The house that 20,000 toothbrushes built

"For every five houses we build in the UK, the equivalent of one house in waste materials gets put into landfill," says architect Duncan Baker-Brown. 

To prove the point, Baker-Brown and his students at the University of Brighton have built a house almost entirely out of garbage. But is it the kind of place you might want to live in?

A Japanese oil tanker has exploded off the country’s south-west coast near Himeji port, leaving one of the eight people aboard missing, the country’s coast guard has said. Four others were severely injured in the accident on Thursday. Full story here

Photo: 5th Regional Coast Guard Headquarters/EPA

Nine Chinese cities suffered more days of severe smog than Beijing

Photographs of a smog-wreathed Tiananmen Square and the iconic headquarters of China Central Television dominated reports of Chinese pollution last year, but analysis shows nine other Chinese cities suffered more days of severe smog than the capital in 2013.

The worst was Xingtai, a city of more than 7 million people south-west of Beijing, which was hit by 129 days of “unhealthy air” or worse – the threshold at which pollution is considered at emergency levels – and more than twice as many days as the capital experienced. Read more

Photo: China Stringer Network / Reuters

Flooding crisis hits the Thames as political row worsens and Environment Agency warns that “hundreds homes likely to be flooded”. Read today’s summary

Above: A girl and her dog get around by canoe in Datchet, Berkshire. Photograph: Andy Rain/EPA

Britain’s only Green party MP Caroline Lucas arrested at anti-fracking protest

What advantages do highly sophisticated racing machines give the cycling pros? To find out, we pit a Guardian journalist on a £6,000 Tour de France bicycle against elite national-level rider Iain Cook on a variety of less advanced machines, including a Dutch shopping bike and a London hire bike. Who will win? Peter Walker reports from Herne Hill Velodrome in south London

The clearest lake in the world: Blue Lake, on New Zealand’s South Island

The visibility of distilled water is about 80 metres. Blue Lake, on New Zealand’s South Island, clocks in at 76 metres. Here are the first-ever photos of this newly discovered natural wonder, taken by Klaus Thymann of Project Pressure and supported by New Zealand Department of Conservation and New Zealand Tourism.

Photograph: Klaus Thymann /Project Pressure

'A tractor on a field in the South Downs near Brighton prepares for a late winter sowing'. From seeds to shoots – your best pictures on this week’s theme, sowing

Photograph: Finn Hopson

One tree, one year, one photographer…

Using his iPhone 4S, Mark Hirsch photographed a tree in Platteville, Wisconsin, every day from 24 March 2012 until 23 March 2013, capturing a year-long snapshot of life in and around the ancient oak:

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Photographs: Mark Hirsch/PSG