California Air Resources Board

Pre-proposal Solicitation Scope of Work for:

Characterization of Air Pollutant Emissions and Possible Health Effects Associated with Air Cleaning Devices Using Electronic Air Cleaning Technologies (White Paper)

1. Objectives of White Paper

CARB is soliciting a proposal for a White Paper that will identify and describe current and emerging electronic air cleaning technologies, including how these technologies are employed, any non-ozone emissions from their use, and potential health effects associated with exposure to emissions from these devices.  The white paper will also identify gaps in knowledge and pertinent regulatory efforts in other jurisdictions.  This information may be used by CARB to better understand possible health effects, design future research studies to address gaps in knowledge, and to provide relevant information to state and local agencies and the public about indoor air cleaning devices. 

2. Background to Air Cleaner Regulation

In 2006, Assembly Bill (AB) 2276 (Pavley, Stats. 2006, ch. 770) directed CARB to adopt regulations to protect public health from ozone emitted by indoor air cleaning devices. The air cleaner regulation requires that most indoor air cleaners sold to people or businesses in California be certified by CARB as not exceeding the ozone emission limit of 50 ppb (0.050 ppm).  Extensive scientific research shows that exposure to ozone causes respiratory symptoms, reduced lung function, increased airway hyperreactivity, and increased airway inflammation.  Additionally, exposure to ozone has been associated with asthma onset and exacerbation, increased school absences, hospitalizations due to respiratory diseases, and premature death.  The regulation has successfully reduced the potential for Californians to be exposed to ozone from portable indoor air cleaning devices.  To date, CARB has certified more than 4,500 air cleaning devices manufactured by over 700 companies.  In 2020, amendments to the regulation were adopted that require electronic in-duct air cleaning devices to be CARB certified before October 1, 2022. 

Over the last decade, the air cleaner market has diversified, with new electronic air cleaning technologies being employed in an expanding array of devices.  In recent years, the California market has also dramatically increased due to public concern about exposure to wildfire smoke and the coronavirus pandemic. Previous market research projected a nearly 5% annual increase in sales of air purifiers to consumers, which has likely expanded as businesses respond to consumer concerns by installing air purification devices in public spaces, including schools, childcare settings, nursing homes and restaurants.

Air Cleaning Technologies, Emissions, and Health Impacts

Physical removal of pollutants by air cleaning devices can be affected by using mechanical filtration, such as HEPA filters, or with sorbent materials, which do not result in emissions from the device.  Other types of electronic air cleaning technologies, such as UV lamps, ionization, and photocatalytic oxidation, may result in emissions that can react with gaseous chemicals, particulates, and biological components in indoor air, potentially resulting in the formation of secondary byproducts.  For example, prior research shows that highly reactive ions emitted from air cleaners utilizing bipolar ionization or hydroxyl radical generation can interact with pollutants in indoor air to form increased concentrations of particulate matter, including ultrafine particles, as well as other reactive chemicals (Collins and Farmer, 2021).  

The rapid expansion in the use of portable and in-duct air cleaning devices by homeowners, and in commercial properties and public spaces, has led to concerns about potential health impacts from exposure to harmful emissions, such as chemical by-products and ultrafine particles. Epidemiological studies on health effects from the short-term use of mechanical air purifiers using HEPA filtration alone found improvement in respiratory and cardiac function (Chen et. al. 2015; Park et. al. 2016).  In contrast, studies evaluating the formation of chemical by-products, including formaldehyde, and the release of charged nanoparticles from the use of photocatalytic oxidation air purifiers raise questions about potential health effects from inhalation of these pollutants (Destaillats et. al. 2012; Costarramone et. al. 2015).  Recent research on health effects from exposure to negative ions emitted from air purifiers found evidence of cardiac effects in both middle school students (Liu et. al. 2020a) and college students (Liu et. al. 2020b).  

Therefore, the primary goal of this white paper is to document and analyze available research on electronic air cleaning technologies, including the emission/creation of harmful air pollutants from the use of air cleaners with electronic air cleaning components and potential health effects related to exposure to these emissions/pollutants. Identification of population sub-groups who may be especially vulnerable to health effects from exposure to emissions from or pollutants formed by electronic air cleaning devices is also an important component of this evaluation.

3. Scope of Work

   1. Conduct a literature review of research studies and review of commercial marketing materials on existing and emerging electronic air cleaning technologies, including non-ozone emissions, pollutant formation, and chemical degradation by-products of potential concern.
   2. Conduct a literature review of toxicological and epidemiological studies on exposure to emissions of non-ozone chemical by-products from the use of electronic air cleaning devices.
   3. Identify U.S. and international regulations of air cleaning technologies.
   4. Identify data gaps in existing research.
   5. Summarize findings in White Paper, including recommendations for future research and identification of any population subgroups who may be vulnerable to health effects associated with exposure to non-ozone emissions from electronic air cleaners.

4. Deliverables

During Active Contract Period

• Work with CARB staff at the beginning of the project to create a half-page plain-language outreach deliverable for the public describing the project’s goals, process, and planned deliverables (available in multiple languages, template will be provided).
• 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

Prior to Contract Close

• Final data products created under this contract include all data, analyses and analytical tools generated through the course of this project
• Draft final report
  • Include a plain language summary in draft final report
  • Include an equity implications section in draft final report, specifically the identification of vulnerable population subgroups
• Work with CARB to create plain-language outreach deliverables for public (available in multiple languages)
• Final report and virtual or in-person seminar

Additional deliverables to be determined in consultation with CARB staff.

5. Timeline

The timeline to completion is 12 months from the start of the contract. Cost shall not exceed $25,000.

Scoring Criteria

1. Responsiveness to the Goals and Objectives Outlined in the Proposal Solicitation(30 points) The proposal should spell out, in adequate detail, exactly what the Proposer intends to do to satisfy the requirements of the Solicitation, which include : documenting and analyzing available research on electronic air cleaning technologies, including the emission/creation of harmful air pollutants from the use of air cleaners with electronic air cleaning components; identify potential health effects related to exposure to these emissions/pollutants; provide recommendations for future research that supports CARB air cleaner certification program.
    
2. PREVIOUS WORK (20 points) – Do the researchers have relevant experience in the areas of assessing environmental or public health impacts from air cleaning technologies, or related work
    
3. TECHNICAL MERIT (30 points) - Is the proposal sufficiently detailed and indicate a methodical approach to analyzing available research studies, technical documents, and data to formulate sound conclusions in support of the goals of the project, including identifying any population subgroups vulnerable to exposures to non-ozone emissions associated with the use of electronic air cleaning technologies?
    
4. 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?