Monitoring and improving ventilation in the workplace to support Covid-19 safe-working conditions

Monitoring and improving ventilation in the workplace to support Covid-19 safe-working conditions

  • Date: Monday 23rd August 2021
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Through a combination of Summer heat and a return to the workplace for many, if not all, workers following the easing of Covid-19 restrictions, the topic of ventilation is likely to be a current topic amongst management, workers and their representatives.

Under Regulation 6 of the Workplace (Health, Safety and Welfare Regulations) 1992, employers already have a duty to ensure effective and suitable provision of fresh or purified air through ventilation. However, with the increased public awareness of Covid-19 safety measures and continued focus from the HSE on safe-working conditions, ventilation is an important matter for employers to focus on to ensure they are fulfilling their duties.

Why ventilation is important

Adequate ventilation helps to reduce the amount of virus particles in the air, and therefore supports the reduction in transmission. Be aware, ventilation is not enough on its own as it will have minimal impact on droplet or contact transmission, so frequent cleaning, keeping a safe distance and frequent handwashing still remain essential.

Identifying poorly ventilated areas

As with a lot of situations with health and safety, some of our best indicators can simply be our senses and gut reaction; they are our primal indicators for the presence of danger. Areas that are hot, stuffy or smelly have the potential to be poorly ventilated. In addition, rooms with no windows, low ceilings or are busy, cramped and overpopulated can indicate that ventilation could be insufficient.

As would be the case in identifying the presence of substances and exposure levels under Regulation 10 of the Control of Substances Hazardous to Health Regulations 2002, a more certain way of ascertaining the effectiveness of your ventilation is through sampling and monitoring. In relation to your Covid-19 controls, this can be achieved through using a non-dispersed infrared (NDIR) CO2 monitor to ascertain the levels in the given area from persons exhaling within the enclosed space.

How to use a CO2 monitor

Once the monitor has been calibrated following the manufacturer’s instructions, location of the monitor is the first consideration to ensure accurate and reliable readings that are consistent. The monitor should be wall-mounted, placed at around head height and kept away from doors, windows and sources of air supply. You should also ensure that they are placed at least 50cm away from people as exhalation can interfere with them.

Measurements can vary during the course of a day based on activity in the workspace, so you should look to take measurements at set times on a daily basis, such as morning, lunch and afternoon. Be aware of extreme readings (400 or >1500 ppm) as this could indicate that the monitor is in the wrong location. Make sure that you keep a log of readings as this will help analysis and decide if you have an issue with your ventilation.

How the measurements will help you take action

Readings on CO2 monitors are measured in parts per million (PPM) and the measurements should be used as a broad guide to help you take the best action. The following figures can support you in establishing the thresholds in your organisation:


Normal levels for outside – if measuring this indoors consider moving the monitor


Indicates good ventilation


Indicates that improvements are required (temporary or permanent)


Indicates bad ventilation

Remember, these are guideline thresholds for indicators and further monitoring, or investigation may be required. Temporary improvements can include opening doors and windows to increase the air flow or reducing the number of people in the workspace through adapting the workload or giving additional breaks.

Improving ventilation

Natural ventilation can be improved through increasing the number of open doors and windows, but do not prop open fire doors unless they can release and automatically close by being linked into the fire alarm system. You can ensure the workplace starts with better ventilation by opening doors and windows 30-60 minutes before work commences. Cooler and windier weather will naturally increase the amount of ventilation but do consider the impact of temperature and thermal comfort for the workforce – consultation with staff is essential to ensure the right balance can be met!

Mechanical ventilation brings fresh air in from outside and the first thing to ensure its efficiency is to be aware of how the system operates, it’s being operated within the manufacturer’s guidelines and that it draws in fresh air. Whilst room capacities can vary, it’s best to set and maintain the ventilation for the maximum occupancy of the space. Mechanical systems should maximise fresh air and minimise recirculation – you may need to increase natural ventilation to support this, such as heating and cooling units. You should avoid recirculating air between one space and another and be aware that recirculation units, including air conditioning, can mask poor ventilation as they only make an area feel more comfortable.

Further information and guidance

The HSE continue to review and publish updated guidance, resources and videos to support organisations in managing risks associated with ventilation in the workplace and maintaining relevant Covid-19 controls. More detailed guidance can be found by clicking here.

Don’t forget you can also contact SSG for a range of consultancy, training and Covid-19 services and resources!

Source: Dave Wright

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