Barely a day passes when we don’t read about the effects of global warming. In Singapore, we also worry about rising sea levels that pose an existential threat to low-lying islands. Climate change is the top worry of this generation.

Far less discussed – except when the haze pays us a visit – is the quality of the air we breathe. And yet bad air, which is routine in large parts of the globe, exacts a huge cost from the world we live in. It causes illnesses and health problems. It drags down productivity as people stay away from work or do not perform to their full potential. The price we pay for bad air – both indoor and outdoors – is not just a theoretical concept; it can be computed.