Experts said pigeon droppings can cause serious diseases. "Pigeons and droppings can cause hypersensitivity pneumonitis, a type of lung disorder where acute inflammation occurs due to exposure to pigeons," said Dr Nikhil Modi from Delhi's Apollo Hospitals. Last year, an 11-year-old Delhi boy was diagnosed with hypersensitivity pneumonitis after prolonged contact with pigeon feathers and droppings.