Evaluation of Heat Stress Among Outdoor Construction Workers in Lagos Metropolis

Abstract

This study evaluated the extent of heat stress experienced by outdoor construction workers within Lagos Metropolis, Nigeria, using the Heat Stress Index (HSI) approach. It aimed to assess workers perceived thermal discomfort and determine whether significant differences in heat exposure existed across occupational roles. Data were collected from 174 respondents using structured questionnaires assessing eight heat-related variables, including thermal sensation, sweating, fatigue, dizziness, hydration, and rest patterns. The Heat Stress Index (HSI) was computed on a five-point scale and categorized into four levels: mild, moderate, high, and extreme. Results revealed that all respondents experienced some degree of heat stress, with the majority (62.1%) falling within the moderate category, followed by 22.4% reporting high and 2.9% extreme stress levels. Unskilled labourers recorded the highest stress values, reflecting greater vulnerability due to physically demanding tasks and prolonged exposure to direct sunlight. However, the one-way ANOVA test showed no statistically significant difference in HSI across occupational roles (F = 0.422; p = 0.737), indicating uniform exposure to heat stress conditions on-site. The study concludes that heat stress is a prevalent occupational hazard among construction workers in Lagos, driven by environmental rather than role-specific factors. It recommends implementing structured work–rest cycles, shaded rest zones, hydration schedules, and mandatory heat safety training to safeguard worker health and improve productivity under Lagos’s increasingly hot and humid climate.