Advert for protection against dengue fever in Phitsanulok, Thailand

Advert for protection against dengue fever in Phitsanulok, Thailand in June 2016

A billboard urging syphilis treatment on Commercial Road, Prahan, Melbourne

A billboard urging syphilis treatment on Commercial Road, Prahan, Melbourne, in September 2010

Smoking causes mouth and throat cancer

Empty packet of cigarettes at the University of Canberra in November 2010. Serious health warning. Does anyone listen

Erradicate mosquitos

An mosquito eradication sign at the Big Buddha (Tian Tan Buddha) on Lantau Island, Hong Kong in July 2009

Don't feed the pigeons

A do not feed the pigeons sign photographed in Hong Kong in July 2009. They are terrified of bird flu.

Beware the birds

Beware of birds sign at the Hong Kong Botanical Gardens, July 2009.