It was found that in cutting deep holes, with an increase in the temperature from 20 to 80 degrees C, the content of harmful components: 9- and 2-methylanthracene, 3-methylphenanthrene, etc., in oil-based MR-3K coolant (CL) decreases by 15-25%, i.e., they enter the air of the working zone. The necessity of additional treatment of CL to remove polycyclic aromatic hydrocarbons to minimize the harmful effect on humans and the biosphere as a whole is demonstrated.