Air Conditioning and Ventilation Systems

Our Ref: HSR/1/3
Head Office Circular: NP/134/20
2nd June 2020
To: The Secretary

Dear Colleague,


I have received a response from the Office of Rail and Road (ORR) to some important matters I raised around air conditioning and ventilation systems on trains. The full response, together with links to appropriate standards, guidance and advice is attached to this circular.

I asked about common industry standards for rail vehicle ventilation systems; not all rail vehicles will have modern heating, ventilation and air conditioning systems (HVAC) to the latest design standard.

Train operators are required to carry out a risk assessment to assess the hazards applicable to the use of the vehicle in the particular circumstances for which it is intended. The latest advice from HSE is that is that the risk of HVAC systems spreading coronavirus is very low but, where centralised ventilation systems remove and circulate air to different rooms or enclosed spaces, it is recommended that the recirculation mode should be switched off and a fresh air supply used.

There is emerging research on the potential for HVAC systems to affect the transmission of the virus within buildings, but not specifically within trains. The current evidence supports the general principles of reducing recirculating air and increasing fresh air flow within indoor spaces in order to minimise risk of coronavirus transmission. For cleaning and maintenance operations on HVAC systems, the HVAC industry guidance suggests that appropriate personal protective equipment should be worn and all materials, including old filters, carefully bagged and disposed of safely.

Consideration should be given to the reasonable practicability of adjustment to recirculating air conditioning systems to increase fresh air flow, and to the use of enhanced filtration; and opening of windows where possible and safe to do. Any proposed adjustments to vehicle ventilation systems will need to be risk assessed; risks to staff maintaining HVAC systems should also be risk assessed.

The ORR have informed me that they will continue to use best available evidence and guidance from HSE and other expert bodies to inform advice to trade union representatives on this issue.

Please make the contents of this Circular available to all appropriate members.

Yours sincerely

Mick Cash
General Secretary