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COVID-19 Outbreak and Hospital Air Quality: A Systematic Review of Evidence on Air Filtration and Recirculation
COVID-19 Outbreak and Hospital Air Quality: A Systematic Review of Evidence on Air Filtration and Recirculation
The outbreak of SARS-CoV-2 has made us all think critically about hospital indoor air quality and the approaches to remove, dilute, and disinfect pathogenic organisms from the hospital environment. While specific aspects of the coronavirus infectivity, spread, and routes of transmission are still under rigorous investigation, it seems that a recollection of knowledge from the literature can provide useful lessons to cope with this new situation. As a result, a systematic literature review was conducted on the safety of air filtration and air recirculation in healthcare premises. This review targeted a wide range of evidence from codes and regulations, to peer-reviewed publications, and best practice standards. The literature search resulted in 394 publications, of which 109 documents were included in the final review. Overall, even though solid evidence to support current practice is very scarce, proper filtration remains one important approach to maintain the cleanliness of indoor air in hospitals. Given the rather large physical footprint of the filtration system, a range of short-term and long-term solutions from the literature are collected. Nonetheless, there is a need for a rigorous and feasible line of research in the area of air filtration and recirculation in healthcare facilities. Such efforts can enhance the performance of healthcare facilities under normal conditions or during a pandemic. Past innovations can be adopted for the new outbreak at low-to-minimal cost.
·pubs.acs.org·
COVID-19 Outbreak and Hospital Air Quality: A Systematic Review of Evidence on Air Filtration and Recirculation
Mechanisms by Which Ambient Humidity May Affect Viruses in Aerosols
Mechanisms by Which Ambient Humidity May Affect Viruses in Aerosols
"With prehumidification, recovery rates (± standard deviations) were much higher for nonenveloped viruses (T7 coliphage, 28% ± 19% with prehumidification versus 0.02% ± 0.01% without prehumidification; poliovirus, 29% ± 5% versus 3.2% ± 1.8%) but were unchanged for enveloped viruses (Semliki Forest virus [SFV], 32% ± 7% versus 42% ± 8%; Langat virus, 42% ± 10% versus 51% ± 12%) Benbough attributed the inactivation of nonenveloped viruses to structural rearrangement during abrupt rehydration in the impinger collection medium and suggested that slower rehydration rates, such as those experienced during the prehumidification process, were more favorable for polioviruses and coliphages" "Viruses that partition on the surface of aerosols may be subject to damage due to surface tension, shear stress, and conformational rearrangement driven by hydrophobicity." "Results showed that enveloped viruses lost infectivity dramatically (up to four orders of magnitude) due to aeration, while the nonenveloped ones did not." "Higher RH allows for larger final aerosol size and larger surface area due to less evaporation and, thus, greater potential for surface inactivation of hydrophobic lipid-containing viruses (i.e., enveloped viruses). Nonenveloped viruses are less likely to be affected." "While salts appear to be toxic to enveloped viruses, addition of salts to the medium has been shown to improve rather than reduce the viability of nonenveloped viruses... Benbough (1) suggested that salts can slow the rehydration process ... and thus reduce the chance of structural rearrangements that can be damaging in the capsid of nonenveloped viruses. Our interpretation of the enhanced viability is that salts can keep the aerosol and the virus in it from drying out completely at RHs above the ERH and thus reduce the chance of unwanted structural rearrangements during rehydration. This effect would benefit the nonenveloped viruses that need to retain their structural water; meanwhile, they are not susceptible to damage by salts, as are enveloped viruses."
·ncbi.nlm.nih.gov·
Mechanisms by Which Ambient Humidity May Affect Viruses in Aerosols
ASHRAE Technical Committees list
ASHRAE Technical Committees list
The technical expertise of ASHRAE is concentrated in its Technical Committees (TCs), Task Groups (TGs), and Technical Resource Groups (TRGs). Find a TC list here.
·ashrae.org·
ASHRAE Technical Committees list
Fogging disinfectants in Healthcare Facilities ~Association for Professionals in Infection Prevention (APIC), the Society for Healthcare Epidemiology of America (SHEA) and the Association for the Healthcare Environment (AHE)
Fogging disinfectants in Healthcare Facilities ~Association for Professionals in Infection Prevention (APIC), the Society for Healthcare Epidemiology of America (SHEA) and the Association for the Healthcare Environment (AHE)
***2011 {Importantly, C difficile spores. Zimek fogger used to disperse EPA-registered disinfectants. User instructions needed. Most surfaces in patient rooms are non-porous.
·shea-online.org·
Fogging disinfectants in Healthcare Facilities ~Association for Professionals in Infection Prevention (APIC), the Society for Healthcare Epidemiology of America (SHEA) and the Association for the Healthcare Environment (AHE)
Navy fogging -NRL Chemists’ Rapid Response Cleans Up
Navy fogging -NRL Chemists’ Rapid Response Cleans Up
“Quaternary ammonium compounds were the most sensible solution for large area shipboard use, because they can effectively deactivate the virus by destroying its protein membrane,” Wynne said. “There are other chemicals that can be used to deactivate the virus, but they would be more corrosively aggressive to a ship’s delicate ecosystem."
·www.nrl.navy.mil·
Navy fogging -NRL Chemists’ Rapid Response Cleans Up