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COVID-19 update: A bug’s life

Published 19th March, 2020 by Neil Nixon

COVID-19 update: A bug’s life

Coronavirus has been at the top of the news agenda over the last few weeks for all the wrong reasons, but there are ways to mitigate its impact. Air filtration, for example, has a critical role to play in removing harmful pathogens from the air. Neil Nixon speaks to Mark Taylor from Camfil to learn more.

Every single headline on the webpage of a major national newspaper’s recent ‘most read’ section contained the word ‘coronavirus’. Clearly, the latest strain of the virus - known as Covid-19 - is preying on the minds of many people in the UK and around the world.

Covid-19 is by no means the only pathogen to threaten people’s health, however. More than 800 million viruses fall on every square metre of the planetary boundary layer (the lowest part of the atmosphere) every day - the equivalent of 12 viruses for every person in the UK.

That makes the risk of catching an infection via virus high and, unlike bacteria, rain can’t wash them away. However, Covid-19 is particularly troubling because it is a new strain of coronavirus that has not previously been identified in humans.

The European Centre for Disease Prevention and Control says: ‘Outbreaks of novel virus infections among people are always of public health concern, especially when there’s little knowledge about the characteristics of the virus, how it spreads between people, how severe are the resulting infections, and how to treat them.’

Indeed, the new coronavirus presents particular challenges. For example, there is no specific medicine recommended to prevent or treat Covid-19 and there are currently no vaccines against it.

This begs a fundamental question - what can people do to protect themselves? There are, of course, a variety of hygiene measures they can take to reduce the likelihood of catching an infection. These include, most importantly, thoroughly washing hands often with soap.

Other mitigation measures recommended by the professionals include not touching the eyes, nose and mouth; covering the mouth and nose with a tissue (and discard) or flexed elbow when coughing or sneezing; using a fist or knuckle to operate light switches etc; and avoiding unnecessary contact with others.

But what about physical methods? Face masks have been discussed as a possible anti-virus protection measure although there is considerable debate among health professionals about how effective they are against Covid-19. Experts warn that, even if they can be effective, to offer real protection against infection face masks must be of the right type to filter out infectious air particles.

The same rule applies to filters used for virus control in healthcare facilities. Indeed, many professional engineering organisations recommend HEPA (high-efficiency particulate air) filters in hospitals, infection control clinics and other buildings dedicated to healthcare to eliminate microbes and other dangerous particles. HEPA filters have been proven over decades across a wide range of health-related and life sciences applications, controlling the spread of airborne particles and organisms including viruses and bacteria. True HEPA filters are tested to EN 1822 and ISO 29463 standards and their efficiency is measured in terms of MPPS (most penetrating particle size). The MPPS associated with HEPA filters is typically between 0.1 and 0.25 micrometre. Bacteria and viruses are often smaller than that, but typically attach themselves to larger particles.

HEPA filters don’t actively kill living organisms. Rather, they capture and hold them within the matrix of the filter. This means that they can be installed in HVAC systems, filtering out biological pollutants and particulate matter carried by the airstream, preventing them from entering or recirculating back into the room.

The air filtration selected depends on the category of the risk when in application. High-density areas with most affected surroundings such as laboratories, containment units and quarantined zones need higher level of protection than low risk exposure surroundings or controlled areas like homes or small business space.

High risk applications need specialist ventilation systems and filtration equipment usually of HEPA Class H13 (with an overall efficiency of 99.95%) or higher along with use of special personnel equipment and clothing.

Viruses will always pose a threat to human life, with new and incurable strains a symptom of the modern world. In our healthcare establishments at least patients and staff should feel safe; correctly designed ventilation systems with the right level of air filtration are a key line of defence in this battle.

In order to educate about role of air filtration and containment of airborne infections to reduce the risk indoors, Camfil has created a series of infographics that provides value-based insights in order to combat airborne viruses (

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