Fifteen people were hospitalised on Friday after inhaling ammonia gas at a factory in Olifantsfontein near Midrand, according to Netwerk24.
If ammonia gas is inhaled deeply, it can lead to death, according to Health24.
Earlier News24 reported that 50 people had been injured in a chemical gas explosion at a business on Industry Street.
"Assessments showed that approximately 50 people had sustained minor to moderate injuries. Fortunately, no serious injuries or fatalities were found on the scene," ER24 spokesperson Russell Meiring said in a statement on Friday.
Frans van Heerden, operating head of Festive, where the incident happened, told Netwerk24 that there had been no explosion.
He said that at about 06:30 an ammonia leak was discovered emanating from one of the pieces of cooling equipment on the premises.
He said the premises were quickly evacuated.
After the leak was found, "the area was declared safe by the Ekurhuleni emergency services", Van Heerden told Netwerk24.
Investigations were underway into what led to the leak.
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