Once the pigeons have left, it is recommended to carry out a vigorous cleaning and disinfection of the surfaces to avoid any further damage. Indeed, the droppings and guano left by pigeons contain high amounts of nitric acid. A substance which, if left untreated for too long, can seriously damage surfaces such as wood, concrete etc. In addition, the droppings left by birds constitute a major health risk. Indeed, bird droppings contain a large number of bacteria, fungi and pathogenic micro-organisms responsible for many infectious diseases such as Psittacosis, Histoplasmosis or even avian flu which can be very severe, particularly in people most vulnerable (pregnant women, children, the elderly, etc).