California Air Resources Board

Scope of Work

Background

Traffic-related air pollution (TRAP) has been a focus of CARB rules and programs due to the many health effects associated with vehicle pollution and the impacts of these sources on the air quality in California. However, traffic pollution includes pollution from both tailpipe emissions as well as non-tailpipe emissions (NEE). NEE can be a product of different sources including brake wear, tire and road wear, clutch wear and road dust resuspension. The NEE sources can be difficult to measure [1]. However, with increasingly stringent standards for exhaust emissions, the non-exhaust fraction has become a relatively greater proportion of traffic emissions. Model predictions suggest that traffic-related emissions of both PM2.5 and PM10 will eventually be dominated by non-exhaust sources, making this an important source of near roadway exposures. This is an active area of research, but the health impacts of brake and tire wear, particularly in ambient air, have not been well studied. A recent CARB funded study[2] examined the health impacts of metals in particulate matter associated with brake and tire wear in Los Angeles and found adverse birth outcomes associated with metals from brake (barium) and tire wear (zinc) emissions. Particles were also found to be more toxic in disadvantaged neighborhoods due to the ability of the particles to produce higher levels of oxidative stress [3]. However, metals associated with brake and tire wear can also be associated with other sources and relying on metals alone as markers for brake and tire wear can lead to high uncertainties in the exposure assessment.

Most of the studies on brake and tire wear have concentrated on examining the chemical components of brake and tire wear directly by collecting samples from dynamometers, for example. The Vehicle Emissions Research Program of CARB has developed external research contracts and is performing in-house studies to better characterize individual non-exhaust sources including brake and tire wear. This program also collaborates with various other agencies and organizations to help understand the different chemical components and relative contribution of non-exhaust emissions to roadway emissions. Program agencies include the Health Effects Institute, Caltrans, the U.S. Environmental Protection Agency, as well as California Universities, including UC Irvine and UC Riverside. Through this research, CARB is developing updated information for CARB's EMFAC model and improved understanding of the most important factors affecting the emissions from non-exhaust sources. This program will help to develop an emission inventory to better understand the impact of this pollution source on overburdened communities living near roadways.  However, there is also a need to understand the effects of brake and tire wear on health and on ambient air. This need has been recognized by CARB and other organizations including the South Coast Air Quality Management District. MATES VI, funded by the South Coast district will include an examination of brake and tire wear in ambient air for the first time in the MATES program in the South Coast Air Basin and the Coachella Valley.

This proposed CARB funded study will interact and coordinate with ongoing studies to provide a regional assessment of the health impacts of brake and tire wear from on road sources and will support the need to reduce this major pollution source. The study will be focused on a region with overburdened communities with high exposures to traffic pollution and NEE possibly in the San Joaquin Valley or another understudied area. The proposed study will need to develop methods to identify and measure exposures to brake and tire wear at the regional level in ambient air with a reasonable degree of uncertainty. The study will coordinate and build upon ongoing CARB funded studies and the efforts of other agencies and organizations including the MATES VI program in developing these methods. While there is no established method for determining levels of brake and tire wear in ambient air, a number of different methods that combine ambient measurements and models to estimate brake and tire wear emission rates or concentrations can be used to determine ambient exposure to brake and tire wear.

The proposed study will be focused on a region with overburdened communities with exposures to high traffic volumes and more exposure to NEE.  Overburdened communities are impacted by a combination of economic, health, and environmental stressors and have long suffered from a lack of resources and support. These stressors include poverty, air and water pollution, as well as high incidences of asthma and heart disease in the residents. These communities often have a long history of structural racism and siting of major traffic corridors near these communities resulting in greater exposures. The communities in the region selected for the study will not only be located near roadways with higher traffic volume but will also be located near features that result in higher NEE exposures such as entrance and exit ramps and busy intersections. Areas such as the San Joaquin Valley could be a priority since our previous study was conducted in the Los Angeles area. Health data will be used to evaluate the association between NEE exposures and health outcomes related to respiratory and cardiovascular impacts. These will include preexisting health databases such as the numbers of hospitalizations or emergency room visits. Results will help CARB to understand the impacts of brake and tire wear emissions on health and particle toxicity. It will also help CARB understand exposure disparities for communities exposed to higher levels of NEE.

Objective

The objective of this study is to conduct a regional assessment of the exposure and health risks for brake and tire wear in PM2.5 and PM10. The study will be focused on a region with overburdened communities, possibly in the San Joaquin Valley, with high exposures to NEE pollution. The findings of this project will enhance the understanding of how NEE particles affect cardiovascular and respiratory human health in a region with overburdened communities. It will increase the understanding of the impacts of brake and tire wear particles on outdoor air and their role in particle toxicity and provide evidence for government agencies of the need to reduce such exposures through policies and programs.

Scope of Work

The project will assess NEE exposure and health risks focused on a region with overburdened communities with high exposures to NEE from traffic, possibly in the San Joaquin Valley.  A workplan will be developed to determine the research approach and methods to be used in the study. Methods will be used to identify exposures to brake and tire wear emissions and to relate those exposures to health effects, building on ongoing studies and completed studies by CARB and other organizations. Additional information will be provided using a sampling campaign in the region. An analysis of oxidative stress will be used to explore if brake and tire wear exposures are driving higher oxidative stress in particle exposure in disadvantaged communities. Health data will be used to evaluate the NEE exposures for health outcomes such as cardiovascular and respiratory impacts across the region and in overburdened communities.

Proposed Project Tasks and corresponding deliverables

Task 1:Literature review

The investigators will conduct a literature review on brake and tire wear particles and their contribution to adverse health effects as well as methods used to measure and model brake and tire wear. This literature review will provide the background of the current science of the health effects of non-exhaust emissions and will build on the previous review from CARB funded study 17RD012 and other recent research. The study can use the information from this literature review to compare and develop the methods for the exposure assessment and to compare the health results seen in previous studies to NEE with the current study.

Task 1 Deliverable: A completed literature review with the current scientific information on the health effects of non-exhaust emissions related to brake and tire wear particles and the methods used in exposure development.

Task 2: Development of a Workplan for the Study

The investigators will develop a work plan in consultation with CARB staff by the end of the second quarter of the contract for the tasks to be accomplished in the study. The investigators will invite input from the Technical Advisory Group before the workplan is finalized. The workplan will include the following:

• The region of study and how the region fits the objectives of this contract
• Plans for convening a Technical Advisory Group including community and academic representatives, and who will be included in the TAC.
• The methods selected for exposure modeling for brake and tire wear and the modeling tools used to produce an exposure map for the region (Task 3) as well as limitations of those methods.
• PM 2.5 and PM 10 monitoring methods, locations, and duration of the sampling that represent the study region as well as the PM sizes to be sampled at each location.
• Methods for the chemical speciation and analysis of the samples, including analysis of oxidative stress (Task 4).
• The health analysis approaches and methods to be used for linking health outcomes and oxidative stress to NEE exposure for the region and overburdened communities (Task 6), including the health outcomes and datasets to be used (Task 5).
• A plan and methods to compare exposures and health impacts in over-burdened communities to average exposures and health impacts.
• The plan will evaluate how and what is needed for community outreach on the study.

Task 2 Deliverables: A complete workplan for the study will be developed in consultation with CARB staff and with input from the Technical Advisory Group by the end of Quarter 2 to include the study design and all aspects of this study including the components listed above.

Task 3 Regional exposure assessment and monitoring campaign for PM2.5 and PM10 linked to brake and tire wear emissions

The researchers will determine the sampling and modeling methods to characterize ambient exposure levels for PM2.5 and PM10 associated with brake and tire wear. While there is no established method to determine brake and tire wear in community air, a number of methods have been used in other brake and tire wear studies. These methods include positive matrix factorization source apportionment of oxidative potential which was used in a previously funded CARB study[4]. By coordinating and building upon other completed and ongoing efforts a method should be developed to complete an exposure profile with an uncertainty of less than 30%. The investigators should be able to assure that the methods developed will be able to determine the exposures to brake and tire wear across the region of study and link the exposures to health data. The investigators should also list and discuss all the limitations of the exposure assessment.

A monitoring campaign will be used to provide needed information for the exposure modeling in the selected region of study. The number of samples collected should be adequate to model the exposure profile for the region of study and should be conducted over at least two seasons, summer and winter, to account for meteorological effects. The sampling locations should be across the region to be studied to be able to develop a mapped regional exposure layer. To select monitoring locations, the previous CARB study[5]developed a multi-criteria selection method that included variables likely to influence the spatial distribution of brake and tire wear such as intersection density, traffic density, and slope gradients. This same selection method could be used in this proposed study to select monitoring locations. Alternatively, sampling can be conducted near roadways and in the communities in the region of study to see the pattern of distribution of the brake and tire wear particles.

Investigators will use data analysis and modeling to differentiate NEE from tailpipe emissions and to produce an exposure profile at fine scale resolution for NEE emissions in the region. A previously funded CARB study used metals as tracers [6] but the metals have sources other than brake and tire wear and this method may result in higher uncertainty. A more complete analysis based on the full assessment of the elements, including but not limited to metals[7], in the ambient samples may be more useful[8]. Chemical profiles of the samples from the sampling campaign could be compared to chemical profiles of known brake and tire wear samples, provided from other CARB funded studies, and then be used to determine the distribution of brake and tire wear using source apportionment techniques. Analysis of the gas components of tire wear could be supplied from another CARB funded study and used in the source apportionment. Techniques could include positive matrix factorization.

Task 3 Deliverable: Development of an exposure model for the exposures to brake and tire wear in PM2.5 and PM10 particles in the study region to produce an exposure profile for the region at a fine scale resolution.

Task 4: Exposure analysis for oxidative stress levels

Investigators will conduct an analysis of oxidative stress levels to explore if brake and tire wear components are driving higher oxidative stress in particle exposures in overburdened communities. Investigators could use the US Environmental Protection Agency’s positive matrix factorization (PMF) source apportionment model version 5.0 to identify major sources and quantify their relative contribution to the volume normalized oxidative potential of OH and dithiothreitol (DTT) assay. The results in the previous study suggested that the OH assay may be better at predicting particle-induced adverse health outcomes than the DTT assay or PM2.5 mass for the aerosol sources present in this study ^[9]. Markers of oxidative stress in the current study should be linked to the exposure model used for brake and tire wear in the overburdened communities in the region of the study to be able to study the possible link between the oxidative stress levels and exposure levels of brake and tire wear.

Task 4 Deliverable: Oxidative stress levels of the particles will be linked to the exposure profiles to see if brake and tire wear exposures are associated with oxidative stress levels across the region and in overburdened communities. The result of this analysis will be an oxidative stress profile for the region.

Task 5: Identify and secure health datasets to be linked to exposure data

The researchers will identify health outcomes to be evaluated, including respiratory and cardiovascular hospitalizations, emergency department visits, or other health outcomes, and secure needed health datasets. Sources of data could include the California Department of Health Care Access and Information. The health outcome data needs to be in a resolution to pair with the exposure data to identify NEE related health impacts.

Task 5 Deliverable: Development of a health database for the same region covered by the exposure assessment for the health impact analysis.

Task 6: Analysis of health effects of NEE for the region and overburdened communities

The researchers will use appropriate statistical analysis methods to define the association between the regional NEE exposure profile and the oxidative stress profile developed in Task 3 and 4 and the health outcomes selected in Task 5. If possible, the investigators will quantify the association and produce dose response functions for the region and for overburdened communities in the region.

Task 6 Deliverable: The investigators will produce quantified results for the health impacts of NEE in the region and overburdened communities. If possible, the researchers will develop dose-response relationships of exposure to brake and tire wear and oxidative stress associated with brake and tire wear and health impacts (including cardiovascular and respiratory disease outcomes) in the region and overburdened communities.

Task 7: Technical Advisory Group

A technical advisory group will be developed to assist in providing additional expertise. The advisors will be composed of 6 to 8 individuals with half of the group being community representatives and half of the group being academic experts on brake and tire wear research to help provide advice on the study design. The group will meet at the beginning of the project to review and offer advice on the methodology to be used, including the exposure assessment and the health analysis and the development of the workplan. The group will meet again later in the project to discuss and offer advice on the research findings for the study.

For community engagement efforts including meetings with the TAC, the contractor must co-create meeting materials, including presentation slides, flyers, prompts and speaking notes with CARB staff. The contractor will work with CARB to understand policies and agree to accurately represent those policies or defer for follow-up.  CARB will participate in community meetings and TAC meetings unless mutually agree upon with CARB and the PI in cases where it could impact community engagement efforts negatively.

Task 7 Deliverables: The Technical Advisory Group will provide comments and input on the methodology and on the results of the study to inform the progress of the contract and to be included in the final report.

Task 8: Meeting, Reporting, preparation of draft final report

This will be a collaborative project where the investigators will work closely with CARB staff and building upon the methods used in previous and ongoing studies in developing the methods to be used for the exposure assessment including the details of the sampling campaign and the method used to develop the exposure. The methods should assure that the exposures can determine the levels of exposure to tire and brake wear in community air so that the health impacts of these exposures can be evaluated. The results of the study should help CARB to better understand the impacts of brake and tire wear particles in overburdened communities. In order to collaborate and maintain open communications meetings will be conducted with CARB staff and the investigators at least monthly.

Task 8 Deliverable: Monthly or more frequent meeting with CARB staff and submission of a monthly progress report. A draft final report will be due 6 months before the end of the project and will be reviewed and modified according to input by CARB staff. The final report will include a section on the limitations of the methods used in the study. A lay oriented kickoff meeting at the beginning and a lay oriented review of findings at the end will be conducted. A lay-oriented fact sheet about the project findings will also be prepared. Interim deliverables will be produced for each year of the project.

Deliverables

The project proposal must include but is not limited to the following deliverables:

At Pre-Proposal Stage

• Provide a cultural competency statement in the pre-proposal.
• Provide a community engagement plan in the pre-proposal.

At Beginning of Contract

• All researchers must undergo cultural competency training (examples include implicit bias training, racial equity training, etc.). Trainings should be completed or scheduled within 30 days of contract execution.
• A lay oriented kickoff meeting at the beginning and lay oriented review of findings at the end.

During Active Contract Period

• Quarterly Progress Reports and conference calls; The progress reports will include plain-language summaries that can be posted publicly. A progress report template will be provided.
• Consultation calls with CARB and key stakeholders. Suggested frequency is monthly, but could be more often if needed and could be as frequently as biweekly.
• A complete workplan for the study will be developed in consultation with CARB staff and with input from the Technical Advisory Group by the end of Quarter 2 to include the study design.
• Community engagement materials: flyers, presentation slides, prompts and speaking notes shall be co-created with CARB input.
• Submit deliverables at the end of each task to ensure that progress is being made.
• Interim-deliverables for each year of the project.

Prior to Contract Close

• All data, analyses and analytical tools generated through the course of this project
• Produce plain-language fact sheets about the project findings, including suggestions for preventative actions (if such information is available) and these will be translated into Spanish
• Draft final report
  • A copy-edited draft final report, reviewed and approved by the Principal Investigator
  • Include a plain language summary in draft final report
  • Include an equity implications section in draft final report
  • (If Applicable) Community peer review prior to finalizing draft final report
• Work with CARB to create plain-language outreach deliverables for public summarizing results and impact of project (available in multiple languages);
• Final Report (ADA-compliant) and virtual or in-person seminar
• Peer reviewed publications should be publicly available (please budget for this expense; submission-ready publications shall be reviewed by CARB staff).
• Additional deliverables to be determined in consultation with CARB staff.

Timeline

It is anticipated this project will be completed in 24 months from the start date. Cost shall not exceed $850,000.

Scoring Criteria

Responsiveness to the goals and objectives outlined in the proposal solicitation(15 points)

Proposers should demonstrate a clear understanding of the policy objectives and research needs that CARB seeks to address with this project and should convey their knowledge of the subject. The proposal should have a clear research question or testable hypothesis. The proposal should consider various aspects of the research need and identify or acknowledge biases. The proposal should spell out, in adequate detail, exactly what the Proposer proposes to do to satisfy the requirements of the Solicitation. The draft proposal must propose work that would satisfy the objective(s) stated in the Research Solicitation:

The objective of this study is to assess NEE exposure and health risks focused on a region with overburdened communities with high exposures to traffic pollution and NEE.

Policy relevance/benefits to the state(10 points)

Does the proposal describe how the project will provide data, information, and/or products to help CARB accomplish its mission?

Results will help CARB to understand the impacts of brake and tire wear emissions on health and particle toxicity. It will also help CARB understand exposure disparities for communities exposed to higher levels of NEE. The information provided by this study could inform policies and programs to reduce the impacts of NEE in vulnerable communities in California.

Previous work (15 points)

Do the researchers have relevant experience in this area? Is the team composed of a multidisciplinary team of experts? Do they discuss how they will build upon previous relevant work that was funded by CARB, other state agencies, and any other organizations you believe are appropriate (e.g. the U.S. EPA, U.S. Department of Energy)? If including community engagement, the relevant research partner should describe previous experience in community engagement and provide letters of support, references or a community impact statement, describing how previous work impacted communities. 5 points will be reserved for project teams that meet at least one of the following criteria:

1. The project team is multi-disciplinary
2. The project team members come from various universities or include non-academic institutions or community-based organizations
3. The project team includes one or more members, contributing significantly to the project (i.e. a principle investigator, co-principle investigator or co-investigator, contributing 25% or more of their time to the project) who have not worked with CARB in the past 5 years.

Technical merit (25 points)

Describe the submission's technical strengths and/or weaknesses. Proposers should demonstrate the logic and feasibility of the methodology and technical approach to the project, spell out the sequence and relationships of major tasks, and explain methods for performing the actual work. The proposal should provide an explanation of how the proposed methods are robust and how results will be validated. Please factor in how well the draft proposal describes these areas:

1. Is this the correct measurement approach, are these appropriate technologies being examined, will their proposed analysis produce the relevant results, etc.
2. Does the proposed work address all the deliverables required in section “Deliverables”? If not, the proposal should not be considered for funding.
3. The review team will be selecting only one draft proposal for development into a full proposal. If this draft proposal has potential, what areas or topics should be prioritized or better explained in the full proposal?

Level and quality of effort to be provided(15 points)

Does the proposal allocate time and resources in such a way that the objectives of the study will be met? Is supervision and oversight adequate for ensuring that the project will remain on schedule? Is the distribution of workload appropriate for activities such as research, evaluation and analysis, data reduction, computer simulation, report preparation, meetings, and travel?

Cost effectiveness (20 points)

Does the cost seem appropriate for the proposed work?  Does the proposed work seem feasible within the requested budget?  Projects that provide co-funding should be evaluated more favorably.

Scoring Criteria Scoring Guidance

91-100 points. Exceptionally strong. The submission is technically strong, meets stated research objectives, is cost-effective, and has a high potential to be successfully completed.

81-90 points. Strong. The submission is technically sound.

71-80 points. Mixed. The submission has either strong technical merit or strong policy significance, but not both.

61-70 points. Weak. The submission is not sufficiently linked to needs of the Board and offers limited technical merit.

60 points or below. Unacceptable. The submission is not linked to interests or needs of the Board and lacks technical merit.

[1]Brake & Tire Wear Emissions | California Air Resources Board

[2]https://ww2.arb.ca.gov/effects-brake-and-tire-wear-particulate-matter-composition-reactive-oxygen-species-placental

[3]Aerosol oxidative potential in the Greater Los Angeles area: source apportionment and associations with socioeconomic position. Shen, Jiaqi, Sina Taghvaee, Chris La, Farzan Oroumiyeh, Jonathan Liu, Michael Jerrett, Scott Weichenthal et al. "Aerosol oxidative potential in the Greater Los Angeles area: source apportionment and associations with socioeconomic position." Environmental Science & Technology 56, no. 24 (2022): 17795-17804.

[4]Aerosol oxidative potential in the Greater Los Angeles area: source apportionment and associations with socioeconomic position Shen, Jiaqi, Sina Taghvaee, Chris La, Farzan Oroumiyeh, Jonathan Liu, Michael Jerrett, Scott Weichenthal et al. "Aerosol oxidative potential in the Greater Los Angeles area: source apportionment and associations with socioeconomic position." Environmental Science & Technology 56, no. 24 (2022): 17795-17804.

[5]https://ww2.arb.ca.gov/effects-brake-and-tire-wear-particulate-matter-composition-reactive-oxygen-species-placental

[6]Lee, S.J., Demokritou, P., Koutrakis, P., Delgado-Saborit, J.M., 2006. Development and evaluation of personal respirable particulate sampler (PRPS). Atmos. Environ. 40, 212–224. https://doi.org/10.1016/j.atmosenv.2005.08.041.

[7]Dillner, A.M., Shafer, M.M., Schauer, J.J., 2007. A novel method using Polyurethane foam (PUF) substrates to determine trace element concentrations in size-segregated atmospheric particulate matter on short time scales. Aerosol Sci. Technol. 41, 75–85. https://doi.org/10.1080/02786820601113282.

[8]Pakbin, P., Ning, Z., Shafer, M.M., Schauer, J.J., Sioutas, C., 2011. Seasonal and spatial coarse particle elemental concentrations in the Los Angeles area.  Aerosol Sci.Technol. 45, 949–963. https://doi.org/10.1080/02786826.2011.571309

[9]Aerosol oxidative potential in the Greater Los Angeles area: source apportionment and associations with socioeconomic positionShen, Jiaqi, Sina Taghvaee, Chris La, Farzan Oroumiyeh, Jonathan Liu, Michael Jerrett, Scott Weichenthal et al. "Aerosol oxidative potential in the Greater Los Angeles area: source apportionment and associations with socioeconomic position." Environmental Science & Technology 56, no. 24 (2022): 17795-17804.