Officers from the Pinner South Safer Neighbourhood have issued a message to residents after they found several discarded gas canisters.
The team found 14 of the canisters in Pinner Memorial Park at the start of this month and encouraged residents to come forward if they knew anyone supplying them.
Inhaling the gas from the canisters has been seen widely in recent years, often being inhaled using balloons.
Users believe that inhaling the gas will give an immediate ‘high’ but in fact, it can prove fatal.
A spokesperson for the team said: “Fourteen of these canisters were found discarded in Pinner Memorial Park.
“Gas inside them is released into balloons and inhaled.
“Instead of feeling euphoria, some inhalers die!
“We want a safer summer for everyone, so if you know who is using or selling this gas, contact us.”