According to research by University College, London, such is the concentration of dust particles, that travelling on London’s Underground for 40 minutes is the equivalent to smoking two cigarettes.

Wolves have only one breeding season per year – in the winter. They have their puppies in late April or early May. They have their puppies in an underground hole, or den. There are usually four to six puppies in a litter. The puppies grow up fast and are their adult size by the end of their first winter. They are grown up by the time they are two years old.