The US Food and Drug Administration (FDA) on Tuesday announced that it’s calling on consumers, businesses, schools and health providers to immediately stop using OxySure Therapeutics’ Portable Emergency Oxygen System, Model 615, after the company’s voluntary recall from last year was ineffective.

FDA said it has received multiple complaints and reports of adverse events associated with the device’s malfunctions, including insufficient oxygen flow, re-breathing of exhaled gases, burns, bruising (contusions) and exposure to chemicals.

The agency added that chemical reactions in the canisters could cause them to explode.

Since June 2013, OxySure has distributed at least 1,000 units of this portable emergency oxygen system nationwide. The devices may be purchased without a prescription and can be used in businesses, schools and other public places (e.g.., gyms, shopping malls, and airports).

FDA Inspections, Prior Recall

During a September 2014 inspection of one of OxySure’s facilities, FDA found that the company’s internal testing revealed the device’s oxygen flow rate to be too low and did not meet the FDA-cleared minimum specification of six liters per minute for a minimum of 15 minutes.

Three months later, FDA issued a warning letter to OxySure for not addressing these flow rate issues.

In June 2015, OxySure voluntarily recalled the replacement cartridges for Model 615, lots 61-65 because the oxygen flow rate did not meet the labeled specification. Later that month, the company instructed customers to review their inventory and dispose of the affected product.

FDA conducted a follow-up inspection of the manufacturing facility in September 2015 and found the device’s oxygen flow rate again failed to meet the minimum specifications.

In addition, an FDA recall audit check determined the June 2015 recall was ineffective because the recalled products were observed at user sites visited by FDA and available for use by customers.

FDA notified the company on 18 December 2015 of its deficiencies in recalling the product and calling on the company to identify corrective actions to ensure the defective product was not being used by consumers.

The company did not respond to a request for comment.

FDA Recommends Against Using OxySure Portable Emergency Oxygen System, Model 615: FDA Safety Communication