BURNABY (NEWS1130) – When did composting become so unsafe? That’s the question that’s being raised during the final days of the coroners’ inquest into the deaths and serious injuries of Langley mushroom farm workers in 2008.

Dr. Anthony Lau is a professor of Chemical and Biological Engineering at UBC and an expert in composting.

He talked about the bio gas emissions those workers would have encountered, especially dealing with poor ventilation. He couldn’t say for certain which, if any, of the toxic gases killed or injured the five men, saying the lack of oxygen would have also contributed.

If he could make recommendations, they’d be to aerate the materials, actively treat the waste water, improve ventilation and filtration.

The jury has already heard from the mushroom farm’s co-owners. Majority owner Ha Truong said he did not know composting mushrooms created potentially-deadly gas.

Tomorrow, the inquest will hear from Jim Sinclair, President of the BC Federation of Labour, and family members before the jury deliberates.