The accident took place on Saturday in the Jiemeifengyou Chemical Plant in Ningdong Energy and Chemical production base located in Yichuan provincial capital of northwest China's Ningxia Hui Autonomous Region, state-run Xinhua news agency reported.
Most of the victims showed minor poisoning symptoms. Four people who were seriously poisoned are out of danger after overnight emergency medical treatment.
Witnesses say ammonia gas and highly concentrated ammonia liquids spurted out from a flare piping in the southeast corner of the plant.
The company kept spraying water in the polluted areas to dilute the gas in the air.
Currently, the air quality around the periphery of the plant has met the safety standards, the report said.
Once inhaled by human beings, ammonia damages the oxygen carrying capacity of blood cells and causes soar throat, tear-shedding, coughs, chest distress, difficult breathing and even the life-threatening cardiac arrest.
The cause of the accident is under investigated.
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