Aim. To evaluate the non-carcinogenic hazard posed by exposure to suspended ultrafine industrial aerosol particles among workers of a machine-building enterprise.

Materials and methods. The content of suspended ultrafine particles was analyzed using a scanning spectrometer NanoScan 3910. The chemical composition was assessed by optical emission spectrometry with inductively coupled plasma. To assess adverse non-carcinogenic effects, hazard quotients (HQs) were calculated, and the risk level was determined depending on the suspended particle using the proposed new methodology.

Results. The study has revealed that suspended particles comprised chemical elements with varying densities. Based on this, HQs were calculated and ranked for workers at the machine-building enterprise. HQs from the impact of suspended ultrafine particles with a density ≥6 kg/m3: 4.88 – for furnace operators, 4.44 – for welders, 2.63 – for cutters, 2.16 – for grinders. HQs from the impact of suspended ultrafine particles with a density ≤6 kg/m3: 2.44 – for furnace operators, 2.22 – for welders, 1.32 – for cutters, 1.08 – for grinders.

According to the proposed methodology, for furnace operators, particles of 11 nm and 15 nm posed the greatest hazard. For manual electric welders, 11 nm particles were critical, as well as larger particles in the range 64–154 nm. Grinders faced the highest risk from exposure to particles of 15–48 nm, while for cutters, the most dangerous were particles of 48 nm and larger ones in the range 154–205 nm.

Conclusions. The calculated hazard quotients for suspended ultrafine particles exceeded safe limits at all workplaces, which is not within acceptable parameters given the high probability of harmful effects. According to the proposed methodology, hazard levels were determined for each workplace based on particle size to guide the implementation of targeted preventive measures.