29,000 deaths from air pollution? It's complicated

As the World Health Organisation (WHO) yesterday released data on air pollution in 1,600 cities, the Lib Dems and Labour both repeated the claim that an estimated 29,000 people in the UK die because of the pollution.

As we found earlier in the year, the estimate isn't quite what it seems.

The researchers behind the figure actually found that the pollution probably contributed to, but were not the sole cause of, a far greater number of deaths.

They calculated that the damage to life expectancy this caused was "equivalent" to around 29,000 deaths.

It should also be noted that the figure applies to 'PM2.5' pollution, meaning pollution involving particles of 2.5 micrometres or less while the WHO data is broken down by both PM2.5 and PM10 pollution.