Particulate Emission Rates from In-Use High-Emitting Vehicles Recruited in Orange County, California (original) (raw)
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Atmospheric Environment, 2004
This research assessed in-vehicle exposures to black carbon (BC) as an indicator of diesel particulate matter (DPM) exposures. Approximately 50 h of real-time Aethalometer BC measurements were made inside vehicles driven on freeway and arterial loops in Los Angeles and Sacramento. Video tapes of the driver's view were transcribed to record the traffic conditions, vehicles followed, and vehicle occupant observations, and these results were tested for their associations with BC concentration. In-vehicle BC concentrations were highest when directly following diesel-powered vehicles, particularly those with low exhaust pipe locations. The lowest BC concentrations were observed while following gasoline-powered passenger cars, on average no different than not following any vehicle. Because diesel vehicles were over-sampled in the field study, results were not representative of real-world driving. To calculate representative exposures, in-vehicle BC concentrations were grouped by the type of vehicle followed, for each road type and congestion level. These groupings were then re-sampled stochastically, in proportion to the fraction of statewide vehicle miles traveled (VMT) under each of those conditions. The approximately 6% of time spent following diesel vehicles led to 23% of the in-vehicle BC exposure, while the remaining exposure was due to elevated roadway BC concentrations. In-vehicle BC exposures averaged 6 mg m À3 in Los Angeles and the Bay Area, the regions with the highest congestion and the majority of the state's VMT. The statewide average in-vehicle BC exposure was 4 mg m À3 , corresponding to DPM concentrations of 7-23 mg m À3 , depending on the Aethalometer response to elemental carbon (EC) and the EC fraction of the DPM. In-vehicle contributions to overall DPM exposures ranged from approximately 30% to 55% of total DPM exposure on a statewide population basis. Thus, although time spent in vehicles was only 1.5 h day À1 on average, vehicles may be the most important microenvironment for overall DPM exposure. r
Tobacco Control, 2012
Context Exposure to secondhand smoke (SHS) has been reduced in the USA by banning smoking in public places. These restrictions have not had the same effect on children's exposure to SHS as adults suggesting that children are exposed to SHS in locations not covered by bans, such as private homes and cars. Objectives Assess exposure to SHS in the backseat of a stationary vehicle where a child would sit, quantify exposures to fine particulates (PM2.5), polycyclic aromatic hydrocarbons (PAH), carbon monoxide (CO) and nicotine. Estimate the impact on a child's mean daily exposure to PM2.5. Methods SHS exposures in stationary vehicles with two different window configurations were monitored. A volunteer smoked three cigarettes in a one-hour period for twenty-two experiments. PM2.5, CO, nicotine and PAH where measured in the backseat of the vehicle. 16 PAH compounds were measured for in gas and particle phases as well as real-time particle phase concentrations. Results The mean PAH concentration, 1325.1 ng/m 3 , was larger than concentrations measured in bars and restaurants were smoking is banned in many countries. We estimate that a child spending only ten minutes in the car with a smoker at the mean PM2.5 concentration measured in the first window configuration −1697 mg/m 3will cause a 30% increase to the daily mean PM2.5 personal average of a child. Conclusions Estimates made using the measured data and previously reported PM2.5 daily mean concentrations for children in California showing that even short exposure periods are capable of creating large exposure to smoke.
Motor Vehicle Contributions to Ambient PM10 and PM2.5 at Selected Urban Areas in the USA
Environmental Monitoring and Assessment, 2006
A source apportionment study was carried out to estimate the contribution of motor vehicles to ambient particulate matter (PM) in selected urban areas in the USA. Measurements were performed at seven locations during the period September 7, 2000 through March 9, 2001. Measurements included integrated PM 2.5 and PM 10 concentrations and polycyclic aromatic hydrocarbons (PAHs). Ambient PM 2.5 and PM 10 were apportioned to their local sources using the chemical mass balance (CMB) receptor model and compared with results obtained using scanning electron microscopy (SEM). Results indicate that PM 2.5 components were mainly from combustion sources, including motor vehicles, and secondary species (nitrates and sulfates). PM 10 consisted mainly of geological material, in addition to emissions from combustion sources. The fractional contributions of motor vehicles to ambient PM were estimated to be in the range from 20 to 76% and from 35 to 92% for PM 2.5 and PM 10 , respectively.
Evaluation of Heavy- and Medium-Duty On-Road Vehicle Emissions in California’s South Coast Air Basin
Environmental Science & Technology
Emission measurements were collected from heavyduty (HDVs) and medium-duty vehicles (MDVs) at the Peralta weigh station long-term measurement site near Anaheim, CA, in 2017. Two Fuel Efficiency Automobile Test units sampled elevated and ground-level exhaust vehicles totaling 2 315 measurements. HDVs (1844 measurements) exhibited historical reductions in fuel specific oxides of nitrogen (NO x) from the 2008 measurements (55%) with increased use of exhaust gas recirculation and selective catalytic reduction systems. However, as these technologies have aged, the in-use benefits have declined. Infrared % opacity measurements of tailpipe soot decreased 14% since 2012 with increased diesel particulate filter (DPF) use, DPF longevity, and fleet turnover. Sixty-three percent of the HDV fleet in 2017 was chassis model year 2011+ compared to only 12% in 2012. The observed MDV fleet (471 measurements) was 1.4 years older than the HDV fleet with average NO x 14% higher. A significant reduction in MDV NO x occurred ∼2 model years prior to similar HDV reductions (2014 versus 2016 chassis model year). MDV chassis model years 2014+ were able to meet their corresponding NO x laboratory certification standards in-use, whereas HDVs remain slightly above this threshold. Similar MDV NO x emission trends were also observed in data previously collected in Chicago, IL.
Journal of The Air & Waste Management Association, 2007
The U.S. Department of Energy Gasoline/Diesel PM Split Study examined the sources of uncertainties in using an organic compound-based chemical mass balance receptor model to quantify the contributions of spark-ignition (SI) and compression-ignition (CI) engine exhaust to ambient fine particulate matter (PM 2.5 ). This paper presents the chemical composition profiles of SI and CI engine exhaust from the vehicle-testing portion of the study. Chemical analysis of source samples consisted of gravimetric mass, elements, ions, organic carbon (OC), and elemental carbon (EC) by the Interagency Monitoring of Protected Visual Environments (IMPROVE) and Speciation Trends Network (STN) thermal/optical methods, polycyclic aromatic hydrocarbons (PAHs), hopanes, steranes, alkanes, and polar organic compounds. More than half of the mass
During the spring and summer of 2000, 2001, and 2002, gaseous and particulate matter (PM) fuel-based emission factors for approximately 150,000 low-tailpipe, individual vehicles in the Las Vegas, NV, area were measured via on-road remote sensing. For the gaseous pollutants (carbon monoxide, hydrocarbons, and nitrogen oxide), a commercial vehicle emissions remote sensing system (VERSS) was used. The PM emissions were determined using a Lidar-based VERSS. Emission distributions and their shapes were analyzed and compared with previous studies. The large skewness of the distributions is evident for both gaseous pollutants and PM and has important implications for emission reduction policies, because the majority of emissions are attributed to a small fraction of vehicles. Results of this Las Vegas study and studies at other geographical locations were compared. The gaseous pollutants were found to be close to those measured by VERSS in other U.S. cities. The PM emission factors for spark ignition and diesel vehicles are in the range of previous tunnel and dynamometer studies.
Journal of the Air & Waste Management Association, 2004
During the spring and summer of 2000, 2001, and 2002, gaseous and particulate matter (PM) fuel-based emission factors for ϳ150,000 low-tailpipe, individual vehicles in the Las Vegas, NV, area were measured via on-road remote sensing. For the gaseous pollutants (carbon monoxide, hydrocarbons, and nitrogen oxide), a commercial vehicle emissions remote sensing system (VERSS) was used. The PM emissions were determined using a Lidar-based VERSS. Emission distributions and their shapes were analyzed and compared with previous studies. The large skewness of the distributions is evident for both gaseous pollutants and PM and has important implications for emission reduction policies, because the majority of emissions are attributed to a small fraction of vehicles. Results of this Las Vegas study and studies at other geographical locations were compared. The gaseous pollutants were found to be close to those measured by VERSS in other U.S. cities. The PM emission factors for spark ignition and diesel vehicles are in the range of previous tunnel and dynamometer studies.
Ambient and Emission Trends of Toxic Air Contaminants in California
Environmental Science & Technology, 2015
After initiating a toxic air contaminant (TAC) identification and control program in 1984, the California Air Resources Board adopted regulations to reduce TAC emissions from cars, trucks, stationary sources, and consumer products. This study quantifies ambient concentration and emission trends for the period 1990–2012 for seven TACs that are responsible for most of the known cancer risk associated with airborne exposure in California. Of these seven, diesel particulate matter (DPM) is the most important; however DPM is not measured directly. Based on a novel surrogate method, DPM concentrations declined 68%, even though the state's population increased 31%, diesel vehicle-miles-traveled increased 81%, and the gross state product (GSP) increased 74%. Based on monitoring data, concentrations of benzene, 1,3-butadiene, perchloroethylene, and hexavalent chromium declined 88–94%. Also, the ambient and emissions trends for each of these four TACs were similar. Furthermore, these declines generally occurred earlier in California than elsewhere. However, formaldehyde and acetaldehyde, which are formed in the air photochemically from volatile organic compounds (VOCs), declined only 20–21%. The collective cancer risk from exposure to these seven reviewed TACs declined 76%. Significant reduction in cancer risk to California residents from implementation of air toxics controls (especially for DPM) is expected to continue.
WIT Transactions on the Built Environment, 2013
While airborne particulate matter (PM) has been associated with numerous health effects, very few studies have extensively examined the changes in exposure to PM and its health-relevant constituents, which occur in major metropolitan areas over time (e.g., 5-10 years). This study addresses changes in the PM2.5 concentration and elemental composition between two monitoring campaigns (2002-2005 and 2010-2011) carried out in the Cincinnati (Ohio, USA) metropolitan area. The area is known for high traffic volume, largely represented by diesel-powered trucks on regional freeways. The air monitoring was conducted at four sites. Through an analysis of variance comparison, differences between the two data sets were assessed for PM2.5, ten selected elements, elemental carbon (EC), organic carbon (OC), and EC/OC (a surrogate of the diesel exhaust contribution). Measured at the site that was previously found to exhibit the highest level of EC attributable to traffic, most of traffic related elements and the EC/OC ratio showed statistically significant decreases in concentration over time; however, the decrease became of borderline significance when wind variables were incorporated into the model. No major differences between data generated in the two campaigns were observed at the other monitoring stations with respect to EC/OC. Although the positive trends identified in this study (e.g., decrease in PM2.5, Ti, V, Mn, Fe, Zn, Br, and Pb, EC, OC, and EC/OC) may become sustainable in the future, no strong evidence was found that the air quality control and engine exhaust control policies implemented between 2005 and 2010 have produced significant changes in traffic air pollution levels in the entire metropolitan area. The PM monitoring