fatemeh khaldari msc student, department of biostatistics and epidemiology, faculty of health, kerman university of medical sciences, kerman, iran; narges khanjani associate professor, environmental health engineering research center, kerman university of medical sciences, kerman, iran abbas bahrampour professor, department of biostatistics and epidemiology, faculty of health, kerman university of medical sciences, kerman, iran mohammad reza ghotbi ravandi assistant professor, department of occupational health, faculty of health, kerman university of medical sciences, kerman, iran ali ali asghar arabi mianroodi assistant professor, department of ear, nose and throat, faculty of medicine, kerman university of medical sciences, kerman, iran