Breathtaking

SMOKING a whole packet of cigarettes in a day once or twice a year would certainly make someone feel ill, but probably would not kill him. Smoking even one cigarette every day for decades, though, might do so. That is the difference between acute and chronic exposure, and it is a difference most people understand. What they may not understand is that the same thing applies to air pollution.

On a day-to-day basis, the forecasts most cities offer turn red only when pollution levels rise to a point where they will cause immediate discomfort. That makes sense, for it lets people such as asthmatics take appropriate action. But it might also lead the unwary to assume, if most days in the place he inhabits are green, that the air he is breathing is basically safe. This may well not be the case. In London, for example, a study published last year by researchers at King’s College suggested air pollution shortens the city’s inhabitants’ lives by nine to 16 months.

To investigate the matter, The Economist crunched a year’s worth of data collected from May 2015 onwards in 15 big cities. They were gathered…Continue reading
Source: Economist