Victims of a blast at a Pegatron plant that injured 61 workers have spoken about their experiences.
Among the claims made by the victims is that Apple had inspected the Shanghai plant hours before the explosion. One worker explained that he had been calibrating the machine he operated, which polished iPad 2 casings, when the blast occurred.
"I saw a fireball coming towards me. I lost consciousness for a few seconds. Later, when I opened my eyes, I saw dense smoke and fire everywhere. I felt scared, really scared. I could hear people crying and screaming," said 24-year-old He Wenwen.
He criticised the system used to vaccuum up the dust created by the polishing machines as ineffective, saying that when workers removed the thick masks they wore that their "nostrils were full of dust" and that the air in the plant was like "fog".
Workers - who earn between $200 and $450 per month (£125 - £185) - were told to clean up the dust on the day of the explosion as Apple inspectors were due to visit, the report claims. Workers were told not to speak to the inspectors.
According to Pegatron, 24 of the workers injured in the blast suffered burns and NPR's report shows images of victims taken at a hospital where they are being treated for their injuries.
Conditions in plants operated by Apple's suppliers have been under scrutiny since a series of articles in the New York Times cast doubts over safety standards and working conditions.
Apple was quick to react, inviting the Fair Labor Association (FLA) to inspect plants belonging to its key suppliers.
The explosion at the Shanghai Pegatron plant wasn't the only blast at an Apple supplier's facility in 2011 - in May, four workers were killed in an explosion at Foxconn's Chengdu plant. Later in the year, fire broke out at another Foxconn plant in Yantai.
Conditions in Foxconn plants had already been under scrutiny after a spate of suicides among workers. Earlier this year, a group of workers had threatened to jump off a building at Foxconn's Wuhan plant in a dispute over wages.
The NPR report claims that the workers interviewed for the article had not been contacted by Apple since the explosion, though after NPR contacted Apple, some had received calls from the company checking on their injuries and that they had received compensation.