The global air pollution 'blindspot' affecting 1 billion people

More than 100 of the world's poorest and most poorly governed countries have no or limited monitoring of the polluted air their citizens are breathing

More than 1 billion people live in countries that do not monitor the air they breathe, according to data released by the World Health Organisation (WHO).

Guardian analysis has revealed a great air pollution blindspot stretching the length of Africa, across large parts of the former Soviet Union, south-east Asia and the Caribbean. In 92 countries the monitoring equipment and staff needed to measure one of the world's most deadly pollutants - particulate matter (PM) - are simply not available.