Covid Ventilation Advice is all Wrong

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John Wilton-Davies

Since it became understood that airborne droplets, or aerosols, are a major risk factor in the spread of Covid-19, government advice has, albeit slowly, shifted away from an emphasis on surface cleaning to recognising the importance of ventilation. By introducing a constant stream of uncontaminated air to an indoor space, any airborne virus is diluted, significantly reducing the risk that occupants might become infected. Hence it is deemed safe to meet others outdoors and why school children throughout the country shiver in classrooms with windows wide open through all weathers.

Yet, whilst the rationale is sound, official guidance on implementation is profoundly flawed due to two fundamental failings: the lack of any cogent comparison between the dangers of Covid versus other consequential risks; and a complete lack of understanding over the capabilities of modern air purifiers.

Government ventilation advice immediately takes a wrong turn by introducing the term ‘fresh air’, with all its connotations, and presuming that this is the same as ‘air from outdoors’. This oddly supposes that all the known dangers of outdoor air pollution have magically disappeared in the face of the pandemic and ignores the rather important fact that air pollution kills more people in a year than have so far succumbed to the Covid-19. In most parts of the UK, air pollution is certainly a substantially greater risk to younger people than Covid.

As well as letting in air pollution, following the ventilation guidance also lets out all the heated (or, in warmer months, the cooled) air from a building. Heating costs will have risen exponentially, especially in schools where the guidance is followed most diligently, and created a total disconnect with our need and obligation to reduce our carbon footprint. As any student will now tell you, heating systems cannot keep up with open windows, so we’re burning fuel and having cold rooms. And cold workplaces lead to a big reduction in productivity, dwarfing even the increased heating bills in terms of lost income to businesses, reduced learning and lower grades in schools, and much more general ill-health for everyone.

In the real world comfort often trumps everything. A teacher can make a student keep a window open, but in an office, whatever the ventilation policy, a worker will close a window if it’s cold as soon as a manager’s back is turned. In recent news coverage of Covid deaths in care homes it was rare to see a single window open, despite the possible consequence of ignoring the advice.

Yet there’s a much better alternative. Modern, quality air purifiers reduce any airborne virus content just as effectively as an open window. Warm air is kept inside, so doesn’t need replacing, and productivity, health, income and comfort all improve significantly, Any outside pollution either doesn’t get in, or is quickly filtered out. Purifiers remove small airborne particulates, of which the virus is merely one example, as well as polluting gases, and the cost of installing suitable purifiers can be recovered in as little as a few weeks. So why aren’t we encouraged to use them?

This omission seems to arise from a lack of understanding of the capabilities of good quality purifiers. It’s certainly true that, in a substantially unregulated market, there are many products that are almost useless, and some manufacturers do make unfounded performance claims. This has led to a general scepticism over the efficacy of even the more effective options and influenced government and other science-based bodies in the detail of the guidance.

For those seeking expert guidance, the government refers readers to the Chartered Institute of Building Services Engineers (CIBSE)­ (1), where we are told (4.2.10), for example, that “air not remove...gaseous pollutants”. Tell that to a soldier relying on a gas mask for protection. A gas mask is merely one example of a portable air purifier, and the technology used by gas-removing purifiers is exactly the same as that employed in military gas masks.

Whilst the CIBSE does at least acknowledge that a HEPA particle purifier will remove airborne virus, it exhibits a complete lack of understanding of the purifier market, stating that ‘air cleaners’ can typically only clean an area up to 10m2’. In fact there is no limit to the area a purifier can deal with effectively, which is determined mainly by the power of the machine. Stand-alone portable purifiers, with a footprint of about 1ft2, can happily manage an area of up to 60m2 -about the size of an average classroom or large office.

Government advice, through the Health & Safety Executive (2), confuses the issue further. Whilst agreeing that air purifiers do remove airborne virus, it states that ‘these should not replace ventilation’. Of course, whilst removing excess CO2 is vital, ventilation, in terms of introducing ‘fresh’ air, is, as we’ve seen above, a flawed concept.

At Plain Air we believe that this combination of a lack of understanding of the true capabilities of quality air purifiers, together with a possible nervousness over false claims by some unscrupulous manufacturers and retailers, has resulted in official advice almost completely ignoring or dismissing the enormous value that properly specified purifiers can bring.

Managing Covid risks, minimising air pollution, reducing costs and maximising health and productivity does require a balance between ventilation and purification that depends on factors such as ambient air quality, level of Covid in the population, temperature and occupancy density, but we can help with that.

There really is a healthier, more effective and cheaper solution than opening the window.


Links: (1) CIBSE Ventilation Guidance


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