Inventor Chris Turner has completed a crowdfunding drive and is now selling what he says is “the world’s smallest” hand-held pollution monitor. The Crouch End dad was inspired to create the “BREATHE:Smart” device by the difficulty of monitoring the air quality around his young family.

He raised $25,000 dollars on IndieGoGo to finance the invention.

Last winter, while fundraising was ongoing, he told this newspaper the idea was inspired by the impracticality of measuring pollution.

Chris said: ""As a parent living in a busy city, I am constantly concerned about the

negative effects of air pollution on my family's health."

The watch-like device - which costs £99 - can be attached to prams or indoor services to measure PM2.5 particules in the air.

These can be given off by vehicles, but also by seemingly innocuous tasks such as cooking indoors.