Identifying Traffic-Related Air Pollution Hotspots in the Built Environment Objective
Preliminary Findings Significantly higher ultrafine particle concentrations were found in morning (9-10AM) compared to afternoon (3-4pm) shift measurements.
1
Spatially speaking, higher pollution concentrations occurred more frequently in the street canyon section of the route than in the lower buildings section.
Wind Flow
High emitting vehicles (HEV), typically old light duty vehicles or heavy duty trucks, were associated with higher spikes of pollution. Acceleration of long queues at major intersections may also contribute to larger vehicle plumes. This study characterizes the spatial and temporal distribution of ultrafine particles in the built microenvironment given traffic and meteorological conditions.
Problem
Prevailing southwesterly winds may suggest a trapping of concentrations on the leeward (downwind) side of tall buildings within the street canyon, but more information on surface street level winds and indoor concentrations is needed.
Air Pollution Levels: Morning vs. Afternoon
Given the passage of California’s SB 375 Sustainable Communities Strategy, smart growth policies may have unintended consequences of compact, transit-oriented development (TOD) disproportionately exposing pedestrians to localized concentrations of traffic-related air pollution.2 Specifically, ultrafine particles found heavily in vehicle exhaust are associated with adverse health outcomes including respiratory, cardiovascular, and fetal development issues. 3
Policy Recommendations Transit-oriented development designs should consider existing and projected contexts of the surrounding built-environment, traffic, and meteorological conditions. Vary building heights in dense developments to lessen street canyon effect. Orient buildings to facilitate air dispersion based on prevailing winds. Encourage traffic management strategies that avoid acceleration of long queues. Avoid placing developments that generate heavy foot traffic and outdoor pedestrian dwelling times in the morning (i.e. coffee shops) on the leeward (downwind) side of busy intersections. Place bus stops on the far-side (after crossing intersection) to reduce exposure to vehicle plumes due to acceleration from traffic lights. Design bus shelters that minimize trapping of air pollutants. Mindful green landscaping (i.e. street tree’s canopy size as carbon sink vs. concentrating pollution) that suits streetscape context. Mandate (not recommend) siting sensitive (i.e. school, hospital, residential) land uses 500ft away from major freeways. Use Cap and Trade proceeds to fund further research to inform SB 375’s smart growth strategies of environmental justice and public health implications.
Ultrafine particles (> 0.1 micrometers) can be absorbed into your lung and brain cells.4
Methods A mobile air monitoring platform was used to measure ultrafine particles on a 1second basis along a 3 mile-long transect in Downtown Los Angeles in April-July 2008 for a total of 12 runs and roughly 7,500 observations.
Air Pollution Spikes: Morning vs. Afternoon Complete Streets (Source: WalkSacramento.org) GIS Linear Referencing System (Sync by Lat/Long & Time Stamp)
Acknowledgements This master’s thesis is part of a larger Air Resources Board funded study. My capstone project was only made possible by the contributions from the following transdisciplinary research groups: UCLA’s Luskin Center for Innovation: Co-principal Investigator J.R. DeShazo, GIS Experts Norman Wong & Henry Howland, Statisticians Fanghua Li & Owens Heary, and Research Assistants Audrey Vinant-Tang, Warren Tan & Maverick Padilla
Street Canyon Low Buildings Source: Google Maps Mobile Monitoring Platform (Source: Air Resources Board)
UCLA’s Department of Atmospheric & Oceanic Sciences: Co-principal Investigator Suzanne Paulson, Doctoral Researchers Wonsik Choi & Rodrigo Seguel, and Master’s Candidates Karen Bunavage & Dilhara Ranasinghe
Broadway Transect (Source: ArcScene, LAR-IAC)
Boxplots
UCLA’s School of Public Health: Co-principal Investigator Arthur Winer
West Buildings Concentrations
Average Air Pollution Levels: Intersections (20m Buffer) Intersection Concentrations
UC Riverside’s Department of Mechanical Engineering: Co-principal Investigator Akula Venkatram, Doctoral Researchers Nico Schultz & Si Tan I would also like to thank my Capstone Instructor, Leo Estrada, and my Thesis Committee Members Doug Houston and Paul Ong.
References [1] Air Resources Board awards grant to UCLA. (2013, Spring). Luskin Center Impact, 11. Retrieved from http://issuu.com/uclaluskincenter/docs/impact_2013 [2] Ewing, R. & Cervero, R. (2001). Travel and the built environment - synthesis. Transportation Research Record, 1780, 87-106. [3] Houston, D., Krudysz, M., & Winer, A. (2008) Diesel truck traffic in port-adjacent lowincome and minority communities: Environmental justice implications of near-roadway land use conflicts. Transportation Research Record: Journal of the Transportation Research Board, 2076, 38-46. doi: 10.3141/2067-05 [4] Bruning, Thomas et al. (2006). Assessment of the health effects of toner particles on people in the workplace. BG Research Institute for Occupational Medicine. Retrieved from http://www.tesa-clean-air.com/eng/fine_dust_particles
East Buildings Concentrations
Lisa Wu w.lisa068@gmail.com
Master of Urban and Regional Planning University of California, Los Angeles
Capstone Project: Master’s Thesis Thesis Committee Chair: J.R. DeShazo