https://thehillside.info/index.php?action=history&feed=atom&title=Ventilation_and_COVID-19
Ventilation and COVID-19 - Revision history
2026-05-08T13:30:07Z
Revision history for this page on the wiki
MediaWiki 1.43.5
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=6027&oldid=prev
Tobyvan: /* Transmission routes */ removed fomite from preferential route list
2021-08-19T12:56:21Z
<p><span class="autocomment">Transmission routes: </span> removed fomite from preferential route list</p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<tr class="diff-title" lang="en-GB">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:56, 19 August 2021</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l17">Line 17:</td>
<td colspan="2" class="diff-lineno">Line 17:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Droplet precautions, therefore, include standard precautions like PPE, hand washing and distancing, while airborne precautions include negative pressure isolation, respiratory protection, special exhaust or filtration regimes, etc.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Droplet precautions, therefore, include standard precautions like PPE, hand washing and distancing, while airborne precautions include negative pressure isolation, respiratory protection, special exhaust or filtration regimes, etc.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Diseases seldom obey only one mode of transmission (obligatory transmission) but often have preferences (preferential transmission) while occasionally exploiting circumstances which provide rare opportunities for transmission (opportunistic routes). SARS-COV-2 is understood to be '''preferentially droplet <del style="font-weight: bold; text-decoration: none;">and contact </del>spread''' <del style="font-weight: bold; text-decoration: none;">(a form of droplet spread where droplets can settle on fomites) </del>with opportunistic airborne spread possible in specific conditions, although an extensive outbreak review revealed no indication of airborne spread as defined for TB or measles<ref>https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations</ref>. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Diseases seldom obey only one mode of transmission (obligatory transmission) but often have preferences (preferential transmission) while occasionally exploiting circumstances which provide rare opportunities for transmission (opportunistic routes). SARS-COV-2 is understood to be '''preferentially droplet spread''' with opportunistic airborne spread possible in specific conditions, although an extensive outbreak review revealed no indication of airborne spread as defined for TB or measles<ref>https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations</ref>. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Airborne Transmission===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Airborne Transmission===</div></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=6007&oldid=prev
Tobyvan: /* Transmission routes */
2021-02-16T11:43:34Z
<p><span class="autocomment">Transmission routes</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 13:43, 16 February 2021</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l17">Line 17:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Droplet precautions, therefore, include standard precautions like PPE, hand washing and distancing, while airborne precautions include negative pressure isolation, respiratory protection, special exhaust or filtration regimes, etc.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Droplet precautions, therefore, include standard precautions like PPE, hand washing and distancing, while airborne precautions include negative pressure isolation, respiratory protection, special exhaust or filtration regimes, etc.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Diseases seldom obey only one mode of transmission (obligatory transmission) but often have preferences (preferential transmission) while occasionally exploiting circumstances which provide rare opportunities for transmission (opportunistic routes). SARS-COV-2 is understood to be '''preferentially droplet and contact spread''' (a form of droplet spread where droplets can settle on fomites) with <del style="font-weight: bold; text-decoration: none;">possible rare and </del>opportunistic airborne spread, although an extensive outbreak review revealed no indication of airborne spread<ref>https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations</ref>. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Diseases seldom obey only one mode of transmission (obligatory transmission) but often have preferences (preferential transmission) while occasionally exploiting circumstances which provide rare opportunities for transmission (opportunistic routes). SARS-COV-2 is understood to be '''preferentially droplet and contact spread''' (a form of droplet spread where droplets can settle on fomites) with opportunistic airborne spread <ins style="font-weight: bold; text-decoration: none;">possible in specific conditions</ins>, although an extensive outbreak review revealed no indication of airborne spread <ins style="font-weight: bold; text-decoration: none;">as defined for TB or measles</ins><ref>https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations</ref>. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Airborne Transmission===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Airborne Transmission===</div></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=5748&oldid=prev
Tobyvan: /* Amoy Gardens SARS Outbreak (2003)[18] */
2020-09-22T15:28:54Z
<p><span class="autocomment">Amoy Gardens SARS Outbreak (2003)[18]</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 17:28, 22 September 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l58">Line 58:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>====Amoy Gardens SARS Outbreak (2003)<ref name=":1">McKinney KR, Gong YY, Lewis TG. Environmental transmission of SARS at Amoy Gardens. ''J Environ Health''. 2006;68(9):26-52.</ref>====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>====Amoy Gardens SARS Outbreak (2003)<ref name=":1">McKinney KR, Gong YY, Lewis TG. Environmental transmission of SARS at Amoy Gardens. ''J Environ Health''. 2006;68(9):26-52.</ref>====</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Studies, which indicate the Amoy Gardens building's SARS outbreaks' transmission was via the airborne route<ref name=":1" />, commonly reference the prevailing wind between buildings. It should be noted that, since these buildings are about 60m apart the environmental dilution and concentration decay effects are so strong it is not feasible that an infectious dose persists at that range. Similarly, the possibility that air can commute out of one window and into another needs to account for these dilution effects before assumptions of transmission can be drawn. These studies do not sufficiently account for dilution, infectious doses and pathogen survival rates. A more feasible hypothesis is that the Amoy Gardens intra-building spread was through re-aerosolisation of contaminated waste water coming from the faulty plumbing system. Similar outbreaks have more recently been found<ref name=":2">Bhowmick, G.D., Dhar, D., Nath, D. et al. Coronavirus disease 2019 (COVID-19) outbreak: some serious consequences with urban and rural water cycle. npj Clean Water 3, 32 (2020). https://doi.org/10.1038/s41545-020-0079-1</ref>.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Studies, which indicate the Amoy Gardens building's SARS outbreaks' transmission was via the airborne route<ref name=":1" />, commonly reference the prevailing wind between buildings. It should be noted that, since these buildings are about 60m apart<ins style="font-weight: bold; text-decoration: none;">, </ins>the environmental dilution and concentration decay effects are so strong it is not feasible that an infectious dose persists at that range. Similarly, the possibility that air can commute out of one window and into another needs to account for these dilution effects before assumptions of transmission can be drawn. These studies do not sufficiently account for dilution, infectious doses and pathogen survival rates. A more feasible hypothesis is that the Amoy Gardens intra-building spread was through re-aerosolisation of contaminated waste water coming from the faulty plumbing system. Similar outbreaks have more recently been found<ref name=":2">Bhowmick, G.D., Dhar, D., Nath, D. et al. Coronavirus disease 2019 (COVID-19) outbreak: some serious consequences with urban and rural water cycle. npj Clean Water 3, 32 (2020). https://doi.org/10.1038/s41545-020-0079-1</ref><ins style="font-weight: bold; text-decoration: none;">. The re-aerosolisation from sanitary systems should be directly compared with long range oral-airborne transmission. The Amoy-Gardens transmission mode was most likely closer to large droplet transmission from toilets and waste outlets</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>====Other studies====</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>====Other studies====</div></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4967&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:28:19Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
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<col class="diff-marker" />
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:28, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l254">Line 254:</td>
<td colspan="2" class="diff-lineno">Line 254:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> <math>Q/n = 60 \times \bigl(A/n) </math></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> <math>Q/n = 60 \times \bigl(A/n) </math></div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> <math>Q<del style="font-weight: bold; text-decoration: none;">/n </del>= 60 \times \bigl(<del style="font-weight: bold; text-decoration: none;">A/n</del>) </math></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> <math><ins style="font-weight: bold; text-decoration: none;">\therefore </ins>Q = 60 \times \bigl(<ins style="font-weight: bold; text-decoration: none;">m^2 per person</ins>) </math></div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4966&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:24:55Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:24, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l253">Line 253:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"> <math>Q/n = 60 \times \bigl(A/n) </math></ins></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> <math>Q/n = 60 \times \bigl(A/n) </math></div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div> <math>Q/n = 60 \times \bigl(A/n) </math></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Assuming face masks reduce transmission by 40%, ventilation rates of '''38''' <math>L/s\cdot person</math> would be required to control airborne transmission. This sounds like a lot until the social distancing and decongestion measures required for droplet precautions are applied. under these conditions this equates to only '''4.23''' <math>L/s\cdot m^2</math> or between 4 and 5 ACH (assuming a 3.2m ceiling height). This should be easily achievable for naturally ventilated spaces and could be verified by measuring average indoor CO<sub>2</sub> concentrations no greater than '''170 PPM''' above outdoor. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Assuming face masks reduce transmission by 40%, ventilation rates of '''38''' <math>L/s\cdot person</math> would be required to control airborne transmission. This sounds like a lot until the social distancing and decongestion measures required for droplet precautions are applied. under these conditions this equates to only '''4.23''' <math>L/s\cdot m^2</math> or between 4 and 5 ACH (assuming a 3.2m ceiling height). This should be easily achievable for naturally ventilated spaces and could be verified by measuring average indoor CO<sub>2</sub> concentrations no greater than '''170 PPM''' above outdoor.</div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Conclusion==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Conclusion==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Therefore, assuming ventilation systems in South Africa have been designed in accordance with the IUSS guidance, there should be little reason to change their configuration or pressurization unless general areas are repurposed as airborne precaution rooms. Risk assessments should be conducted for ICUs and COVID-19 wards immediately adjacent to public waiting areas or other high traffic areas, with corrective actions including but not limited to reducing occupancy times and rates for these areas and adjusting distancing rules. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Therefore, assuming ventilation systems in South Africa have been designed in accordance with the IUSS guidance, there should be little reason to change their configuration or pressurization unless general areas are repurposed as airborne precaution rooms. Risk assessments should be conducted for ICUs and COVID-19 wards immediately adjacent to public waiting areas or other high traffic areas, with corrective actions including but not limited to reducing occupancy times and rates for these areas and adjusting distancing rules. </div></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4965&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:23:46Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en-GB">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:23, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l253">Line 253:</td>
<td colspan="2" class="diff-lineno">Line 253:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> <math>Q <del style="font-weight: bold; text-decoration: none;">\div </del>n = 60 \times \bigl(A/n) </math></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> <math>Q<ins style="font-weight: bold; text-decoration: none;">/</ins>n = 60 \times \bigl(A/n) </math></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4964&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:23:00Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en-GB">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:23, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l253">Line 253:</td>
<td colspan="2" class="diff-lineno">Line 253:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> <math>Q = 60 \times \bigl(A/n) </math></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> <math>Q <ins style="font-weight: bold; text-decoration: none;">\div n </ins>= 60 \times \bigl(A/n) </math></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4963&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:21:57Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en-GB">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:21, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l253">Line 253:</td>
<td colspan="2" class="diff-lineno">Line 253:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> <math>Q = 60 \<del style="font-weight: bold; text-decoration: none;">div </del>\bigl(A/n) </math></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> <math>Q = 60 \<ins style="font-weight: bold; text-decoration: none;">times </ins>\bigl(A/n) </math></div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4962&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:17:36Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
<table style="background-color: #fff; color: #202122;" data-mw="interface">
<col class="diff-marker" />
<col class="diff-content" />
<col class="diff-marker" />
<col class="diff-content" />
<tr class="diff-title" lang="en-GB">
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:17, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l253">Line 253:</td>
<td colspan="2" class="diff-lineno">Line 253:</td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To maintain a personal risk below 1% the following correction is advised:</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;"> </ins><math>Q = 60 \div \bigl(A/n) </math></div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><math>Q = 60 \div \bigl(A/n) </math></div></td><td colspan="2" class="diff-side-added"></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div> </div></td><td colspan="2" class="diff-side-added"></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
</table>
Tobyvan
https://thehillside.info/index.php?title=Ventilation_and_COVID-19&diff=4961&oldid=prev
Tobyvan: /* Airborne precautions for settings with uncertain or high residual risk */
2020-08-07T12:17:06Z
<p><span class="autocomment">Airborne precautions for settings with uncertain or high residual risk</span></p>
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<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">← Older revision</td>
<td colspan="2" style="background-color: #fff; color: #202122; text-align: center;">Revision as of 14:17, 7 August 2020</td>
</tr><tr><td colspan="2" class="diff-lineno" id="mw-diff-left-l258">Line 258:</td>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Where '''Q''' is the ventilation rate <math>(L/s\cdot m^2)</math>, '''A''' is the floor area <math>(m^2)</math> and n is the maximum number of people in the space.<br />Air changes per hour (ACH) can be estimated with <math>ACH = Q \times 3.6 \div h </math>, where <math>h</math> is the ceiling height.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Assuming face masks reduce transmission by 40%, ventilation rates of '''38''' <math>L/s\cdot person</math> would be required to control airborne transmission. This sounds like a lot until the social distancing and decongestion measures required for droplet precautions are applied. under these conditions this equates to only '''4.23''' <math>L/s\cdot m^2</math> or between 4 and 5 ACH (assuming a 3.2m ceiling height). This should be easily achievable for naturally ventilated spaces and could be verified by measuring average indoor CO<sub>2</sub> <del style="font-weight: bold; text-decoration: none;">levels </del>no greater than '''170 PPM''' above outdoor <del style="font-weight: bold; text-decoration: none;">levels</del>. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Assuming face masks reduce transmission by 40%, ventilation rates of '''38''' <math>L/s\cdot person</math> would be required to control airborne transmission. This sounds like a lot until the social distancing and decongestion measures required for droplet precautions are applied. under these conditions this equates to only '''4.23''' <math>L/s\cdot m^2</math> or between 4 and 5 ACH (assuming a 3.2m ceiling height). This should be easily achievable for naturally ventilated spaces and could be verified by measuring average indoor CO<sub>2</sub> <ins style="font-weight: bold; text-decoration: none;">concentrations </ins>no greater than '''170 PPM''' above outdoor. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Conclusion==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Conclusion==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Therefore, assuming ventilation systems in South Africa have been designed in accordance with the IUSS guidance, there should be little reason to change their configuration or pressurization unless general areas are repurposed as airborne precaution rooms. Risk assessments should be conducted for ICUs and COVID-19 wards immediately adjacent to public waiting areas or other high traffic areas, with corrective actions including but not limited to reducing occupancy times and rates for these areas and adjusting distancing rules. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Therefore, assuming ventilation systems in South Africa have been designed in accordance with the IUSS guidance, there should be little reason to change their configuration or pressurization unless general areas are repurposed as airborne precaution rooms. Risk assessments should be conducted for ICUs and COVID-19 wards immediately adjacent to public waiting areas or other high traffic areas, with corrective actions including but not limited to reducing occupancy times and rates for these areas and adjusting distancing rules. </div></td></tr>
</table>
Tobyvan