The Earth Summit of Rio de Janeiro, also known as the United Nations Conference on Environment and Development (UNCED), was held in Rio de Janeiro from 3 to 14 June 1992. It resulted in the convention on biodiversity, a multilateral treaty. Three major goals were addressed in this convention which included: conservation of biodiversity; sustainable use of its components; and the fair and equitable sharing of benefits arising from the genetic resources. It was not related to air pollution.
So, the correct answer is 'Rio convention - air pollution'.