The risk from any animal droppings or other residues is minimal, provided the dirt is cleared away immediately. The main concern is allergy since some animal material can cause asthma. There is no risk from lizards. Pigeon droppings, feathers, etc. should not be allowed to accumulate in a confined space where there is prolonged contact because, rarely, a fungus infection can occur if old material is breathed in from the resulting dust. Any further concerns or unusual fears should be addressed by psychologic de conditioning or anti-anxiety medications.