{"id":2083,"date":"2021-12-29T19:10:00","date_gmt":"2021-12-29T18:10:00","guid":{"rendered":"https:\/\/www.devatec.com\/?p=2083"},"modified":"2023-03-24T12:14:33","modified_gmt":"2023-03-24T11:14:33","slug":"humidification-fights-against-bioaerosol-infectivity","status":"publish","type":"post","link":"https:\/\/www.devatec.com\/en\/humidification-fights-against-bioaerosol-infectivity\/","title":{"rendered":"Humidification fights against bioaerosol infectivity"},"content":{"rendered":"\n

Relative humidity between 40% and 60% is ideal
\u2022 To reduce bioaerosol droplet evaporation,
\u2022 To reduce infection transmission,
\u2022 To reduce bioaerosol infectivity<\/p>\n\n\n\n

BARRIER GESTURES<\/h4>\n\n\n\n

Everybody knows the barrier gestures: No face touching, hand washing, disposable tissue using, mask
wearing, cough\/sneeze in the elbow. Mask wearing is very important when people are in public places
or supermarkets. But it is not always possible to wear a mask at home in family, in offices. Controlled
relative humidity between 40% and 60% is ideal to reduce the contamination by bioaerosols.<\/p>\n\n\n\n

SURGICAL FACE MASK EFFICIENCY<\/strong> (1)<\/p>\n\n\n\n

\"\"
When indoor humidity ratio is around 7 – 10 g\/kg (relative humidity 40%-60%) (2)(3),
the respiratory infection effects decrease.<\/figcaption><\/figure>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Bioaerosol transmission<\/h2>\n\n\n\n

At this time, evidences accepted scientifically suggest that a controlled relative humidity can reduce
the transmission of infectious agents by bioaerosols. (5)<\/p>\n\n\n\n

What are bioaerosols?<\/h4>\n\n\n\n

Bioaerosols are airborne biological particles derived from virus, bacteria, fungi, protozoa, algae,
mites, plants, insects and their by-products, fragments and cell mass components (11)<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

Exhaled bioaerosols<\/strong><\/p>\n\n\n\n

\"\"<\/figure>
\n

They fall 1.5 -2.0 m height:<\/p>\n\n\n\n

    \n
  • in less of 6 seconds if diameter > 1mm,<\/li>\n\n\n\n
  • in ~ 6 seconds if diameter ~ 100 \u03bcm,<\/li>\n\n\n\n
  • in ~ 8 minutes if diameter ~ 10 \u03bcm,<\/li>\n\n\n\n
  • in ~ 1.5 hours if diameter ~ 3 \u03bcm,<\/li>\n\n\n\n
  • in ~ 12 hours if diameter ~ 1 \u03bcm,<\/li>\n\n\n\n
  • in ~ 41 hours if diameter ~ 0.5 \u03bcm. (4) (5)(7)
    Note: 87% of exhaled bioaerosols are < 1 \u03bcm. (6)<\/li>\n<\/ul>\n\n\n\n

    <\/p>\n<\/div><\/div>\n\n\n\n

    Bioaerosols emited by coughing or sneezing<\/strong><\/p>\n\n\n\n

    \"\"<\/figure>\n\n\n\n

    Correct relative humidity reduces bioaerosol transmission<\/h2>\n\n\n\n

    Maintaining indoor humidity ratio around 7 – 10 g\/kg (relative humidity 40%-60%) helps<\/p>\n\n\n\n

    To reduce the droplet evaporation process<\/strong> (5): large droplets are less rapidly changed into droplet
    nuclei.<\/p>\n\n\n\n

    To reduce the transmission efficiency of virus airbornes:<\/p>\n\n\n\n

    \n

    \u201cAt 20\u00baC (dashed line), transmission efficiency is
    highest at low RH, when influenza virions in an aerosol
    are relatively stable, and desiccation of exhaled respiratory droplets produces droplet nuclei.
    Transmission is diminished at intermediate RH when
    virus particles are relatively unstable, but improves in
    parallel with influenza virus stability at higher humidities.
    At high RH, evaporation from exhaled particles is
    limited, respiratory droplets settle out of the air, and
    transmission is blocked\u201d (8)<\/p>\n<\/div>

    \"\"<\/figure><\/div>\n\n\n\n

    To reduce the bioaerosols infectivity:<\/strong><\/p>\n\n\n\n

    \n
    \"\"<\/figure>\n\n\n\n
    \"\"<\/figure>\n\n\n\n
    \"\"<\/figure>\n\n\n\n
    \"\"<\/figure>\n
    \u201cAt constant temperature (20\u00baC) high humidity reduces the infectivity of influenza.\u201d (9)<\/figcaption><\/figure>\n\n\n\n
    Sources:<\/strong>\n (1) COVID-19: Why we should ware all mask, Sui Huang.\n (2) C. Mike Scofiel, P.E., and Elia Sterling. Dry Climate evaporative cooling with refrigeration backup, ASHRAE Journal 1992\n (3) 2016 ASHRAE HVAC Systems and Equipment Handbook, Chap 22. Humidfiers\n (4) Wells, W. F., On Air-borne Infection. Study II. Droplets and Droplet Nuclei. Journal article: American Journal of Hygiene 1934 Vol.20 pp.611-18\n (5) ASHRAE Position Document on Airborne Infectious Diseases Approved by ASHRAE Board of Directors April 14 , 2020\n (6)Fabian P, McDevitt JJ, DeHaan WH, Fung ROP, Cowling BJ, et al. (2008) Influenza Virus in Human Exhaled Breath: An Observational Study. PLoS ONE\n 3(7):e2691. doi:10.1371\/journal.pone.0002691\n (7) Natural Ventilation for Infection Control in Health-Care Settings Editors: James Atkinson, Yves Chartier, Carmen L\u00facia Pessoa-Silva, Paul Jensen,\n Yuguo Li, and Wing-Hong Seto. Geneva: World Health Organization; 2009.\n (8) Lowen AC, Mubareka S, Steel J, Palese P (2007) Influenza virus transmission is dependent on relative humidity and temperature. PLoS Pathog 3(10):\n e151. doi:10. 1371\/journal.ppat.0030151\n (9) Noti JD et. al, High Humidity Leads to Loss of Infections Influenza Virus from Simulated Coughs, PLoS ONE 8(2): e57485, 2013\n (10) Blausen.com staff (2014). \"Medical gallery of Blausen Medical 2014\".\n (11) 2017 ASHRAE Fundamentals Handbook, Chap 10. Indoor environment health\n Author<\/strong>: P.E. David, Pharmacist and HVAC Specialist at Armstrong International<\/pre>\n","protected":false},"excerpt":{"rendered":"
    Relative humidity between 40% and 60% is ideal\u2022 To reduce bioaerosol droplet evaporation,\u2022 To reduce infection transmission,\u2022 To reduce bioaerosol infectivity BARRIER GESTURES Everybody knows the barrier gestures: No face touching, hand washing, disposable tissue using, maskwearing, cough\/sneeze in the elbow. Mask wearing is very important when people are in public placesor supermarkets. But it is not always possible to wear a mask at home in family, in offices. Controlledrelative humidity between 40% and 60% is ideal to reduce the contamination by bioaerosols. SURGICAL FACE MASK EFFICIENCY (1) Bioaerosol transmission At this time, evidences accepted scientifically suggest that a controlled relative humidity can reducethe transmission of infectious agents by bioaerosols. (5) What are bioaerosols? Bioaerosols are airborne biological particles derived from virus, bacteria, fungi, protozoa, algae,mites, plants, insects and their by-products, fragments and cell mass components (11) Exhaled bioaerosols Bioaerosols emited by coughing or sneezing Correct relative humidity reduces bioaerosol transmission Maintaining indoor humidity ratio around 7 – 10 g\/kg (relative humidity 40%-60%) helps To reduce the droplet evaporation process (5): large droplets are less rapidly changed into dropletnuclei. To reduce the transmission efficiency of virus airbornes: \u201cAt 20\u00baC (dashed line), transmission efficiency ishighest at low RH, when influenza virions in an aerosolare relatively stable, and desiccation of exhaled respiratory droplets produces droplet nuclei.Transmission is diminished at intermediate RH whenvirus particles are relatively unstable, but improves inparallel with influenza virus stability at higher humidities.At high RH, evaporation from exhaled particles islimited, respiratory droplets settle out of the air, andtransmission is blocked\u201d (8) To reduce the bioaerosols infectivity: Sources: (1) COVID-19: Why we should ware all mask, Sui Huang. (2) C. Mike Scofiel, P.E., and Elia Sterling. Dry Climate evaporative cooling with refrigeration backup, ASHRAE Journal 1992 (3) 2016 ASHRAE HVAC Systems and Equipment Handbook, Chap 22. Humidfiers (4) Wells, W. F., On Air-borne Infection. Study II. Droplets and Droplet Nuclei. Journal article: American Journal of Hygiene 1934 Vol.20 pp.611-18 (5) ASHRAE Position Document on Airborne Infectious Diseases Approved by ASHRAE Board of Directors April 14 , 2020 (6)Fabian P, McDevitt JJ, DeHaan WH, Fung ROP, Cowling BJ, et al. (2008) Influenza Virus in Human Exhaled Breath: An Observational Study. PLoS ONE 3(7):e2691. doi:10.1371\/journal.pone.0002691 (7) Natural Ventilation for Infection Control in Health-Care Settings Editors: James Atkinson, Yves Chartier, Carmen L\u00facia Pessoa-Silva, Paul Jensen, Yuguo Li, and Wing-Hong Seto. Geneva: World Health Organization; 2009. (8) Lowen AC, Mubareka S, Steel J, Palese P (2007) Influenza virus transmission is dependent on relative humidity and temperature. PLoS Pathog 3(10): e151. doi:10. 1371\/journal.ppat.0030151 (9) Noti JD et. al, High Humidity Leads to Loss of Infections Influenza Virus from Simulated Coughs, PLoS ONE 8(2): e57485, 2013 (10) Blausen.com staff (2014). “Medical gallery of Blausen Medical 2014”. (11) 2017 ASHRAE Fundamentals Handbook, Chap 10. Indoor environment health Author: P.E. David, Pharmacist and HVAC Specialist at Armstrong International<\/p>\n","protected":false},"author":7,"featured_media":794,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_seopress_robots_primary_cat":"","_seopress_titles_title":"","_seopress_titles_desc":"","_seopress_robots_index":"","footnotes":""},"categories":[71],"tags":[],"class_list":["post-2083","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-humidification-en"],"_links":{"self":[{"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/posts\/2083","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/comments?post=2083"}],"version-history":[{"count":0,"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/posts\/2083\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/media\/794"}],"wp:attachment":[{"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/media?parent=2083"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/categories?post=2083"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.devatec.com\/en\/wp-json\/wp\/v2\/tags?post=2083"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}