In the published article, there were several errors made in the text:
Two definitions were not properly spaced.
A correction has been made to Inhalation equations, Paragraph 3. The definition sentences previously stated:
“NT = number of occupants in the space t = occupancy time after the exposed group including the infector enter the space”
The corrected definition sentences appear below:
“NT = number of occupants in the space
t = occupancy time after the exposed group including the infector enter the space”
The definitions of ro and P are not provided.
A correction has been made to the Infection Equations following Equation 14.
The definitions to be added after Equation 14 appear below:where
= reproduction rate, the average number of secondary transmissions per infectious person
= disease prevalence, the fraction of the population that is shedding infectious aerosols at the rate used in calculating dose, D
Missing words, small p and wrong equation number.
A correction has been made to Designing HVAC Systems, Paragraph 1, missing phrase introducing the equation; variable p should be cap P; Equation 14 should be Equation 15. This sentence and the following equation previously stated:
… for the average infectious period of the index.
The corrected variable name and equation number appear below:
“for the average infectious period of the index, the disease prevalence at the beginning then is”
A variable definition missing.
A correction has been made to Designing HVAC systems, Paragraph 5. This sentence previously stated:
“…maximum reproduction number either in the setting…”
The corrected sentence appears below:
“…maximum reproduction number ro either in the setting…”
The caption of Table 2 requires more information. The caption previously was: Table 2 Outdoor air exposure estimates”
The corrected Table 2 caption appears below:
“Table 2 Occupancy experience example input data for four settings”
There was an error in the below factor, which originally stated: “then by a factor (i.e. 1.127) to obtain.” The corrected factor appears below
“then by a factor (i.e. 0.898) to obtain.”
The below sub-section name should have been a higher level:
A correction has been made to Design of HVAC systems, Equal reproduction and Equal reproduction and local prevalence.
The equation number in text is incorrect
A correction has been made to Designing HVAC systems, Equal reproduction, Paragraph 8. This sentence previously stated:
“…using Equation 15 where no = 1.”
The corrected sentence appears below:
“…using Equation 14 where:
The equation number and lack of capitalization for p is incorrect.
A correction has been made to Designing HVAC systemsOccupancy experience example. The equation number previously and variable P was:
The corrected equation number and variable P appears below:
The sub-sub-section title for Recirculation and filter flow was place on too high a level and should have been downsized.
The equation number was incorrect:
A correction has been made to Occupancy experience example. The equation number previously was:
The corrected equation number appears below:
The caption for Table 3 needed clarification. The caption for Table 3 as published was: “Determining the filter efficiency and the flow required”
TABLE 3
| Setting | ASHRAE 62 ventilation | Disease | Occupant metabolic | Exposure/week | ro = 3.29 infections for ASHRAE 62 ventilation | Ventilation with filtered recirculation added for ro =2.52 infections | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| outside air | Prevalence | quanta/ | Breathing | hrs/p | infections | % | Same | virion-free | outside air | recirc air | |||
| Qp | for 4 days | hour | QB | percent | air req'd | saving | H = 0.62 | ||||||
| cfm/p | p | qn | btu/hr | Met | cfm/p | infections | cfm/P | cfm/p | cfm/p | ||||
| School | 22.3 | 3% | 12 | 323 | 0.83 | 0.25 | 17.1 | 2.22 | 67.3% | 1.49 | 33.5 | 18.1 | |
| Restaurant | 13.1 | 3% | 12 | 485 | 1.24 | 0.37 | 2.3 | 0.77 | 23.4% | 0.70 | 14.5 | 2.3 | |
| Supermarket | 64.5 | 3% | 12 | 460 | 1.18 | 0.35 | 1.7 | 0.11 | 3.4% | 0.12 | 59.9 | 4.6 | |
| Gym | 39.8 | 3% | 12 | 740 | 1.9 | 0.57 | 1.1 | 0.20 | 5.9% | 0.21 | 37.9 | 1.9 | |
Determining the filter efficiency and flow required.
The Table 3 caption as corrected appears below:
“Table 3 Occupancy experience example recirculation flow requirements using Merv 13 filters to achieve a combined reproduction rate ro of 2.5 for the four settings.”
Table 3 had too many decimal places and had to be expanded to include the metabolic and breathing rates that were used in the Occupancy experience example. The corrected Table 3 and it’s caption appear below:
The caption of Table 4 needed more information, and some figure were incorrect. The corrected table caption appears below:
TABLE 4
| P | Typical | Outside air ventilation & occupancy - ASHRAE Standard 62 | Infection parameters in typical setting & exposure time | Ventilation required ro=2.5 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nd | NT | Infection | Qp | Qf | ||||||||
| Ceiling | occupants | Rp | Ra | Qpo | number | prevalence | Ventilation | occupancy | Qpo+hQf | unfiltered | ||
| height | per | cfm per | cfm/ft2 | L/s-p | of | P | Effectiveness | filter | time | clean air | recirc air | |
| ft | 1000 ft2 | person | outdoor air | occupants | % | VE | eff | hours | L/s-p | L/s-p | ||
| Aircraft cabin, narrow body | 5.8 | 190 | 7.5 | 0 | 3.5 | 150 | 3% | 0.8 | 0.995 | 3 | 9.9 | 6.4 |
| Aircraft cabin, wide body | 6.7 | 136 | 10 | 0 | 4.7 | 320 | 3% | 1 | 0.995 | 10 | 26.7 | 22.1 |
| Auditorium, theater | 20 | 150 | 5 | 0.06 | 2.6 | 100 | 3% | 0.8 | 0.5 | 3 | 9.6 | 14.0 |
| Bar, cocktail lounge | 9 | 100 | 7.5 | 0.18 | 4.4 | 60 | 3% | 0.8 | 0.5 | 3 | 9.7 | 10.6 |
| Classroom 5-8 | 12 | 25 | 10 | 0.12 | 7.0 | 30 | 3% | 1 | 0.5 | 6 | 15.4 | 16.8 |
| Classroom 9+ | 12 | 35 | 10 | 0.12 | 6.3 | 30 | 3% | 1 | 0.5 | 6 | 15.6 | 18.5 |
| Day care (through age 4)- residence setting | 8 | 25 | 10 | 0.18 | 8.1 | 10 | 3% | 1 | 0.5 | 8 | 21.1 | 25.9 |
| Gambling casino | 9 | 120 | 7.5 | 0.18 | 4.3 | 400 | 3% | 0.8 | 0.5 | 6 | 20.0 | 31.4 |
| Lecture classroom | 12 | 65 | 10 | 0.06 | 5.2 | 30 | 3% | 0.8 | 0.5 | 6 | 19.8 | 29.2 |
| Lecture hall | 20 | 150 | 7.5 | 0.06 | 3.7 | 100 | 3% | 0.8 | 0.5 | 2 | 5.9 | 4.4 |
| Mall, common areas | 18 | 40 | 7.5 | 0.06 | 4.3 | 150 | 3% | 1 | 0.5 | 3 | 6.6 | 4.7 |
| Music/theater/dance | 12 | 35 | 10 | 0.06 | 5.5 | 50 | 3% | 1 | 0.5 | 3 | 7.0 | 2.9 |
| Office | 9 | 5 | 5 | 0.06 | 8.0 | 80 | 3% | 1 | 0.5 | 8 | 19.4 | 22.8 |
| Restaurant | 9 | 70 | 7.5 | 0.18 | 4.8 | 50 | 3% | 1 | 0.5 | 2 | 4.8 | 0.0 |
| Retail sales store | 18 | 15 | 7.5 | 0.12 | 7.3 | 25 | 3% | 0.8 | 0.5 | 2 | 7.3 | 0.0 |
| Spectator area (Maple Leaf Gardens) | 55 | 150 | 10 | 0.06 | 4.9 | 5,000 | 3% | 1 | 0.5 | 4 | 9.9 | 10.0 |
Compilation of Figure 5 using Equation 18 and national prevalence P = 0.03.
The caption of Table 5 required clarification and some values in the Filter Eff column were incorrect. The corrected table caption appears below:
TABLE 5
| Typical | Outside air ventilation from ASHRAE Standard 62 | Infection parameters in typical setting & exposure time | Ventilation required ro=2.5 | occupant experience | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nd | NT | Infection | Qp | Qf | Qoe | Qp | ||||||||
| Ceiling | occupants | Rp | Ra | Qpo | number | prevalence | Ventilation | occupancy | Qpo+hQf | unfiltered | additional | Qpo+hQf+Qoe | ||
| height | per | cfm per | cfm/ft2 | L/s-p | of | P | Effectiveness | filter | time | clean air | recirc air | clean air | clean air | |
| ft | 1000 ft2 | person | outdoor air | occupants | % | VE | eff | hours | L/s-p | L/s-p | L/s-p | L/s-p | ||
| Aircraft cabin, narrow body | 5.8 | 190 | 7.5 | 0 | 3.5 | 150 | 0.03 | 0.8 | 0.995 | 3 | 10.3 | 6.8 | 0.03 | 10.4 |
| Aircraft cabin, wide body | 6.7 | 136 | 10 | 0 | 4.7 | 320 | 0.03 | 1 | 0.995 | 10 | 27.7 | 23.1 | 0.03 | 27.7 |
| Auditorium, theater | 20 | 150 | 5 | 0.06 | 2.6 | 100 | 0.03 | 0.8 | 0.5 | 3 | 10.0 | 14.8 | 0.003 | 10.0 |
| Bar, cocktail lounge | 9 | 100 | 7.5 | 0.18 | 4.4 | 60 | 0.03 | 0.8 | 0.5 | 3 | 10.1 | 11.5 | ||
| Classroom 5-8 | 12 | 25 | 10 | 0.12 | 7 | 30 | 0.03 | 1 | 0.5 | 6 | 16.0 | 18.1 | 8.5 | 24.5 |
| Classroom 9+ | 12 | 35 | 10 | 0.12 | 6.3 | 30 | 0.03 | 1 | 0.5 | 6 | 16.2 | 19.7 | 8.5 | 24.7 |
| Day care (through age 4)- residence setting | 8 | 25 | 10 | 0.18 | 8.1 | 10 | 0.03 | 1 | 0.5 | 8 | 21.9 | 27.6 | ||
| Gambling casino | 9 | 120 | 7.5 | 0.18 | 4.3 | 400 | 0.03 | 0.8 | 0.5 | 6 | 20.7 | 32.9 | ||
| Lecture classroom | 12 | 65 | 10 | 0.06 | 5.2 | 30 | 0.03 | 0.8 | 0.5 | 6 | 20.6 | 30.8 | ||
| Lecture hall | 20 | 150 | 7.5 | 0.06 | 3.7 | 100 | 0.03 | 0.8 | 0.5 | 2 | 6.2 | 5.0 | ||
| Mall, common areas | 18 | 40 | 7.5 | 0.06 | 4.3 | 150 | 0.03 | 1 | 0.5 | 3 | 6.9 | 5.3 | ||
| Music/theater/dance | 12 | 35 | 10 | 0.06 | 5.5 | 50 | 0.03 | 1 | 0.5 | 3 | 7.3 | 3.6 | ||
| Office | 9 | 5 | 5 | 0.06 | 8 | 80 | 0.03 | 1 | 0.5 | 8 | 20.3 | 24.6 | 0.11 | 20.4 |
| Restaurant | 9 | 70 | 7.5 | 0.18 | 4.8 | 50 | 0.03 | 1 | 0.5 | 2 | 5.0 | 0.5 | 6.4 | 11.4 |
| Retail sales store | 18 | 15 | 7.5 | 0.12 | 7.3 | 25 | 0.03 | 0.8 | 0.5 | 2 | 7.3 | 0.0 | ||
| Spectator area (Maple Leaf Gardens) | 55 | 150 | 10 | 0.06 | 4.9 | 5000 | 0.03 | 1 | 0.5 | 4 | 10.4 | 10.9 | ||
Compilation of Figure 6 using Equation 19 and a national prevalence P = 0.03.
A variable name was incorrect and the equation number is missing.
A correction has been made to Designing HVAC systems,Equal reproduction example,
The denominator variable should be cap P and the equation number is (19). The corrected equation appears below:
There was an error missing equation number.
A correction has been made to Designing HVAC systems,Equal reproduction and local prevalence example
The equation as it now stands
The equation corrected
The caption of Table 6 needed more information, and some of the figures presented were inaccurate. The corrected table caption appears below:
TABLE 6
| Typical | Outdoor air and occupancy from ASHRAE Standard 62 | Infection parameters | Ventilation required ro=2.5 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Nd | NT | Qp | Qf | |||||||||
| Ceiling | occupants | Rp | Ra | Qpo | number | Infection | Ventilation | occupancy | Qpo+hQf | unfiltered | ||
| height | per | cfm per | cfm/ft2 | L/s-p | of | prevalence | Effectiveness | filter | time | clean air | recirc air | |
| ft | 1000 ft2 | person | outdoor air | occupants | P | VE | eff | hours | L/s-p | L/s-p | ||
| Aircraft cabin, narrow body | 5.8 | 190 | 7.5 | 0 | 3.5 | 150 | 0.67% | 0.8 | 0.995 | 3 | 10.1 | 6.6 |
| Aircraft cabin, wide body | 6.7 | 136 | 10 | 0 | 4.7 | 320 | 0.31% | 1 | 0.995 | 10 | 27.5 | 22.9 |
| Auditorium, theater | 20 | 150 | 5 | 0.06 | 2.6 | 100 | 1.00% | 0.8 | 0.5 | 3 | 9.7 | 14.3 |
| Bar, cocktail lounge | 9 | 100 | 7.5 | 0.18 | 4.4 | 60 | 1.67% | 0.8 | 0.5 | 3 | 9.7 | 10.6 |
| Classroom 5-8 | 12 | 25 | 10 | 0.12 | 7 | 30 | 3.33% | 1 | 0.5 | 6 | 14.7 | 15.5 |
| Classroom 9+ | 12 | 35 | 10 | 0.12 | 6.3 | 30 | 3.33% | 1 | 0.5 | 6 | 14.9 | 17.2 |
| Day care (through age 4)- residence setting | 8 | 25 | 10 | 0.18 | 8.1 | 10 | 10.00% | 1 | 0.5 | 8 | 16.8 | 17.3 |
| Gambling casino | 9 | 120 | 7.5 | 0.18 | 4.3 | 400 | 0.25% | 0.8 | 0.5 | 6 | 20.6 | 32.7 |
| Lecture classroom | 12 | 65 | 10 | 0.06 | 5.2 | 30 | 3.33% | 0.8 | 0.5 | 6 | 19.0 | 27.6 |
| Lecture hall | 20 | 150 | 7.5 | 0.06 | 3.7 | 100 | 1.00% | 0.8 | 0.5 | 2 | 6.0 | 4.6 |
| Mall, common areas | 18 | 40 | 7.5 | 0.06 | 4.3 | 150 | 0.67% | 1 | 0.5 | 3 | 6.8 | 5.1 |
| Music/theater/dance | 12 | 35 | 10 | 0.06 | 5.5 | 50 | 2.00% | 1 | 0.5 | 3 | 6.9 | 2.8 |
| Office | 9 | 5 | 5 | 0.06 | 8 | 80 | 1.25% | 1 | 0.5 | 8 | 19.6 | 23.2 |
| Restaurant | 9 | 70 | 7.5 | 0.18 | 4.8 | 50 | 2.00% | 1 | 0.5 | 2 | 4.8 | 0.0 |
| Retail sales store | 18 | 15 | 7.5 | 0.12 | 7.3 | 25 | 4.00% | 0.8 | 0.5 | 2 | 7.3 | 0.0 |
| Spectator area (Maple Leaf Gardens) | 55 | 150 | 10 | 0.06 | 4.9 | 5000 | 0.02% | 1 | 0.5 | 4 | 10.3 | 10.8 |
Compilation of Figure 7 using Equation 20 and local prevalence P = 1/NT for various settings for a reproduction rate ro = 2.5
The caption of Figure 5, 6 and 7 required additional detail. The corrected titles appear below:
Figure 5 Equal reproduction example using Equation 18 and national prevalence P = 0.03 for ventilation designed for ro = 2.5.
Figure 6 Equal reproduction example using the Wells-Riley approximation Equation 19 and national prevalence P = 0.03 for ventilation designed for reproduction ro = 2.5.
Figure 7 Equal reproduction example ventilation requirements for various settings to achieve ro = 2.5 using Equation 20, the data in Table 6 and local prevalence P = 1/NT (Equation 15).
The references to Tables 4, 5, Figure 5 and Figure 6 were missing. A corrections have been made to
The missing sentence below has been added to Designing HVAC systems,Equal reproduction example. :
“Equation 18 is used in calculating the recirculation flow requirements shown in Table 4 and Figure 5 for the various settings.”
And a correction has been made to the section Occupancy experience example. The figure and table reference previously was:
Figure 5; Table 4
The corrected reference appears below:
Figure 6; Table 5
The paragraph heading Occupancy Experience was incorrectly located.
A correction has been made to Occupancy Experience. The heading was previously before “This procedure sets a national….” and has been move to before “During COVID-19 Linka et al.
The derivation of Equation 20 was not fully explained.
A correction has been made to missing equations to explain the derivation of Equation 20.
The missing equations follow.
The possibility of zero infection follows a Poisson distribution:
For zero infection, x = 0
Probability of zero infections
Probability of infection for susceptible individual:
Risk for occupant i:
Total risk for all occupants:
Total risk for all occupants assuming a perfectly mixed volume:
Lambda is the quantity of the statistical unit inhaled for ith individual over time:
For the transient case, the virus dose is:
The reproduction number shows the number of infections from an infector, no = 1:
For steady state case t > 5 air changes:
In terms of quanta:
You get the Wells-Riley equation:
(20)
Extra clarification was need in the section Occupancy experience, following “…in that setting.
The additional sentence is: “Steady state occupancies only are considered ”
Clarification was needed in the section Equal reproduction, following “and transient”
The below was added: “(leaving or entering)”.
Statements
Publisher’s note
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.
Summary
Keywords
respiratory infections, HVAC filtration, infectious aerosols, Wells-Riley, COVID-19, infection reproduction rate, energy, ventilation standards
Citation
Walkinshaw DS and Horstman RH (2025) Corrigendum: Covid 19 and beyond: a procedure for HVAC systems to address infectious aerosol illness transmission. Front. Built Environ. 10:1487320. doi: 10.3389/fbuil.2024.1487320
Received
27 August 2024
Accepted
10 September 2024
Published
20 January 2025
Volume
10 - 2024
Edited and reviewed by
Ali Ghahramani, National University of Singapore, Singapore
Updates
Copyright
© 2025 Walkinshaw and Horstman.
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: Douglas Stuart Walkinshaw, dsw@indoorair.ca
Disclaimer
All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.