A questionnaire-based pre-employment interview was administered to each worker to gather baseline data regarding demographics, general health, smoking history, respiratory
symptoms, occupational history, and expected job duties/department assignment. Follow-up interviewer-administered questionnaires contained additional questions regarding skin exposure, use of personal protective equipment (PPE) and temporal relationships of respiratory symptoms to work. Asthma-like symptoms included at least one of the following: cough, wheeze, chest tightness, and shortness of breath, and were classified as work-related if they worsened while at work and improved while away from work. Possible TDI skin exposure was determined from the questionnaire by assessing whether workers reported frequently touching or handling recently cured (within minutes of production) polyurethane foams