California Air Resources Board

Scope of Work

Background

Residential fossil fuel appliances emit a wide range of air pollutants, either through fuel leakage or as combustion byproducts. These air pollutants include criteria air pollutants (e.g. NO₂, CO, particulate matter, and sulfur oxide), GHGs (e.g. methane, carbon dioxide), and toxic air contaminants (TACs, e.g., formaldehyde, hydrogen cyanide, and benzene). Some of the emissions occur indoors and thus deteriorate indoor air quality. In addition, all emissions are eventually released to the ambient air and increase ambient air pollutant levels. These air pollutants have been linked to various acute and chronic health effects, including respiratory illness, cardiovascular disease, and premature death. Lower-income households may be at even higher risk of illness from exposure to these air pollutants. This is due to their smaller residential unit size, higher occupant density, insufficient ventilation, and use of gas ranges as heating sources; in addition, these households are often subjected to increased exposure from outdoor pollution sources such as traffic and industry.

This contract is focused on investigating TACs from indoor appliances. While studies measuring TACs from appliances are limited, initial studies have found significant levels of TACs and potential health effects. Girman et al. (1989) tested one gas stove and 10 gas space heaters and found the emission rates of formaldehyde from gas combustion ranged from 0.43 to 20.3 µg/kJ. Singer et al. (2009) tested 13 cooktop sets, 12 ovens, five broiler burners, five storage water heaters, four forced air furnaces, one wall furnace, and six tankless water heaters. This study found the emission rates of formaldehyde from gas combustion ranging from 0.09 to 5.5 µg/kJ. A recent California study (Kashtan et al., 2023) quantified the emissions of benzene from gas combustion by stoves. The study found mean benzene emissions from gas and propane burners on high and ovens set to 350°F ranged from 2.8 to 6.5 μg min^–1, and led to raised kitchen benzene concentrations that were above the upper range of indoor benzene concentrations attributable to secondhand tobacco smoke. Benzene from gas stoves also migrated throughout homes, in some cases elevating bedroom benzene concentrations above the California Office of Environmental Health Hazard Assessment (OEHHA) chronic Reference Exposure Level (REL) for hours after the stove was turned off. Another California study (Lebel et al., 2022) found that TACs could continuously leak into indoor environments, even when gas ranges were not in use. This study detected 12 chemicals of concern, such as benzene, toluene, ethylbenzene, and xylene in unburned natural gas (NG) samples collected from residential NG stoves. Modeling simulation indicated leakage from gas stoves could result in indoor benzene concentrations higher than the OEHHA 8-hour REL in a small fraction of homes with an elevated leakage rate of benzene and a low ventilation rate.

While these studies shed light on TAC emissions from residential heating and cooking appliances, a comprehensive investigation is needed to systematically characterize the profile of TACs from these appliances. Additionally in alignment with the 2022 Scoping Plan for Achieving Carbon Neutrality, CARB is in the process of developing and proposing zero-emission GHG standards for new space and water heaters sold in California. These standards would also result in important reductions of other air pollutants from these appliances, including TACs, and support California’s attainment efforts for State and federal air quality standards as well as achieving public health benefits. The results from this research provide better understanding of the impacts of TAC emissions from heating and cooking appliances used in California homes, facilitate the assessment of the co-benefits of zero-emission appliance standards to be developed, and inform possible future regulatory actions that limit TAC emissions from these appliances and protect public health.

Objective

The objectives of this research are to:

1. Test a representative sample of residential fossil fuel combustion space and water heating and cooking appliances, and determine the potential composition, concentration, and emission rates of TACs in fuel leakage and combustion exhaust sampling;
2. Assess the contributions of their TAC emissions on indoor and to outdoor air quality, separately and combined;
3. Estimate the health impacts of indoor and outdoor exposures to TACs attributable to these appliances; and,
4. Evaluate the exposure and health impact disparity among communities associated with TAC emissions from these appliances.

The results will enable us to understand exposures to TACs attributable to residential heating and cooking appliances and the associated health risks, which will assist policymakers in assessment of the benefits of related policies that reduce TAC emissions from these appliances.

Task 1: Literature Review

The researchers should conduct a comprehensive review of existing information related to TAC emissions from residential space and water heating and cooking appliances, the associated impacts on air quality and public health, and exposure and health impact disparity attributable to these appliances. Information related to air quality and health impacts, such as building characteristics, operation activities of appliances, and health assessment tools for TACs, should also be collected. The review could include but is not limited to peer-reviewed articles, research reports by research institutes and government agencies, consumer product reports, product marketing materials, relevant databases, and case studies.

Task 2: Technical Advisory Group and Community Partners

The researchers should assemble a Technical Advisory Group (TAG) to guide the study design and execution, and to review interim deliverables as well as the final report. The TAG could consist of representatives who have extensive knowledge related to emissions, technology, market, and/or policies of residential appliances, such as state and local agencies, industry groups, academia, and community representatives. The researchers should also recruit three to five community partners across the state as subcontractors, and a budget should be allocated to pay their work. The community partners’ roles in this study include 1). reviewing the study design, 2). guiding the selection and testing of appliances that reflect the mix of appliances in disadvantaged communities as designated by CalEPA for SB 535, and 3). assisting the analysis of exposure and health impact disparity. The researchers should submit a draft list of TAG members and community partners to CARB staff for approval.

Task 3: Study Design

The researchers should submit a written study plan to CARB staff that includes but is not limited to the following components:

1. A clearly defined research question focused on researching TACs from indoor appliances along with a breakdown of objectives that are feasible to achieve, a list of toxic emissions to be investigated, and a list of expected results that will meet CARB’s needs.
2. A detailed method regarding: 1) how to determine and obtain representative samples of appliances for testing including sampling within and among the disadvantaged communities selected for this study, 2) how to collect air samples in fuel leakage and combustion exhaust, 3) how to profile the compositions of TACs in the air samples, and measure their emission rates and concentrations, 4) how to quantify the contributions to indoor and outdoor air quality, 5) how to use the results from this study to estimate impacts on air quality to public health, and 6) how to analyze the exposure and health disparity attributable to these appliances.
3. A detailed quality assurance and quality control plan.
4. A detailed description of existing facilities or equipment to be used in this study, or a plan to obtain the facilities or equipment needed for this study.
5. A description of research experience and established collaboration with relevant stakeholders that will be leveraged for this study.
6. A description of anticipated obstacles and potential solutions or backup plans.

Task 4: Characterization of Representative Appliances for Testing

The researchers should utilize information about the California residential appliances stock provided by CARB to assist in characterizing the current appliance mix and future projections if possible. The characterization of these appliances should include but is not limited to any parameters that might impact air pollutant emissions such as energy sources, models, NOx control levels and technologies, sizes, ages, fuel consumptions, operation activities, housing types (e.g., single-family homes, multi-family homes, and manufactured homes), homeownership, geographical locations or climate zones, and other information related to installation, operation, and ventilation.

Based on the characterization and in consultation with CARB staff, the researchers should decide on a combination of appliances for testing so that they represent the residential heating and cooking appliance mix in California for different housing types and different climate zones. The number of appliances to be tested should be sufficient to provide statistically meaningful results. More weight should be given to disadvantaged communities to assist in the analysis of potential exposure and health impact disparities in these communities. The researchers should work with community partners to obtain samples that reflect the appliance mix in these communities. The researchers should submit a list of appliances to be tested to CARB staff for approval.

Task 5: Compositions and Emission Rates

The researchers should collect air samples, both at the points of fuel leakage and combustion exhaust, for each appliance, analyze TAC compositions, and determine their emission rates and concentrations. Desired TACs include but are not limited to formaldehyde, hydrogen cyanide, benzene, toluene, ethyl-benzene, xylene, and hexane. In consultation with CARB staff and the TAG, the researchers should determine a set of key TACs for further analysis. The selection could be based on metrics such as the prevalence, concentrations, and health effects. Then the researchers should quantify the emission rates and concentrations of these key chemicals for leakage and combustion, respectively. The researchers should submit a summary report about the emission rate and concentration results to CARB staff.

Task 6: Air Quality and Health Impact Assessment

The researchers should determine the changes in TAC concentrations indoors and outdoors due to the emissions from these appliances, and then estimate the overall contributions to indoor and outdoor air quality statewide. Furthermore, the researchers should assess the health impacts associated with such air quality impacts. Comparisons between disadvantaged communities and the general population should be made to assess the exposure and health impact disparity attributable to these appliances. The researchers should submit a summary report on the impact analysis to CARB staff, the TAG and community partners for review.

Task 7: Kick-off Meeting, Progress Update, Final Report and Presentation

At the beginning of the project, a kick-off meeting will be held with CARB staff to discuss the details and timeline of the project. Quarterly progress reports will be prepared and delivered to CARB with each invoice, containing brief narrative summaries of achievements, the state of progress relative to the plans, and any significant problems encountered along with a brief description of the solutions. Quarterly progress update meetings will be held with CARB staff to discuss the progress, problems, and potential solutions.

A copy-edited draft report will be submitted to CARB for review six months before the end date of the project. The revised ADA compliant final report that addresses all comments from the TAG, CARB staff, and the public will be prepared and submitted to CARB before the end date of the project. A seminar in plain language will be presented by the principal investigator to the CARB staff and the public. An electronic copy of all data generated by this study also will be provided to CARB.

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.

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.

During Active Contract Period

• Quarterly Progress Reports and Progress Update Meetings. The progress reports will include plain-language summaries that can be posted publicly. A progress report template will be provided. The progress update meetings will be held virtually to present the project progress to CARB staff and the public each quarter.   
• Consultation calls with CARB and key stakeholders. Suggested frequency is monthly.
• Interim reports, including: 1) a written study plan, 2) a draft list of technical advisory group members, 3) a draft list of appliances that will be tested, 4) a summary of emission rate and concentration results, 5) a summary of air quality and health impact results

Prior to Contract Close

• All data, analyses and analytical tools generated through the course of this project will be submitted to CARB.
• Produce plain-language fact sheets, including suggestions for preventative actions (if such information is available,) and these will be translated into Spanish.
• Draft final report
  • 6 months prior to contract close, provide a 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.
  • Must be copy-edited.
• Work with CARB to create plain-language outreach deliverables for public summarizing results and impact of project (available in multiple languages).
• Final Report and virtual or in-person lay-friendly 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 36 months from the start date. Cost shall not exceed $900,000.

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: to systematically characterize the profile of TAC emissions from residential space and water heating and cooking appliances, and assess the impacts of such emissions on indoor and outdoor air quality and public health.

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? The 2022 Scoping Plan for Achieving Carbon Neutrality outlined the path to achieve carbon neutrality in 2045, and building electrification is an important measure for California to achieve this goal. CARB is in the process of developing and proposing zero-emission GHG standards for new space and water heaters sold in California. These standards would also result in important reductions of air pollutants, including TACs, from these appliances and assist California with meeting State and federal air quality standards as well as achieving public health benefits. The results from this research will help CARB assess the impacts of TAC emissions from heating and cooking appliances used in California homes.  This will facilitate the assessment of the co-benefits of zero GHG emission space and water heater standards to be developed, as well as the potential for regulation of TACs from these appliances.

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. Specifics of what the reviewer team should consider:
   1. Does the proposed method cover all the important TACs mentioned in task 4 of the SOW, including formaldehyde, hydrogen cyanide, and benzene?
   2.  Does the proposed method include all the key components: emission rate, concentration, and health assessment?
   3. Are the measurement and/or modeling approaches appropriate to provide scientific sound results?
   4. Does the research team have relevant experience in laboratory and field measurement, air quality modeling, and health analysis?
   5. Does the proposed work prioritize the measurement and analysis in priority communities and include analysis of exposure and health impact disparity?
   6. Will the results of the proposed work be useful for assessing the statewide benefits of reducing air toxic emissions from zero-emission appliance standards?
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.