We probably all braced ourselves for a Covid spike and the “flu-demic” when the schools went back, and the offices eventually opened after holidays and rail strikes. After all ‘Living with Covid’ is the new mantra.
What does that mean in practice? The high-level government emphasis remains on letting fresh air in, general cleanliness and personal hygiene, but drill down and there is more specific guidance to consider, and it’s underpinned by the might of overarching Health and Safety Law.
The Health and Safety Executive guidance on how to assess and improve ventilation is in line with regulations that existed long before Covid. So you should already be providing a safe workspace. Do not assume that you need to invest heavily in new plant, as long as what you have is properly installed and maintained.
There is, as there has been for decades, a legal duty to provide sufficient fresh air, and that starts with identifying work areas that are poorly ventilated, usually because there is no scope to open windows, doors or vents for natural ventilation. Desk or ceiling fans are no answer- they just move the stuffy air around.
What is good ventilation?
The ventilation rate refers to the volume of air that is provided to a room over a period of time. What is necessary for adequate general ventilation will depend on several factors such as the amount of floor space per occupant, and the work activity.
HSE’s Approved Code of Practice and guidance tells us that ‘The fresh-air supply rate should not normally fall below 5 to 8 litres per second, per occupant’ – which is pretty meaningless to the lay-person. A useful way to estimate oxygen levels is to use carbon dioxide monitors. However they don’t fix the problem: they just flag it up (hopefully before a classroom full of school children or your office team get drowsy andstart to lose focus).
The principle of good ventilation is not rocket science: you just need to ensure that stale air is replaced. To mitigate COVID and other respiratory virus transmission the goal is to dilute or extract from the air virus-laden aerosols faster than they are produced. In many cases, the HSE guidance says, windows or other openings will do the job. Elsewhere, mechanical ventilation systems are needed.
Given that we are operating under long-standing legislation and guidance, then existing mechnaical ventialton systems, if set up properly and well-maintained and cleaned, should suffice.
Is my system good enough?
Do you know how effective your mechanical ventilation systems are at changing old, potentially-contaminated air for new?
If they are working properly, and you have complied with existing guidance and standards, then they are probably fine. However, do take time to review the way your systems are set up and working, carry out essential inspection and cleaning works and ensure your compliance records are up to date. The starting point is a professional risk assessment and system audit – you should always have up to date versions of both.
Ensure that you are operating HVAC plant to obtain the right target air change rates and that the system is properly balanced (or rebalanced after cleaning or maintenance work) to achieve uniform air distribution and reduce dead spots.
Be sure to keep the system clean. Soiled ducting and air grilles in ventilation systems can contaminate the air or reduce air circulation, possibly below critical air change rates.
What’s involved in maintaining safe ventilation hygiene and air quality? Check out our specialist air services.
13 01 2023
