The Health & Safety Executive (HSE) has issued a warning about Legionnaires' disease in unused water supplies as people return to work.

This is clearly a potential danger for stone companies with water recycling systems and water walls. Air conditioning also has the potential to spread Legionnaires' disease.

The HSE says: "If your building was closed or has had reduced occupancy during the coronavirus lock-down, water system stagnation can occur due to lack of use, increasing the risks of Legionnaires’ disease."

It says you should review your risk assessment and manage the legionella risks when you:

• reinstate a water system or start using it again
• restart some types of air conditioning units

You can find out what Legionnaires’ disease is, where it comes from, how people get it and symptoms and treatment by reading the HSE guidance at What is Legionnaires' disease?

On the plus side, HSE says the risk of air conditioning units spreading coronavirus is extremely low.

If you use a centralised ventilation system that removes and circulates air to different rooms, HSE recommends you turn off the recirculation and use a fresh air supply.

Other types of air conditioning systems should not need modifying as far as caronavirus is concerned, but be midful of the risk of Legionnaires' disease.