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Bradley A, Croes BE, Harkins C, McDonald BC, de Gouw JA. Air Pollution Inequality in the Denver Metroplex and its Relationship to Historical Redlining. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:4226-4236. [PMID: 38380822 PMCID: PMC10919081 DOI: 10.1021/acs.est.3c03230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 01/30/2024] [Accepted: 01/31/2024] [Indexed: 02/22/2024]
Abstract
Prior studies have shown that people of color (POC) in the United States are exposed to higher levels of pollution than non-Hispanic White people. We show that the city of Denver, Colorado, displays similar race- and ethnicity-based air pollution disparities by using a combination of high-resolution satellite data, air pollution modeling, historical demographic information, and areal apportionment techniques. TROPOMI NO2 columns and modeled PM2.5 concentrations from 2019 are higher in communities subject to redlining. We calculated and compared Spearman coefficients for pollutants and race at the census tract level for every city that underwent redlining to contextualize the disparities in Denver. We find that the location of polluting infrastructure leads to higher populations of POC living near point sources, including 40% higher Hispanic and Latino populations. This influences pollution distribution, with annual average PM2.5 surface concentrations of 6.5 μg m-3 in census tracts with 0-5% Hispanic and Latino populations and 7.5 μg m-3 in census tracts with 60-65% Hispanic and Latino populations. Traffic analysis and emission inventory data show that POC are more likely to live near busy highways. Unequal spatial distribution of pollution sources and POC have allowed for pollution disparities to persist despite attempts by the city to rectify them. Finally, we identify the core causes of the pollution disparities to provide direction for remediation.
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Affiliation(s)
- Alexander
C. Bradley
- University
of Colorado Boulder, Boulder, Colorado 80309, United States
- Cooperative
Institute for Research in Environmental Sciences, Boulder, Colorado 80309, United States
| | - Bart E. Croes
- Cooperative
Institute for Research in Environmental Sciences, Boulder, Colorado 80309, United States
| | - Colin Harkins
- Cooperative
Institute for Research in Environmental Sciences, Boulder, Colorado 80309, United States
- Chemical
Sciences Laboratory, National Oceanic and
Atmospheric Administration, Boulder, Colorado 80305, United States
| | - Brian C. McDonald
- Chemical
Sciences Laboratory, National Oceanic and
Atmospheric Administration, Boulder, Colorado 80305, United States
| | - Joost A. de Gouw
- University
of Colorado Boulder, Boulder, Colorado 80309, United States
- Cooperative
Institute for Research in Environmental Sciences, Boulder, Colorado 80309, United States
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He L, You Y, Zheng X, Zhang S, Li Z, Zhang Z, Wu Y, Hao J. The impacts from cold start and road grade on real-world emissions and fuel consumption of gasoline, diesel and hybrid-electric light-duty passenger vehicles. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158045. [PMID: 35981594 DOI: 10.1016/j.scitotenv.2022.158045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 07/19/2022] [Accepted: 08/11/2022] [Indexed: 06/15/2023]
Abstract
Progressively stringent regulations regarding vehicle emissions and fuel economy have spurred technology diversification in light-duty passenger vehicles (LDPVs). To assess the real-world emissions and fuel economy performances of hybrid electric vehicles (HEVs) compared to conventional internal combustion engine (ICE) vehicles, on-road measurements of ten gasoline, four diesel and six full hybrid LDPVs were performed using portable emissions measurement systems (PEMS) in Macao, China. The hot-running emission results indicate that the high emission risks of gasoline vehicles are associated with high mileage and old model years. Diesel vehicles are found to be the highest pollutant emitters in this study due to the intentional removal of aftertreatment systems. Under hot-running conditions, HEVs, as expected, could achieve carbon-reduction benefits of approximately 30 % (i.e., lower CO2 emissions and fuel consumption) compared to their conventional gasoline counterparts, while no measurable reduction in pollutant emissions was observed except in NOX (~70 % reduction). In contrast, the cold-start extra emissions (CSEEs) of CO2 reached 120-364 g/start for these HEVs, even exceeding the maximum values of conventional gasoline vehicles. However, the higher CO2 CSEEs of HEVs can be far offset by their hot-running emission reduction benefits. For tailpipe pollutants, the CSEEs of the HEVs were reduced by 21 %-68 % on average in comparison to those of conventional gasoline vehicles. Furthermore, strong correlations (R2 values of 0.69-0.89) between the road grades and relative emissions were observed. These results can provide necessary information regarding the improvement of future LDPV emission models and inventories.
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Affiliation(s)
- Liqiang He
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China
| | - Yan You
- National Observation and Research Station of Coastal Ecological Environments in Macao, Macao Environmental Research Institute, Macau University of Science and Technology, Macao SAR 999078, China
| | - Xuan Zheng
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China
| | - Shaojun Zhang
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China; Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China
| | - Zhenhua Li
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China
| | - Zikai Zhang
- National Observation and Research Station of Coastal Ecological Environments in Macao, Macao Environmental Research Institute, Macau University of Science and Technology, Macao SAR 999078, China
| | - Ye Wu
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China; Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China.
| | - Jiming Hao
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing 100084, China; State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China; Beijing Laboratory of Environmental Frontier Technologies, School of Environment, Tsinghua University, Beijing 100084, China
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Revisiting Total Particle Number Measurements for Vehicle Exhaust Regulations. ATMOSPHERE 2022. [DOI: 10.3390/atmos13020155] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Road transport significantly contributes to air pollution in cities. Emission regulations have led to significantly reduced emissions in modern vehicles. Particle emissions are controlled by a particulate matter (PM) mass and a solid particle number (SPN) limit. There are concerns that the SPN limit does not effectively control all relevant particulate species and there are instances of semi-volatile particle emissions that are order of magnitudes higher than the SPN emission levels. This overview discusses whether a new metric (total particles, i.e., solids and volatiles) should be introduced for the effective regulation of vehicle emissions. Initially, it summarizes recent findings on the contribution of road transport to particle number concentration levels in cities. Then, both solid and total particle emission levels from modern vehicles are presented and the adverse health effects of solid and volatile particles are briefly discussed. Finally, the open issues regarding an appropriate methodology (sampling and instrumentation) in order to achieve representative and reproducible results are summarized. The main finding of this overview is that, even though total particle sampling and quantification is feasible, details for its realization in a regulatory context are lacking. It is important to define the methodology details (sampling and dilution, measurement instrumentation, relevant sizes, etc.) and conduct inter-laboratory exercises to determine the reproducibility of a proposed method. It is also necessary to monitor the vehicle emissions according to the new method to understand current and possible future levels. With better understanding of the instances of formation of nucleation mode particles it will be possible to identify its culprits (e.g., fuel, lubricant, combustion, or aftertreatment operation). Then the appropriate solutions can be enforced and the right decisions can be taken on the need for new regulatory initiatives, for example the addition of total particles in the tailpipe, decrease of specific organic precursors, better control of inorganic precursors (e.g., NH3, SOx), or revision of fuel and lubricant specifications.
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Tan Y, Yoon S, Ruehl CR, Herner J, Henderick P, Montes T, Latt J, Lee A, Florea E, Lemieux S, Robertson W, Hu S, Huai T. Assessment of In-Use NOx Emissions from Heavy-Duty Diesel Vehicles Equipped with Selective Catalytic Reduction Systems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:13657-13665. [PMID: 34591445 DOI: 10.1021/acs.est.1c03042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
This work evaluated the nitrogen oxide (NOx) emissions of 277 heavy-duty diesel vehicles (HDDVs) from three portable emission measurement system testing programs. HDDVs in these programs were properly maintained before emission testing, so the malfunction indicator lamp (MIL) was not illuminated. NOx emissions of some HDDVs were significantly higher than the certification standard even during hot operations where exhaust temperature was ideal for selective catalytic reduction to reduce NOx. For engines certified to the 0.20 g/bhp-hr NOx standard, hot operation NOx emissions increased with engine age at 0.081 ± 0.016 g/bhp-hr per year. The correlation between emissions and mileage was weak because six trucks showed extraordinarily high apparent emission increase rates reaching several multiples of the standard within the first 15,000 miles of operation. The overall annual increase in NOx emissions for the HDDVs in this study was two-thirds of what was observed in real-world emissions for HDDVs at the Caldecott Tunnel over the past decade. The vehicles at the Caldecott Tunnel would include those without proper maintenance, and the inclusion of these vehicles possibly explains the difference in the rate of emission increase. The results suggest that HDDVs need robust strategies to better control in-use NOx emissions.
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Affiliation(s)
- Yi Tan
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Seungju Yoon
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Chris R Ruehl
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Jorn Herner
- California Air Resources Board, 1001 I Street, Sacramento, California 95814, United States
| | - Paul Henderick
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Tom Montes
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Jenna Latt
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Abraham Lee
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Elena Florea
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Sharon Lemieux
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - William Robertson
- California Air Resources Board, 9500 Telstar Avenue, Ste. #2, El Monte, California 91731, United States
| | - Shaohua Hu
- California Air Resources Board, 8340 Ferguson Avenue, Sacramento, California 95828, United States
| | - Tao Huai
- California Air Resources Board, 8340 Ferguson Avenue, Sacramento, California 95828, United States
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