A fire service has said it will no longer "waste time" attending automatic alarms at businesses during opening hours.
Cleveland Fire Brigade said it attended almost 600 alarm calls between 08:00 and 17:00 in one year but only 12 were actual fires.
The brigade said the onus was on businesses to make sure their systems were working properly.
Crews will still always attend residential automatic alarms.
The change will start on 2 October and applies to commercial premises, schools, public buildings and leisure complexes in a "bid to reduce time-wasting call-outs", the brigade said.
During the day when these premises are staffed confirmation of a fire must be made through a 999 call.
Phil Lancaster from the brigade said automatic alarms can often be triggered by cooking fumes, cigarette smoke, dust or other minor causes.
He said: "Our new policy will mean crews are not detracted from real emergencies where lives could be at risk."
The brigade will still respond to "high risk" properties such as hospitals and chemical sites at all times.
Heritage sites such as Ormesby Hall, Preston Park Hall and Wynyard Hall are also exempt from the new policy due to their "special risk".