Calculation of critical time of development of occupational diseases is a necessary and effective method of prevention of occupational diseases and improving the quality and life expectancy of workers. Underground mining of iron ore safe work deadlines when working under dust conditions 1.25–5 years, under noise — 1.5 months – 1.3 years, in heating microclimate is 10–13 years. In open pit mining of iron ore under the influence of dust safe working periods be 1.25–2.5 years, when working under conditions of noise exposure — from 5 days to 12.6 years. In metallurgical production because of exposure to noise safe working periods from 1.5 months to 1.3 years, when working under conditions of dust — 1.25–5 years. When working in a heating microclimate, safe working periods are from 7 to 17 years depending on microclimatic conditions in the workplace. Studies show the need for improvement of hygienic and preventive measures in the workplaces to improve working conditions and reduce the levels of harmful production factors.
