Blast at MU chemistry lab called accidental

COLUMBIA, Mo. (AP) -- Fire investigators in Columbia say last month's explosion in a University of Missouri chemistry lab was accidental.

Four people were injured in the blast June 28 on the third floor of the university's Schweitzer Hall.

Columbia Fire Department Battalion Chief Steve Sapp says the blast originated inside an anaerobic chamber into which hydrogen gas was allowed to seep. The chamber was used for research requiring an oxygen-free environment.

KXEO-AM reports that workers were washing the chamber with pure nitrogen, not realizing there was also hydrogen inside, when the blast occurred.

Sapp says there were several ignition sources inside the chamber, making it impossible to say which of them caused the explosion.

Schweitzer Hall reopened within a few days, but the lab will have to be rebuilt.

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Information from: KXEO-AM, http://info.kxeo.com