Two men are recovering from carbon monoxide poisoning after an incident in Slinfold on Sunday morning (April 7).
Firefighters attended a home in Guildford Road at around 9.15am after the victims had suffered poisoning from a patio heater.
They were rushed to hospital.
A spokesperson for West Sussex Fire and Rescue Service said: “Carbon monoxide (CO) is the silent killer so make sure you are not at risk.
“Air is vital - heating appliances, whatever fuel they burn, need to be able to breathe in order to function efficiently. To breathe they need a constant and sufficient flow of air
“Heating and cooking appliances fuelled by coal, smokeless fuels, wood, oil and gas can all cause carbon monoxide poisoning if they are poorly installed, incorrectly used or not regularly maintained. Poisonous carbon monoxide gas is produced when fuel does not burn properly.”