Thread by @vera_tenacious

🧵Do-it-yourself (DIY) air cleaners: Evidence on effectiveness and considerations for safe operation

Angela Eykelbosh, Environmental Health and Knowledge Translation Scientist, @ncceh National Collaborating Centre for Environmental Health
Jan 18/23

LINK: ncceh.ca/documents/evid…

Do-it-yourself (DIY) air cleaners: Evidence on effectiveness and considerations for safe operation

Angela Eykelbosh, Environmental Health and Knowledge Translation Scientist, @ncceh National Collaborating Centre for Environmental Health
Jan 18/23

PDF: ncceh.ca/sites/default/…

#COVID19 #SARSCoV2 #Wildfire #WildfireSmoke #COVIDisAirborne #Radon #IndoorAir #IAQ #CleanTheAir #Engineering #corsirosenthalbox #pollution #fineparticulates #aerosols #airborne #disease #publichealth #healthcare #cleanair #environment #publicsafety #fireseason #cdnpoli

"Portable air cleaners are filtration-based devices that remove particulate matter (PM) from indoor air. Due to the COVID-19 pandemic & the increasing impacts of wildfire smoke, portable air cleaners have become an important tool for public health protection."
-@ncceh, Jan 18/23

"Portable air cleaners can be used to reduce PM exposure in several different contexts, such as..."

- to reduce the presence of respiratory pathogens
- to remove smoke that gets indoors
- to reduce exposure to pollen indoors
- to reduce exposure to pollutants and allergens

This document reviews evidence on DIY air cleaner effectiveness, cost effectiveness, energy efficiency and noise compared with commercial units & is intended to assist with decision-making regarding potential use of DIY air cleaners in both residential & nonresidential settings.

A) 1 filter and 1 fan (1×1 design); B) 2 filters and 1 fan (2×1 or “wedge” design); C) 3 filters and 2 fans (3×2 design); D) 4 filters and 1 fan (4×1 or Corsi-Rosenthal box); E) 5 filters and 1 fan (5×1 design) with supports to elevate the device; F) Bottom view of 5×1 design

"Although differences in the methods and materials make it difficult to compare CADR across studies, within-study comparisons showed that DIY [air cleaner/#corsirosenthalbox] designs consistently performed comparably with commercial [HEPA air cleaner] units."
-@ncceh, Jan 18/23

"Furthermore, the relatively high CADR values combined with the low cost of construction meant that DIY [air cleaner/#corsirosenthalbox] designs had a much lower cost per CADR values ($0.06-0.83) than commercial [HEPA air cleaner] units ($0.64-6.80)."

"DIY [air cleaner/#corsirosenthalbox] designs also met or exceeded the @ENERGYSTAR threshold of 2 cfm/W in all but 2 studies that reported on energy efficiency, making them comparable w/ commercial units. Overall, DIY air cleaners were marginally noisier than commercial units..."

Overall, field experiments showed DIY air cleaning units were effective for increasing ACH & reducing PM exposure... Previous work examining use of C02 sensing in schools suggests user engagement & training are critical to success when attempting to manage #IAQ at the room level.

The best design for a given space will depend on multiple factors, including:

- size of the space
- cost of materials
- materials available

In general, CADR values from reported studies increased with more filters, thicker filters & filters with higher ratings #IAQ #filtration

Other important design considerations include the following:

- sealing the gaps
- using a fan "shroud"
- using a newer fan to minimize risk of burns and fire

Proposing a quality control strategy for DIY air cleaners is challenging because methods used to evaluate #CADR in commercial air cleaners require expert knowledge & costly equipment... the simplest & most user-friendly approach may be to monitor PM with mobile, low-cost sensors.

US Environmental Protection Agency (@EPA) has recently released the Enhanced Air Sensor Guidebook, a comprehensive resource on the use of low-cost air quality sensors, including PM (particulate matter) sensors. epa.gov/air-sensor-too…

The @EPA Enhanced Air Sensor Guidebook is part of their Air Sensor Toolbox, a collection of resources for understanding low-cost air sensors and how they can be used to understand indoor and outdoor air quality through community science. epa.gov/air-sensor-too…

Recommendations for operating DIY air cleaners safely?

- know the hazard you are addressing
- do not leave unit unattended; keep it clear of walls, furniture and curtains
- mixing is good; drafts and noise are bad
- change filters as needed
- know when to buy a commercial unit

Portable [HEPA/DIY #corsirosenthalbox] air cleaners are effective in removing particulate matter [and aerosols] from room air but not other problematic indoor air pollutants, such as:

- radon
- volatile organic compounds
- carbon monoxide (CO)
- carbon dioxide (CO2)

#IAQ

DIY air cleaners do not replace the need for adequate ventilation & are not a long-term solution for spaces w/ poor #IAQ. Rather, they should be considered a useful supplementary measure to improve #IAQ in combination w/ existing ventilation or to address imminent health hazards.

"With respect to the #COVID19 pandemic, portable air cleaners can be used to reduce the amount of virus in the air and on surfaces.... they remain a complement to other critical health protective measures such as vaccination, staying home when sick, masking, ventilation..."

"DIY air cleaners are a safe and effective alternative to more expensive commercial portable air cleaners, providing comparable CADR for lower material costs and without excessive energy usage or large differences in noise generation."
-@ncceh, Jan 18/23

#cdnpoli #IAQ #cleanair

- choose a #corsirosenthalbox design appropriate for the space, its occupants, their activities, and follow best practices
- consider how or whether air cleaner effectiveness can be verified in situ using low-cost PM sensors
- engage with building occupants to ensure success

"DIY air cleaners appear to be a valuable, low-cost tool to reduce hazardous [particulate matter and aerosol] exposures."
- National Collaborating Centre for Environmental Health @ncceh, January 18, 2023

Web Link: ncceh.ca/documents/evid…
PDF Link: ncceh.ca/sites/default/…

https://twitter.com/ncceh/status/1616128697869778990