A pizza left cooking for too long sparked a 999 fire alert.
Two firefighting crews from Hemel Hempstead rushed to the ground floor flat in St Albans Road just before 6.30am on Sunday.
It is believed the man inside had fallen asleep and firefighters had to kick the door in to gain access.
They had been alerted by sleeping neighbours who woke to the smell of smoke.
Firefighters ventilated the property before leaving.