One person is still missing and presumed dead following the July 27th explosion, which also injured 31 people.
The cause of the blast at the chemical park’s waste incineration site in the western city of Leverkusen remains unknown.
Prosecutors in nearby Cologne have opened an investigation against unknown persons on suspicion of involuntary manslaughter and causing an explosion through negligence.
The blast, which was heard several kilometres away and rattled the windows of nearby homes, sent up a cloud of black smoke.
It also triggered a fire in storage tanks for solvents that took firefighters hours to put out.
Residents were told to stay indoors and shut their windows for most of the day over concerns dangerous gases may have been released.
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Health officials said on Friday that initial investigations suggested there was no danger to residents’ health from the fallout.
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Early tests on soot particles showed “no critical levels of dioxin” or other toxic substances, Ulrich Quass of the enviroment department in North Rhine Westphalia state said.
Further analysis is ongoing and locals are still being advised not to eat fruit or vegetables from their gardens.
All those affected worked at the chemical park.
The blast area, in Leverkusen’s Buerrig district, is a short distance from Chempark’s main industrial park that houses numerous companies including Bayer, Lanxess and Evonik Industries.