Introduction:
The current ecological situation is described by a rapid increase in air pollution through various chemical emissions.

Aim:
The study aims to define how the level of lead and chromium compounds affects the parameters of red bone marrow and blood in animals and how these processes depend on their age.

Material and methods:
To study the toxic intraday effect of heavy metals, a metal probe was used for combined priming of rats with lead acetate and potassium dichromate. The indicators were analyzed with the use of a cytogram, and the indices of the ratio between young and mature forms were calculated. The obtained factual material was subjected to computer processing with the calculation of the Student’s criterion and confidence intervals.

Results and discussion:
It was established that in young rats there is an accumulation of polychromatophilic cells with a large amount of hemoglobin, which leads to a violation of their maturation – with that, the subsequent stage of division passes very quickly, when, upon transforming into orthochromatic normoblasts, they pass into the blood after 15–20 h, forming a variant of terminal division. In old animals, there was a decrease in total bone marrow cellularity and severe anemia.

Conclusions:
After the experiments and profound analysis, the author of the study defined the difference of toxic effects on young and old animals.