The persistent haze over many of our cities is a reminder of the polluted air that we breathe. Over 80% of the world’s urban population is breathing air that fails to meet World Health Organisation guidelines, and an estimated 4.5 million people died (26)_____ from outdoor air pollution in 2015.
Globally, urban populations are expected to double in the next 40 years, and an extra 2 billion people will need new places to live, as well as services and ways to move around their cities. What is more important, the decisions that we make now about the design of our cities will (27)_____ the everyday lives and health of the coming generations. So what would a smog-free, or at least low-pollution, city be like?
Traffic has become (28)_____ with air pollution, and many countries intend to ban the sale of new petrol and diesel cars in the next two decades. But simply (29)_____ to electric cars will not mean pollution-free cities. The level of emissions they cause will depend on how the electricity to run them is (30)_____, while brakes, tyres and roads all create tiny airborne (31)_____ as they wear out. Across the developed world, car use is in decline as more people move to city centres, while young people especially are (32)_____ for other means of travel. Researchers are already asking if motor vehicle use has reached its (33)_____ and will decline, but transport planners have yet to catch up with this (34)_____, instead of laying new roads to tackle traffic jams. As users of London’s orbital M25 motorway will know, new roads rapidly fill with more traffic. In the US, studies have shown that doubling the size of a road can (35)_____ double the traffic, taking us back to the starting point.
