More than 100 maternity staff members are taking legal action against an NHS hospital trust in England after allegedly being exposed to dangerous levels of nitrous oxide while working in a maternity unit.
The claimants, including midwives and healthcare assistants, worked at Basildon Hospital in Essex between 2018 and 2023. They say prolonged exposure to the gas caused a range of health problems, including chronic fatigue, headaches, anxiety, memory issues and “brain fog”.
The legal action has been filed against Mid and South Essex NHS Foundation Trust, which runs the hospital.
According to NHS figures, a total of 141 claims have been received so far. The trust has already paid out around £89,000 in settlements linked to allegations of exposure to “excessive and foreseeably dangerous” levels of Entonox, commonly known as gas and air.
Entonox is a mixture of nitrous oxide and oxygen widely used as pain relief during childbirth.
Claimants argue that poor ventilation inside maternity wards allowed nitrous oxide to build up in the air, exposing staff to unsafe conditions. Gas can escape into the atmosphere when patients exhale, from leaking gas lines or during equipment use.
An internal hospital report reportedly found that some staff were exposed to nitrous oxide levels up to 30 times higher than the legal workplace safety limit.
One female staff member involved in the legal case told media that staff members felt they had been “poisoned” by prolonged exposure.
“A lot of people were suffering from chronic fatigue, constant headaches, low vitamin B12, heart palpitations and very foggy heads,” she said.
She added that staff were seeking accountability from hospital management, saying many healthcare workers had continued caring for patients despite suffering ongoing symptoms.
Another midwife involved in the case said she collapsed at work due to severe headaches, anxiety and low mood, while another claimant reported nerve pain in her hands and feet.
Court filings also mention symptoms including irritability and extreme exhaustion.
The workers are each seeking compensation for personal injury exceeding £1,500.
A report seen by media outlets revealed that staff were allegedly not informed for 16 months about test results showing that gas exposure levels had breached safety regulations.
In 2024, the trust acknowledged there had been “unacceptable delays” in responding to the issue.
Denise Townsend, acting chief nursing officer for the trust, said lessons had been learned following the incident.
“Since the incident we have improved our oversight of the monitoring of medical gases across the maternity unit at Basildon Hospital,” she said.
The hospital trust has since installed new ventilation and extraction equipment designed to remove nitrous oxide from the air.
Concerns over high nitrous oxide levels have also been reported at several other maternity units across England in recent years.