The deaths of a father, mother and their daughter inside a car parked beneath the ring road on Cairo’s Nile Corniche late last August have renewed warnings about leaving the engine and air conditioning running in an enclosed vehicle. Initial investigations linked the deaths to suffocation caused by a refrigerant leak, while other preliminary information pointed to the possible buildup of toxic gases, foremost among them carbon monoxide.
Carbon monoxide can build up around a car
Carbon monoxide is the most common hazard in such incidents. The colorless, odorless and tasteless gas is produced by the incomplete combustion of fuel inside the engine, and may collect beneath the car while it is stationary and the engine remains running.
The gas can enter the cabin through a hole in the exhaust system or damage to the floor insulation and door seals. When the air conditioning is set to draw air from outside, accumulated gases may be carried inside, while closed windows and prolonged use of air recirculation limit the renewal of air inside the vehicle.
Poisoning symptoms intensify within an hour
Refrigerant gases, commercially known as Freon, are less commonly involved in poisoning incidents, but can become dangerous when large quantities leak into an enclosed space. These gases can displace oxygen in the cabin and may also affect the nervous system and heart when exposure levels are high.
Signs of a refrigerant leak include a sudden drop in air-conditioning efficiency, warm air coming from the vents, hissing or whistling sounds, and the compressor switching on and off at short, frequent intervals. Oily spots may also appear on connections or hoses near the compressor. The risks increase when sleeping in a parked car with the engine running, particularly in enclosed garages and poorly ventilated areas.
Exhaust and air-conditioning faults increase gas exposure among passengers
Holes in exhaust pipes or the muffler, damaged door seals and vehicle flooring, and corrosion of the air-conditioning evaporator behind the dashboard can also allow gases to reach passengers. Safety guidelines advise against sleeping in a parked vehicle while the engine is running, whether it is in an open or enclosed location.
If it is necessary to keep the engine running briefly in an open area, a gap of two to three centimeters should be left in two opposite windows to renew the air. Partially opening the windows does not provide sufficient protection inside an enclosed garage or poorly ventilated site; the safe action is to switch off the engine and leave for an open area.
Prevention also includes regular inspection of the exhaust and air-conditioning systems, checking for holes or leaks, replacing the cabin filter, and checking refrigerant pressure according to the recommended maintenance schedules.
