Heat stress assessment among workers in a Nicaraguan sugarcane farm

BACKGROUND Heat illness is a major cause of preventable morbidity worldwide. Workers exposed to intense heat can become unable to activate compensation mechanisms, putting their health at risk. Heat stress also has a direct impact on production by causing poor task performance and it increases the possibility of work-related morbidity and injuries. During the sugarcane harvest period, workers are exposed to excessive sunlight and heat from approximately 6 am to 3 pm. A first assessment of heat stress during the 2006/2007 harvesting season served to redesign the existing rehydration measures. In this project, sugarcane workers were provided with more rehydration solutions and water during their work schedule. OBJECTIVE To assess heat stress preventive measures in order to improve existing rehydration strategies as a means of increasing productivity. METHODS A small group of 22 workers were followed up for 15 days during working hours, from 6 am to 3 pm. Selection criteria were defined: to have worked more than 50% of the day's working schedule and to have worked for at least 10 days of the follow-up period. A simple data recollection sheet was used. Information regarding the amount of liquid intake was registered. Production output data was also registered. Temperature measurements were recorded by using a portable temperature monitoring device ('EasyLog', model EL-USB-2). RESULTS The average temperature measurements were above the Nicaraguan Ministry of Labour thresholds. Seven workers drank 7-8 L of liquid, improving their production. Output production increased significantly (p=0.005) among those best hydrated, from 5.5 to 8 tons of cut sugarcane per worker per day. CONCLUSIONS Productivity improved with the new rehydration measures. Awareness among workers concerning heat stress prevention was increased.