This study investigated one of the main harmful factors at work, namely the impact of noise exposure on employees. The study was conducted in several stages. At the first stage, an on-site measurement was carried out using a calibrated sound level meter and a special smartphone application in the immediate vicinity of the ore grinding mill. It was found that the noise level is not constant. At the second stage, a mathematical dependence of the noise measurement results on the mill operating time was obtained to compare the measurement accuracy of the sound level meter and the app. As a result, it was determined that the application has sufficient accuracy compared to the calibrated instrument. The third stage resulted in the calculation of the risk of hearing loss for employees from noise exposure at workplaces based on the measurements of the calibrated sound level meter. The calculations showed that the level of this risk is high. At the fourth stage, personal protective equipment was selected using the relevant guidelines from NIOSH and EU-OSHA, as well as considering the results of field measurements, the maximum permissible noise level established by state sanitary standards, and the level of hearing loss risk.