From Ghana to Argentina and London, air pollution is a problem that people want to solve.
As part of the BBC’s So I Can Breathe series, people have been sharing their tips on how to improve the air around them.
For Phoebe, Joylen and Verity, from London, the answer is to stop cutting down trees.
Students at 50 London schools breathe air that exceeds legal pollution limits.
“Toxic air audits” have been announced by the mayor of London to combat the problem.
According to the US Forest Service, trees reduce urban air pollution by only up to 1%, but even this can have significant health benefits.
Areej also wants to plant trees in urban areas of Damascus to improve air quality.
Wood-burning stoves are a cause of high household air pollution levels and have been linked to four million premature deaths annually, according to the World Health Organization.
Adboulie Sey thinks they should be banned from Gambia and solar energy promoted instead.
A tax on wood stoves is another solution, suggested by Karen Baines on Twitter.
Improving how we travel is a common concern.
Adelaide Arthur wants to use her bike more in order to cut pollution in Accra.
Swapping driving for cycling can reduce the number of vehicles on the road emitting pollutants such as carbon monoxide.
Robert Singleton suggests a ban on diesel powered vehicles would go some way to reducing pollution.
Improved public transport is also proposed by Maria Innes in Buenos Aires, and echoed by Oscar Soria, in New York.
Mike Hall thinks government schemes to support people buying hybrid or electric cars is one way to encourage more environmentally friendly transport.
And finally Joab Frank Chakhaza wants to limit car imports in Malawi.
So I Can Breathe
A week of coverage by BBC News examining possible solutions to the problems caused by air pollution.