Still rare only 20 years ago, the charismatic animals are in almost every UK river and a conservation success story

On a quiet Friday evening, an otter and a fox trot through Lincoln city centre. The pair scurry past charity shops and through deserted streets, the encounter lit by the security lamps of shuttered takeaways. Each animal inspects the nooks and crannies of the high street before disappearing into the night, ending the unlikely scene captured by CCTV last month.

Unlike the fox, the otter has been a rare visitor in towns and cities across the UK. But after decades of intense conservation work, that is changing. In the past year alone, the aquatic mammal has been spotted on a river-boat dock in London’s Canary Wharf, dragging an enormous fish along a riverbank in Stratford-upon-Avon, and plundering garden ponds near York. One otter was even filmed causing chaos in a Shetland family’s kitchen in March.

Levels during boarding and taxiing were far above those defined as high by the World Health Organization

A study has revealed the concentrations of ultrafine particles breathed in by airline passengers.

A team of French researchers, including those from Université Paris Cité, built a pack of instruments that was flown alongside passengers from Paris Charles de Gaulle to European destinations. The machinery was placed on an empty seat in the front rows or in the galley.