This article is a summary of our whitepaper of 8th June 2020 on HVAC pandemic considerations for food production sites with regard to indoor air quality (IAQ) both during and post the COVID-19 outbreak. The guidance is of relevance to anyone with responsibility for food safety and the health and safety of employees and has been collated from a variety of sources.
Uncertainties still remain about how the coronavirus is transmitted, however, experts are recommending certain HVAC engineering controls to help prevent airborne transmission. These recommendations should be used in conjunction with other measures, such as social distancing, PPE and hand hygiene etc.
Avoid Recirculating Air
Experts agree that ventilation systems that normally run with a recirculation mode should now be configured to run on full outside air where possible. According to the Chartered Institution of Building Services Engineers CIBSE), you should avoid recirculating air, ‘‘unless this is the only way of providing adequately high ventilation to all occupied rooms’.
Review Ventilation Strategy
CIBSE also states the importance of conducting a review of your ventilation strategy. According to the Building Engineering Services Association (BESA), you should take into account any measures you might have put in place in response to the pandemic, that might be restricting the air flow, e.g. partitions for social distancing of employees. The HVDS risk assessment template is available to help you conduct a comprehensive survey. Contact us for more details.
Increase Ventilation Operating Times
The Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA) recommends increasing the air supply and exhaust ventilation operation times of mechanical ventilation systems. As HVAC systems are tailored to the specific requirements of individual sites, the ventilation rate need to be considered in conjunction with relative humidity, temperature control, air flow direction and air flow distribution. For this reason, systems should be adjusted by HVAC engineers, as advised by a ScienceDirect paper, How can airborne transmission of COVID-19 indoors be minimised? published online by Elsevier Ltd. on 27th May 2020.
Implement a More Frequent and Rigorous Cleaning Regime
HVAC experts are predicting the increased significance of ventilation hygiene going forwards. According to the BESA, ‘It is more important than ever if systems are operating on full fresh air that ductwork is properly clean’. It is also important to note that a facility that has moved to a higher risk category because of changes as a result of the pandemic, will require more frequent ventilation cleaning. Cleaning should be carried out in accordance with the BRCGS Food Safety Issue 8.
Increase Frequency of Air Filter Changes
In addition to increased cleaning, the BESA also advocates more regular filter changes to stop microbial growth on filters. At HVDS, we recommend the more preventative course of action of changing filters to a set schedule rather than to pressure drop readings.
Consider using a Finer Grade of Filtration
For buildings that require a higher level of contamination control, HEPA filters are able to catch 99.97% of airborne particles 0.3 microns in diameter or larger. Not all air handling unit fans, however, are have the capacity to create the additional airflow necessary to push air through HEPA filters. However, secondary filters can be increased to F9/ISO 16890 ePM1 80%.
Check Rotary Heat Exchangers for Leakage
HVAC systems with heat exchangers may carry virus-laden particles via leaks from the exhaust air side to the supply air side, which can re-enter the building under certain conditions, according the REHVA. CIBSE recommends bypassing the thermal wheel – or where this isn’t possible, turning off the rotor and increasing the ventilation rates. Leakage is not an issue if an HVAC system is equipped with a device that guarantees 100% air separation between the return and the supply side.
Test and Maintain Local Exhaust Ventilation (LEV) Equipment as Normal
The HSE have stated that it is essential to continue to carry out regular inspection and testing of LEV equipment throughout the pandemic as normal. To comply with the law, a thorough examination and test (TExT) of LEV equipment must be undertaken every 14 months to protect employees from hazardous substances, such as dust, fume, mist, spray and oil in the workplace. In its ‘return to work guidance’, the British Occupational Hygiene Society (BOHS) stresses that the ‘HSE is not issuing exemptions or relaxation of these requirements’. According to the HSE, if your LEV system is restarting after a period of inactivity, it must be examined and tested prior to use.
For more information on HVAC pandemic considerations, see our whitepaper of 8th June 2020. The information contained both in this article and in the white paper may be subject to change as the situation with regard to HVAC and the pandemic is in constant review. As ever, we aim to bring you the latest thinking to help you keep your on-site indoor air clean. See also our Coronavirus Resource Hub to keep you safe and up-to-date. The hub includes all the latest food industry news, which is updated daily.