An open letter to Dr. Tedros Adhanom Ghebreyesus, the new-in-post Director-General of the World Health Organization, implores WHO to update its critical guidance on ventilation.
The letter, written by the managing director of air purification company RENSAIR, says that after finally accepting that COVID-19 is mainly spread via airborne particles rather than contaminated surfaces, the WHO’s April 2021 ‘Roadmap to improve and ensure good indoor ventilation in the context of COVID-19’ rightly shifted its emphasis to infection control measures relating to clean air.
However, Mr Ballsdon remains concerned that Covid-19 and its variants “continue to pose a serious threat to world health and there are a number of issues in the roadmap that demand urgent attention.”
The letter makes a series of points regarding the recommended air change rate of 10 Litres fresh air/second/person (L/s/person) in non-residential settings. “This is a positive step forward, but the reality is there is a huge gulf between the ideal and the real. Many buildings’ Air Handling Units provide ventilation rates nowhere close to 10 L/s/person and a substantial number of older buildings offer no ventilation at all. Similarly, many hospitals are structurally under-ventilated and cannot attain the higher 60 L/s/patient air change rate stipulated for health care settings,” he says.
Mr Ballsdon goes on to write that “on a global level, this shortfall needs to be acknowledged as the norm, rather than an exception to the rule. Where there is a need to plug the gap, portable air purifiers should not be seen as a last resort [“if no other (short-term) strategy can be adopted’]”.
The letter also calls for stricter guidance on UVC light:
“The guidance should mandate that the ultraviolet lamp is enclosed, so as not to harm the eyes, and that the wavelength must be above 240 nanometers to ensure efficacy without producing any ozone.”
Energy impacts
The often overlooked issue of the energy impacts of increased ventilation rates to meet WHO guidelines is also addressed.
Mr Ballsdon says there is a “sizeable energy cost saving in using air purification instead of increasing the AHU ventilation rate”. For rooms without AHUs, using an air purifier allows for windows to remain closed for longer, reducing the energy used by radiators. “This is of particular benefit in large older buildings, such as schools. And of course, lower energy consumption means a significantly lower carbon footprint, an air purification advantage that supports the UN’s goal to dramatically cut worldwide emissions and limit global warming to a maximum of 2 degrees this century. This hugely important aspect should not be overlooked in the ventilation roadmap.”
‘Sent in good faith’
Commenting on his letter to the WHO, RENSAIR’s MD says: “The suggestions made in this letter are intended to be constructive, made in good faith, with a view to building on the positive steps that the WHO has taken to date in relation to mitigating the threat of COVID-19.”
To read the letter in full – follow this link.
Content Team
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