Background Qualitative and quantitative measures of occupational heat and work load exposure assessments can be used separately or in combination to assess heat and work load exposure. Further they can inform parameters useful in quantifying exposure-response and exposure-effect relationships for workers’ health, wellbeing and productivity. Methodological considerations for characterising short and long term health impacts from heat and work load exposure are discussed using examples from the Worker Health and Efficiency (WE) Program implemented in El Salvador sugarcane cutters during 2014-2016.

Methods and Results Data were collected in a cohort of three groups of sugarcane cutters (totalling 275 individuals) during two harvest periods (November 2014 – April 2015 and November 2015 – March 2016). Qualitative measures included descriptive observations, a standardised interview and focus groups. These measures helped identify affected workers and existing coping/protection mechanisms (or lack thereof). They also provided important contextual information essential for appropriate data interpretation and ensuing data collection. Quantitative measures included local climatic measures (QuesTemp, WeatherHawk), heat and dehydration symptoms (questionnaires), biological measures (i.e., urine and blood samples, heart rate, body temperature, and body movement) and productivity data (via employer production records). These measures are being used to quantify heat/work exposure-response and exposure-effect relationships in sugarcane cutters. Provisional analysis indicates that sugarcane cutters in coastal regions spent 38% (202 hours) of their time working in Wet Bulb Globe Temperatures ≥ 30°C, when full effort should only be exerted for 15 minutes per hour (calculated from hourly climate data collected over 102 workshifts). In a subset of workers (n = 15), internal body temperature exceeded 38°C.

Conclusions Exposure to high heat and work loads are occupational hazards. Occupational heat and work load exposures are more comprehensively assessed when both qualitative and quantitative measures are used. High-quality qualitative observation and consultation is essential for occupational heat/work load assessment and intervention.