A special gas sensor firefighters used after the death of a seven-year-old boy from suspected toxic fumes during severe flooding detected deadly hydrogen cyanide but no carbon monoxide, an inquest has heard.
Bruce Jolliffe, a scientific adviser to Surrey Fire and Rescue, said firefighters reported results of 30 parts per million of hydrogen cyanide after Zane Gbangbola was found dead in his bed at his home in Chertsey in February 2014.
Jolliffe told the coroner Richard Travers, the presence of the gas was not however confirmed in a back-up test. “It means the detection of hydrogen cyanide is, overall, unreliable.”
Questioned by Leslie Thomas QC – counsel for Zane’s parents, Kye Gbangbola and Nicole Lawler – Jolliffe said he was not aware that further readings of “exceptionally high” levels of hydrogen cyanide had been taken later the same day.
Thomas said a witness statement from one Environment Agency officer, sent to the scene to collect water samples, would say firefighters had told her that they had taken readings of 2,400ppm.
Jolliffe said: “I would question the extent of the reading. I mean, 2,400ppm is very large.”
Another reading, Thomas said, reportedly recorded 2,500ppm.
“If it was 2,500ppm, how high is that?” the coroner asked Jolliffe. “Exceptionally high,” he replied.
The inquest has heard that Zane’s family believe he may have inhaled hydrogen cyanide that seeped into their basement in floodwater from a nearby lake on a former landfill site. Zane’s father has been paralysed from the waist down since the incident.
A competing theory is that Zane died from carbon monoxide poisoning, the coroner said, possibly from a petrol-driven flood pump that his parents hired shortly before his death, but which they have insisted they never used.
Jolliffe said two other gases could also trigger the hydrogen cyanide alarm in the microtector and could have activated the alarm in this case – nitric oxide and nitrogen dioxide. In his report, he concluded that both gases and carbon monoxide would be present in exhaust fumes from a petrol pump.
Thomas asked him if any carbon monoxide had been detected at the scene: “Of all the sweeps there was not one reading of carbon monoxide, correct?”
Jolliffe agreed.
Thomas said that if the fumes were from the petrol pump, there should be seven or eight times more carbon monoxide than nitrogen oxides detected, “and not a scrap of it was detected”.
“Doesn’t that lead you to believe that wasn’t a false reading, but was hydrogen cyanide?” Thomas asked Jolliffe.
“No,” Jolliffe replied. The testing was conducted several hours after Zane’s death, and more buoyant gases such as carbon monoxide “would have left the house swiftly”, he said.
The inquest, which is expected to last six weeks, continues.
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