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Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog.

ABSTRACT: SARS-CoV-2 has severely affected capacity in the National Health Service (NHS), and waiting lists are markedly increasing due to downtime of up to 50 min between patient consultations/procedures, to reduce the risk of infection. Ventilation accelerates this air cleaning, but retroactively installing built-in mechanical ventilation is often cost-prohibitive. We investigated the effect of using portable air cleaners (PAC), a low-energy and low-cost alternative, to reduce the concentration of aerosols in typical patient consultation/procedure environments. The experimental setup consisted of an aerosol generator, which mimicked the subject affected by SARS-CoV-19, and an aerosol detector, representing a subject who could potentially contract SARS-CoV-19. Experiments of aerosol dispersion and clearing were undertaken in situ in a variety of rooms with two different types of PAC in various combinations and positions. Correct use of PAC can reduce the clearance half-life of aerosols by 82% compared to the same indoor-environment without any ventilation, and at a broadly equivalent rate to built-in mechanical ventilation. In addition, the highest level of aerosol concentration measured when using PAC remains at least 46% lower than that when no mitigation is used, even if the PAC's operation is impeded due to placement under a table. The use of PAC leads to significant reductions in the level of aerosol concentration, associated with transmission of droplet-based airborne diseases. This could enable NHS departments to reduce the downtime between consultations/procedures.

SUBMITTER: Salmonsmith J

PROVIDER: S-EPMC9990385 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature

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Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog.

Salmonsmith Jacob J Ducci Andrea A Balachandran Ramanarayanan R Guo Liwei L Torii Ryo R Houlihan Catherine C Epstein Ruth R Rubin John J Tiwari Manish K MK Lovat Laurence B LB

Epidemiology and infection 20230118

SARS-CoV-2 has severely affected capacity in the National Health Service (NHS), and waiting lists are markedly increasing due to downtime of up to 50 min between patient consultations/procedures, to reduce the risk of infection. Ventilation accelerates this air cleaning, but retroactively installing built-in mechanical ventilation is often cost-prohibitive. We investigated the effect of using portable air cleaners (PAC), a low-energy and low-cost alternative, to reduce the concentration of aeros ...[more]

PMID: 36650731

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Project description:IntroductionMany school buildings have inadequate ventilation, rudimentary if any air filtration, and aging and poorly maintained mechanical systems, all of which can lead to poor indoor air quality (IAQ). These issues are especially acute in environmental justice (EJ) communities where schools are located in polluted areas. This community-based participatory research examines how IAQ in naturally ventilated school buildings is affected by the use of air purifiers, air change rates, outdoor pollution levels, and teacher and staff behavior.MethodsIAQ assessments were performed at two schools in Detroit, Michigan, which included building walk-through inspections and continuous indoor and outdoor measurements of black carbon (BC), particulate matter (PM10 and PM2.5), carbon dioxide (CO2), air change rates (ACRs), temperature, humidity, and sound pressure levels. Air purifiers with usage monitors were then installed, and the IAQ assessments were repeated. Teachers were surveyed before and after purifier deployment.ResultsAt baseline, classrooms had low ACRs (0.58-1.38 h-1), moderate PM2.5 levels (2.8-8.9 μg/m3), highly variable PM10 concentrations (4.7-37.5 μg/m3), and elevated BC levels (0.3-0.7 μg/m3), reflecting emissions from local traffic, industry and other sources. The installation and use of purifiers reduced pollutant levels and the overall performance matched the predictions of a single compartment model. However, daily reductions varied widely among classrooms, reflecting differences in teacher behavior regarding the frequency of opening windows and the operation of purifiers, including differences in purifier fan speed settings and whether purifiers were used at night. Survey responses indicated that many teachers were aware of IAQ problems. The higher rates reported for health symptoms and dissatisfaction at one school may have lowered the teachers' tolerance to noise and reduced purifier use.DiscussionThe study helps explain the variation reported in prior studies using purifiers, and it reinforces the need to monitor IAQ and purifier use, use enhanced filtration and increase ventilation, and engage with teachers and school staff to support and maintain IAQ programs in schools.

Project description:BackgroundThe role of portable high-efficiency particulate air (HEPA) filters for supplemental aerosol mitigation during exercise testing is unknown and might be relevant during COVID-19 pandemic.Research questionWhat is the effect of portable HEPA filtering on aerosol concentration during exercise testing and its efficiency in reducing room clearance time in a clinical exercise testing laboratory?Study design and methodsSubjects were six healthy volunteers aged 20 to 56 years. In the first experiment, exercise was performed in a small tent with controlled airflow with the use of a stationary cycle, portable HEPA filter with fume hood, and particle counter to document aerosol concentration. Subjects performed a four-stage maximal exercise test that lasted 12 min plus 5 min of pretest quiet breathing and 3 min of active recovery. First, they exercised without mitigation then with portable HEPA filter running. In a separate experiment, room aerosol clearance time was measured in a clinical exercise testing laboratory by filling it with artificially generated aerosols and measuring time to 99.9% aerosol clearance with heating, ventilation, and air conditioning (HVAC) only or HVAC plus portable HEPA filter running.ResultsIn the exercise experiment, particle concentrations reached 1,722 ± 1,484/L vs 96 ± 124/L (P < .04) for all particles (>0.3 μm), 1,339 ± 1,281/L vs 76 ± 104/L (P < .05) for smaller particles (0.3 to 1.0 μm), and 333 ± 209/L vs 17 ± 19/L (P < .01) for larger particles (1.0 to 5.0 μm) at the end of the protocol in a comparison of mitigation vs portable HEPA filter. Use of a portable HEPA filter in a clinical exercise laboratory clearance experiment reduced aerosol clearance time 47% vs HVAC alone.InterpretationThe portable HEPA filter reduced the concentration of aerosols generated during exercise testing by 96% ± 2% for all particle sizes and reduced aerosol room clearance time in clinical exercise testing laboratories. Portable HEPA filters therefore might be useful in clinical exercise testing laboratories to reduce the risk of COVID-19 transmission.

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Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog.

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Use of portable air purifiers to reduce aerosols in hospital settings and cut down the clinical backlog.

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