Dichlorofluoromethane (HCFC-21)

Produced for refrigeration, foam blowing, and as a chemical intermediate; released from manufacturing, equipment leaks, and improper disposal [1][2].

Mostly by breathing vapors at work or near leaking refrigeration lines; skin contact can occur with the cold liquid [3]. Exposure is higher in small, poorly ventilated spaces [4].

Short-term exposure can cause dizziness, headache, cough, and abnormal heart rhythms; very high levels can displace oxygen and cause unconsciousness. Liquid can cause frostbite. HCFC-21 also depletes ozone and has climate impacts [1][3].

HVAC/refrigeration technicians, foam/chemical manufacturing workers, and anyone near leaks in enclosed spaces; people with heart disease or those using stimulants may be more sensitive to rhythm effects [3][4].

Fix leaks promptly with EPA-certified technicians; never vent refrigerants; improve ventilation; upgrade to safer alternatives; follow workplace controls and PPE requirements [1][4].