ArticleThe Science of the total environment2022
Can 10× cheaper, lower-efficiency particulate air filters and box fans complement High-Efficiency Particulate Air (HEPA) purifiers to help control the COVID-19 pandemic?
Article in The Science of the total environment, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05944770 (ASPIRE), which is not on this map. Cited by 8 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
ASPIRE (Advancing Science Partnerships for Indoor Reductions of Smoke Exposures)-Health Tulare County
Who cites it
8 citing papers in PubMed, 1 synthesis or guideline pooled it.
- Managing infectious aerosols to counter engineered pandemics: Current recommendations and future research.Risk analysis : an official publication of the Society for Risk Analysis · 2025Guideline
- A two-year indoor-outdoor monitoring study of household clean air interventions during ambient and wildfire smoke periods in King County, Washington.Environmental research communications · 2026Article
- Quantification of Byproduct Formation from Portable Air Cleaners Using a Proposed Standard Test Method.Environmental science & technology · 2024Article
- Self-reported health impacts of do-it-yourself air cleaner use in a smoke-impacted community.Heliyon · 2024Article
- Cultivating community-based participatory research (CBPR) to respond to the COVID-19 pandemic: an illustrative example of partnership and topic prioritization in the food services industry.BMC public health · 2023Article
- Efficacy of Do-It-Yourself air filtration units in reducing exposure to simulated respiratory aerosols.Building and environment · 2023Article
- Control technologies to prevent aerosol-based disease transmission in animal agriculture production settings: a review of established and emerging approaches.Frontiers in veterinary science · 2023Review
- Impact of do-it-yourself air cleaner design on the reduction of simulated wildfire smoke in a controlled chamber environment.Indoor air · 2022Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
1 author.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Public health departments such as CDC and California Department of Public Health (CA-DPH) advise HEPA-purifiers to limit transmission of SARS-CoV-2 indoor spaces. CA-DPH recommends air exchanges per hour (ACH) of 4-6 air for rooms with marginal ventilation and 6-12 in classrooms often necessitating multiple HEPA-purifiers per room, unaffordable in under-resourced community settings. Pressure to seek cheap, rapid air filtration resulted in proliferation of lower-cost, Do-It-Yourself (DIY) air purifiers whose performance is not well characterized compared to HEPA-purifiers. Primary metrics are clean air delivery rate (CADR), noise generated (dBA), and affordability ($$). CADR measurement often requires hard-to-replicate laboratory experiments with generated aerosols. We use simplified, low-cost measurement tools of ambient aerosols enabling scalable evaluation of aerosol filtration efficiencies (0.3 to 10 μm), estimated CADR, and noise generation to compare 3 HEPA-purifiers and 9 DIY purifier designs. DIY purifiers consist of one or two box fans coupled to single MERV 13-16 filters (1″-5″ thick) or quad filters in a cube. Accounting for reduced filtration efficiency of MERV 13-16 filters (versus HEPA) at the most penetrating particle size of 0.3 μm, estimated CADR of DIY purifiers using 2″ (67%), 4″ (66%), and 5″ (85%) filters at lowest fan speed was 293 cfm ($35), 322 cfm ($58), and 405 cfm ($120) comparable to best-in-class, low-noise generating HEPA-purifier running at maximum speed with at 282 cfm ($549). Quad filter designs, popularly known Corsi-Rosenthal boxes, achieved gains in estimated CADR below 80% over single filter designs, less than the 100% gain by adding a second DIY purifier. Replacing one of the four filters with a second fan resulted in gains of 125%-150% in estimated CADR. Tested DIY alternatives using lower-efficiency, single filters compare favorably to tested HEPA-purifiers in estimated CADR, noise generated at five to ten times lower cost, enabling cheap, rapid aerosol removal indoors.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.