Designing and Investigating Content Validity and Reliability of a Questionnaire for Preliminary Assessment of Heat Stress at Workplace

Heat stress is one of the most important consequences of occupational heat exposure worldwide. Current heat stress indices are not suitable for heat strain screening in developing countries, due to their inherent and applied limitations. This study aimed to design and investigate content validity and reliability of a pen-paper method for preliminary assessment of heat stress at work.

This cross-sectional study was conducted during 2009-2010. This research included three stages: (i) item generation based on literature review and interview; (ii) evaluation of content validity by 9 occupational health specialists and 30 occupational health providers; and (iii) reliability analysis performed on 98 workers.

Forty items were identified during item generation stage. In content validity evaluation stage occupational health specialists modified 27 items, removed 3 items and added 3 other items. In addition, occupational health providers modified 19 items. In reliability analysis, 15 items with item-total correlations less than 0.2 were omitted. Internal consistency (Cronbach's α) of the 25 remained items was 0.90.

The 25 measurable variables in our questionnaire were highly consistent with Wet Bulb Globe Temperature (WBGT) heat strain index and other questionnaires. Moreover, this questionnaire demonstrated high reliability. Therefore, after assessment of the structure and criteria validity, the questionnaire can be used for preliminary evaluation of heat stress in Iran.