|M.Sc Thesis||Department of Civil and Environmental Engineering|
|Supervisor:||Assoc. Prof. Broday David|
|Full Thesis text|
Nitrogen oxides (Nitrogen dioxide (NO2) and nitrogen monoxide (NO) and particulate matter (PM) are prevalent urban air pollutants. They have been linked to respiratory symptoms, cardiac disease, and premature death. Vehicular transportation is a dominant source of urban NO emissions, which rapidly undergo photochemical oxidation to form NO2, the pollutant of concern for its health effects. Due to its short atmospheric life time, NO is often used as a marker for transportation related pollution when measured at road side. On the other hand, it is known that transportation contributes to PM concentrations, but the extent and size fraction is less well understood. Unlike NOx, PM has an atmospheric life span on the synoptic scale. PM may therefore stem from local or long range anthropogenic and biogenic activities, making the sources and composition more complex to understand. Proper characterization of local PM composition, size fraction, and source are necessary for exposure and epidemiology studies, and for public policy.
The main goal of this work is to characterize the contribution of vehicular transportation to NO, NO2, PM2.5 and PM10 concentrations in the Gush Dan and Haifa Metropolitan regions in Israel. A methodology is proposed based on analysis of air quality monitoring data. NO is used as a marker for vehicular traffic and juxtaposed with PM data on various spatial and temporal scales.
Highly resolved temporal patterns reveal a strong traffic signature in NOx concentrations and NO:NO2 ratios in both regions. NO2 concentrations at roadside (RS) sites often exceed national ambient air quality standards, especially at peak rush hours, the very hours people are most exposed to air pollution. Long-term (5 year) averages reveal a decline in NO in both regions, despite increased vehicle-km travelled.
We find PM to vary significantly on the intraurban spatial scale and on various temporal scales. A high correlation between the diurnal pattern of PM and NO was found in most locations. By studying a large sample of AQM stations over a long period of time, a correlation is detected between long term NO and PM concentrations over all stations. Despite a high background PM concentration, which confounds the ability to quantify the contribution of local sources to urban PM, the contribution of local vehicular transportation can be detected by an analysis of hourly and daily PM10 and PM2.5 averages, which indicate that heavy traffic may contribute up to ~20% of the observed PM.