conference paper
published journal article
Soil-based risk assessment shows a U.S. city to exceed federal acceptable risk levels for both non-carcinogenic and carcinogenic health outcomes in many areas, with total risk and soil contamination being correlated with socioeconomic factors. , (1) Background: exposure to heavy metals is associated with adverse health effects and disproportionately impacts low-income communities and communities of color. We carried out a community-based participatory research study to examine the distribution of heavy metal concentrations in the soil and social vulnerabilities to soil heavy metal exposures across Census tracts in Santa Ana, CA. (2) Methods: soil samples ( n = 1528) of eight heavy metals including lead (Pb), arsenic (As), manganese (Mn), chromium (Cr), nickel (Ni), copper (Cu), cadmium (Cd), and zinc (Zn) were collected in 2018 across Santa Ana, CA, at a high spatial resolution and analyzed using XRF analysis. Metal concentrations were mapped out and American Community Survey data was utilized to assess metals throughout Census tracts in terms of social and economic variables. Risk assessment was conducted to evaluate carcinogenic and non-carcinogenic risk. (3) Results: concentrations of soil metals varied according to landuse type and socioeconomic factors. Census tracts where the median household income was under $50 000 had 390%, 92.9%, 56.6%, and 54.3% higher Pb, Zn, Cd, and As concentrations compared to high-income counterparts. All Census tracts in Santa Ana showed hazard index >1, implying the potential for non-carcinogenic health effects, and nearly all Census tracts showed a cancer risk above 10 −4 , implying a greater than acceptable risk. Risk was predominantly driven by childhood exposure. (4) Conclusions: findings inform initiatives related to environmental justice and highlight subpopulations at elevated risk of heavy metal exposure, in turn underscoring the need for community-driven recommendations for policies and other actions to remediate soil contamination and protect the health of residents.
policy brief
In December 2018, the California Air Resources Board (CARB) approved the Innovative Clean Transit regulation, which is designed to transition the state to all-electric bus fleets by 2040. To comply with this first-of its-kind regulation, transit agencies have two alternatives: battery electric buses (BEBs) and hydrogen fuel cell electric buses (FCEBs). These options vary in energy requirements, overall effectiveness in reducing different emission types, associated life cycle costs (including disposal of the bus), and ability to meet operating needs of transit agencies. To support transit agencies and decision makers transition to cleaner bus technologies, researchers at UC Irvine developed a life cycle-based analysis (LCA) tool to estimate the potential costs and benefits of switching to BEBs and FCEBs compared to conventional buses. The LCA tool was tested on the Orange County Transportation Authority (OCTA) to better understand the environmental impacts and cost constraints.
published journal article
conference paper
This study developed a methodology to create detailed vehicle travel information through a vehicle reidentification system (REID) based on inductive vehicle signatures. A novel feature of this study is to utilize point and section measures, which are outputs of REID, for deriving individual vehicle speed profiles that can be further used to estimate vehicle emissions. The proposed methodology consists of three components. First, characteristics of vehicle maneuvers are identified thru clustering techniques. Second, speed profiles are constructed using a genetically optimized autoregressive model. Third, vehicle emissions are estimated using the Motor Vehicle Emission Simulator (MOVES) emissions model. Next Generation Simulation (NGSIM) data collected from the US 101 in Los Angeles, CA was used for model development and performance evaluation. Results revealed that less than 4% error of estimated emissions was achieved by the proposed method, which is promising for field implementation. It is expected that the outcome of this study will be valuable in developing more efficient and useful traffic surveillance systems for vehicle emissions monitoring.
published journal article
