POISONOUS gases on the grounds ofthe industrial park Metro Free Zone inBarreal de Heredia, northwest of San José,prompted the evacuation of an estimated1,800 workers last week.Humidity seeping into a 15-kilogrambarrel of sodium hydrosulfite increased thetemperature of the chemical and resulted inthe gases at Hilos A y E de Costa Rica, athread manufacturer.Employees first noted the fumes atabout 6:30 a.m. on June 2. Firefightersand Ministry of Health workers useddiatomite, a chemical powder, to neutralizethe reaction and control the fumeswithin about three hours, estimatedRodrigo Elias, Hilos A y E operatingmanager.Alarms sounded in companies within a250-meter radius of Hilos A y E, sparkingthe evacuation of 1,800 employees,according to Ronald Orozco, the park’sdirector of Management and MarketingDevelopment.ELIAS reported that firefighters andMinistry of Health workers attempted todilute the chemical with water in order tolower the temperature inside the barrel.The barrel was left open to cool, butthe temperature increased again about1:30 p.m. and released more fumes.Firefighters finally neutralized the dangerby sufficiently diluting the chemicalwith water by 4 p.m.Evacuated workers waited outside forthree hours in the morning before employerssent them home. Six workers reportedrespiratory problems as a result of thefumes; they visited the park’s medical clinic,which later discharged them.Red Cross spokesman Alfredo Jiménezsupported the medical clinic’s decision,saying that the poison’s effects wouldn’tlast long.“They would have respiratory problemsat the time, but not anymore.”JIMÉNEZ characterized the incident asserious, but noted that a limited number ofpeople were exposed to the fumes.“This was important because it waschemical, but it didn’t affect a lot of people.”Hilos A y E’s Elias emphasized thefact that only fumes escaped from thecontainers.“It was not a chemical spill,” Elias insisted,adding, “It was an emergency that couldhappen in any industry.”Hilos A y E is a subsidiary of Americanand Efird, a North Carolina-based manufacturerof sewing thread. Hilos’s Elias statedthat his company conforms to American andEfird’s corporate regulations.No one could be reached for commentfrom American and Efird’s United Statesoffices.METRO Free Zone is an industrialpark with more than 55 companiesemploying about 6,500 workers, accordingto Metro Free Zone’s Orozco. Companiesin the park, which opened 15 years ago,receive government tax exemptions onimports and exports.The park has safety clauses for thecompanies within its borders.“Each company is responsible to thegovernmental organizations that offer safetyprocedures and measures for their operations.Moreover each firm has a contingencyplan under the park’s safety department,”Orozco explained.Jiménez explained that while the RedCross ensured that those affected by thevapors received treatment, the fire departmentdirected the site’s operations.“Firefighters decide who evacuates andwho doesn’t,” Jiménez said.ACCORDING to the fire department’sorders, “the internal roads and borderaccess roads were watched and cordonedoff by members of the park’s securityto avoid unauthorized people comingnear the site,” explained Orozco.Those not allowed in included membersof the press, on the grounds that theresponse teams needed to work withoutinterference.