100 maternity staff sue Basildon hospital over nitrous oxide exposure

More than 100 maternity staff are taking legal action against Mid and South Essex NHS Foundation Trust after claims they were exposed to hazardous nitrous oxide in Basildon Hospital’s maternity unit for years.

The claims cover staff who worked at the Essex hospital between 2018 and 2023, including midwives and healthcare assistants. Workers have reported fatigue, anxiety, headaches and brain fog, and one unnamed staff member involved in the action said she and colleagues had been “poisoned”.

Nitrous oxide, known in maternity care as gas and air or Entonox, is meant to be a routine pain-relief option in labour. The problem is that leaks or poor ventilation can allow the gas to build up in the air staff breathe, turning a standard part of maternity care into a workplace hazard.

An internal hospital report found staff were exposed to gas levels up to 30 times higher than the legal workplace exposure limit. Earlier reporting put that limit at 100 parts per million, and said Basildon Hospital bosses had known about high Entonox levels since the summer of 2021. That timeline is now central to the safety questions surrounding the trust’s response.

In February 2024, an independent review concluded there had been an “unacceptable delay” in the trust’s response to staff concerns and accused it of a “failure to act with candour”. The findings deepen scrutiny of whether warnings from the maternity unit were fully tracked, escalated and acted upon before the exposure claims spread across more than 100 workers.

The case also raises wider questions about oversight in maternity safety. NHS England issued guidance on 2 March 2023 after concern that some maternity units were seeing nitrous oxide levels exceed permitted limits. The Health and Safety Executive has separate maternity-specific guidance aimed at preventing harm from high levels of exposure, and says employers must assess risks to pregnant workers and new mothers and suspend them on full pay if hazards cannot be controlled.

The issue has already prompted changes elsewhere. The Princess Alexandra Hospital in Harlow temporarily suspended gas and air use after air quality tests raised concerns. That reaction underscores the pressure now facing hospital managers to show when they knew about the risk, what monitoring they used, and why staff say exposure was allowed to continue for so long in Basildon’s maternity unit.