With pollution of agricultural fields by plutonium at a level of more than 3.7 kBg/m2 and cesium more than 7.4 MBq/m2 radionuclide levels in tractor cabin can exceed the permissible level. However field work being seasonal, annual level of inhaled radionuclides does not exceed the permissible limit. Actually the equivalent dose for the lungs does not exceed just few mSv under conditions of agricultural production.