A pregnant woman injured by a high quantity of poisonous gas that was accidentally released at the aquatics centre at London’s Olympic park is planning to sue the company that runs the pool. Tess Riley, 37, who fled the pool with her husband, Thom, and their two-year-old daughter Ruby, said they “vomited our guts out” after the incident, which took place moments after a parent and toddler session in the centre’s training pool on Wednesday morning. As well as being left with the trauma of the “apocalyptic scenes”, Riley has been left fraught with anxiety over any potential impact the chlorine gas has had on her 15-week pregnancy. “I am an angry woman who is planning to sue,” she said. Riley, a former Guardian journalist, was among 29 people taken to hospital, where she was treated with oxygen in an isolation room while her clothes were placed in a contamination bag. She was observed by a team of trainee military doctors studying the effects of chemical attacks. Riley was the last to be discharged from the Royal London late on Wednesday evening. “The doctors said I had been the worst impacted,” she said. But she is yet to discover what, if any, effect the gas has had on her unborn child. London fire brigade said a “high quantity of chlorine gas” was released in the incident. But Riley needs to know whether any other gas was released on the day and so far has failed to get answers from Better, the firm which runs the centre. She is now consulting solicitors about legal action against the company. Newham council confirmed on Friday that its environmental health officers are undertaking an investigation into the accident. Riley, who like her daughter is still coughing from the incident, said: “I’m really, really concerned about the impact on my pregnancy. It has been very traumatic, I’m not sleeping.” She added: “My maternity team is waiting to hear from me about the gases that I was exposed to so that they can work out what treatment I need. The obstetrician who came to see me said ‘we don’t know how much you’ve been exposed to. We don’t know what’s built up in the placenta, and therefore we just can’t know’. So I need that information, but I don’t have it.” Two days after the incident, Riley is furious with Better for failing to contact her. “Despite putting out a lot of press guff about how they are supporting families, nobody at Better has contacted us,” she said. “I want to know what happened, how it happened, what I was exposed to, what the potential long-term health risks are and what they are doing to ensure another fuck-up like this never happens again.” She added: “I’m just amazed that the company has done absolutely bugger all and we are left in the dark about the whole thing. I want answers.” Some of those caught up in the incident reported minor breathing difficulties, but Riley said “we just couldn’t breathe” as the family were changing after their swim. She said: “We ran as fast as we could out the building. The staff on the desk looked baffled by this wall of people with toddlers in their arms running towards them coughing and retching. It was just an apocalyptic scene. There were school kids lined up outside the building who ended up needing medical help because this stuff was pouring out the building through the vents.” Riley said she saw at least two people pass out. “One woman was found slumped over her steering wheel,” she said. “I think she’d gone to her car feeling woozy.” It is understood one of the patients was struggling so much to breathe that they required intubation. Riley was taken to the Royal London after she found hyperventilating outside the centre. Other patients were taken to Newham and Homerton hospitals. Her daughter, who was coughing and screaming for two hours after the incident, was taken to the hospital’s paediatrics department where she was later discharged. Newham council said its environmental health officers are undertaking an investigation into leak. Sources close to the investigation said large quantities of chlorine were release when a delivery of hydrochloric acid was mistaken pumped into a tank containing bleach. Riley said: “If that’s what happened, why weren’t the pipes designed in such a way to prevent that? And why did it happen when the pool was being used?” Some of those caught up in the incident fled in their swimming costumes and goggles. Riley and her family were only half-dressed when it happened. The rest of her clothes as well has her keys, phone, glasses and her daughter’s pushchair remain in the aquatic centre. In a statement, GLL – which trades under the name Better – said: “Work at the London Aquatics Centre following Wednesday’s incident is ongoing and means the centre has remained closed. “We are in the process of contacting customers as it becomes possible to retrieve their personal belongings. “We understand the concern of customers but are unable to comment on specific details of the incident until the investigation is complete and we are made aware of the full details. However, the substance released was identified as chlorine gas by the London fire brigade. “Customers are advised to seek medical attention if their condition is of concern.”