Resolution Datasets to Target Mitigation Efforts for Improving Air Quality and Public Health in Urban Neighborhoods

“…Based on the CIDS and a highly-resolved NO 2 surface [37] (Figure 2), we estimated that ~330,500 people (18% of the Portland Metro population) are exposed to the worst quintile of NO 2 pollution (13–24 ppb). Census Geography rasters were measured in the same manner by overlaying the area of interest over a rasterized choropleth of population density for both CBG and Census Tracts and calculating population values for only those specific pixels.…”

“…We used the NO 2 model developed by Rao et al (2014) [37] (Equation (3)) for the Portland Metro area to assess air quality. Rao et al were able to explain 80% of the variation in NO 2 using a model that employed variables such as annual average daily traffic (AADT) and tree cover.…”

“…For more details on the field campaign and model development, please see Rao et al (2014) [37]. As can be seen from the model, each hectare of tree cover within a 400 m radius of a site is associated with a 0.6 ppb reduction in NO 2 , holding all other variables constant.…”

A case study using remote sensing data to compare biophysical properties of a forest and an urban area in Northern Alabama, USA

“…The difference in air quality might be partially related to fossil fuel burning, additional pollution sources located in the urban area, and the "filtering" effects of the forest area. NO 2 is considered to be a strong marker for anthropogenic air pollution, as biogenic volatile organic compounds emitted by trees react with urban NO x emissions to produce aerosols (a component of PM2.5) and ozone (Rao, George, Rosenstiel, Shandas, & Dinno, 2014). In this study, there were on average 9.4 kg less SO 2 (0.5 g per ha) and 40.9 kg (2.21 g per ha) less NO 2 in the forest than in the urban area each day.…”

Downwind particulate matters: Regulatory implications of secondary aerosol formation from the interaction of nitrogen oxides and tree emissions

“…Trees are also planted to assist with superfund site cleanup (Pulford and Watson, 2003;Van Aken, 2008). A recent article (Rao et al, 2014) finds that tree cover in Portland, Oregon contributes to a reduction of NO x . Our results contribute to the understanding of the mechanism associated with NO x removal -namely, it is possible that biogenic VOCs react with NO x to effectively remove it from the air, but in the process may produce additional PM 2.5 .…”