[Editorial] Air pollution—crossing borders
A silent killer responsible for more deaths than the number from HIV/AIDS, tuberculosis, and road injuries combined. A killer indifferent to political agendas and that cannot be contained by borders. Air pollution is associated with around 6·5 million deaths each year globally. While premature deaths from household air pollution are projected to decline from 3·5 million today to 3 million by 2040, premature deaths from outdoor pollution are set to rise from 3 million to 4·5 million in the same period.