Health Ministry officials ordered the closure and evacuation Thursday of all employees in some 40 companies located at BES Industrial Park and Free Zone, in the province of Alajuela, west of San José.
The closure measure was filed by the Environmental Court after an investigation determined there was a mysterious white foam on the waste-water treatment system in the free zone.
The analyses were made by the National Water and Sewer Institute (AyA), and indicated that the foam was being poured down the walls and deposited in the storm-water pipes.
The closing of the industrial park was requested by the Environmental Court two weeks ago, after environmental groups claimed that the industrial park companies were pouring foam into Siquiares River.