Irish Government Finally Recognises Importance of Indoor Ventilation
Following several communications with HSE, EAM Group are pleased to announce that the Health Protection Surveillance Centre (HPSC) have released a guidance document for commercial and public buildings (non-healthcare buildings) in relation to the importance of ventilation in indoor crowded spaces. They have now associated ventilation with increased SARS-CoV-2 transmission, examples are as follows:
- Out of 318 outbreaks (classified as 3 or more cases in a single setting) examined in China, only 1 could be traced back to transmission in an outdoor space.
- In Japan, a preprint article by Nishiura et al examined 110 cases and found that a primary case is 20 times more likely to transmit SARS-CoV-2 in a closed environment than in an open-air environment.
- 6 studies specific to SARS-CoV-2: One of these studies examined an outbreak in a Chinese restaurant. The authors concluded that the strong airflow created by the individual air conditioning unit, combined with low ventilation rates due to lack of outdoor air supply, and overcrowding, led to the outbreak of COVID-19 in 3 non-associated families.
- Poor ventilation was also associated with an outbreak on a 100-minute bus ride, during which 23 out of 67 passengers were infected from a single index case. The bus used a recirculating air-conditioning system. Apart from the passenger sitting next to the index case, none of the passengers sitting next to windows with air-vents on the infected case side of the bus contracted COVID-19, nor did the driver or passengers sitting close to the door. The authors concluded that closed environments using recirculated air increases the transmissibility of SARS-CoV-2.
- A study examining a large COVID-19 outbreak in a meat-processing plant in Germany came to a similar conclusion. The authors considered the social and working conditions of the affected cases, and concluded that transmission of SARS-CoV-2 occurred over a distance of at least 8m due to the confined working space, proximity of workers, low outside air infiltration rate, and high rate of recirculated unfiltered air.
In conclusion there is evidence that COVID-19 outbreaks are more commonly associated with indoor spaces, and that poor ventilation may increase the risk of transmission in such settings by facilitating the spread of droplets over longer distances.
Reference ‘Guidance on Non-Healthcare Building Ventilation during COVID-19’ V1.2 15.10.2020 for recommendations, however, HPSC, have advised proprietors to speak to their building engineer or system manufacturer before implementing any of the suggestions relating to mechanical ventilation. While we note that HPSC have provided specific guidance for schools and the use of Air Quality Monitors, the Department of Education and Skills (DoES) issued a document on the ‘Practical Steps for the Deployment of Good Ventilation Practices in Schools’ V2 30.11.2020.
The above reinforces the necessity for all governments to indicate to businesses, educational and medical facilities to get an independent true Ventilation Assessment of the current state of their ventilation system and advise on how the ventilation system, including air conditioning, can and should be configured using a Ventilation Strategy to reduce the risk of aerosol transmission.
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