India's capital, New Delhi, has the worst air quality of any city in the world, according to figures published by the World Health Organisation.
The WHO measured the average levels of harmful particles known as PM2.5s to try to gauge which urban areas had the most dangerous pollution levels.
Indian cities occupied the top four places on the global list, and 13 out of the top 20 dirtiest cities.
There were three Pakistani cities in the top 20, along with the Qatari capital, Doha and cities in Iran, Turkey and Bangladesh.
The UK's governing body for cycling has said high levels of air pollution in some British cities are further evidence of the need to expand cycling.
It follows a study from the World Health Organisation that found nine British cities and towns had unsafe levels of air pollution.
Martin Key, campaigns manager for British Cycling, said: "With almost daily news stories about worrying levels of air pollution, it is clearer than ever that more cycling is the answer to many of the problems we face in Britain today."
"If local and national government put sustained and targeted investment into improving our roads and making them fit for cycling, we will without doubt create healthier, happier communities and more pleasant places to live," he added.
The World Health Organisation has warned that air pollution is "getting worse".
Only 12% of residents in cities that reported on air pollution were living in areas that comply with the WHO's guidelines.
The WHO estimates that in 2012 air pollution was responsible for the deaths of 3.7 million people around the world.
Although several British cities have been named as breaching safe air quality levels, cities in countries such as India, China and Pakistan have much higher levels of pollution.
Dr Flavia Bustreo, WHO's assistant director-general for family, children and women's health, said many cities were now "so enveloped in dirty air that their skylines are invisible".
London, Birmingham and Leeds are among nine British towns and cities which have come under fire for breaching safe levels of air pollution
The World Health Organisation (WHO) also named Chesterfield, Nottingham, Sheffield, Southampton, Stoke-on-Trent and Thurrock as having problems with levels of dangerous particles called PM10s.
However some areas, including Manchester, Bournemouth and Northampton, did not provide data for levels of PM10s.
People living in polluted areas are at greater risk of respiratory disease and other health problems.
Public Health England has said that air pollution was responsible for 25,000 deaths in England in 2010.
Large areas of the sea bed are covered with human litter such as plastic bags, bottles and discarded fishing nets, scientists have discovered.
Researchers looking at samples from all over the world found that plastic was the most common litter, accounting for 41% of the waste on the seabed.
Dr Kerry Howell from Plymouth University's Marine Institute said the study showed litter was present "in all marine habitats, from beaches to the most remote and deepest parts of the oceans".
The Government is set to spend £500m to encourage more drivers to use electric cars.
Under the proposals people can get grants of up to £5,000 towards the cost of an electric vehicle.
Deputy Prime Minister Nick Clegg will also set out £100m of extra investment in research and development to help the UK remain at the forefront of the new technology.
Around 500 wildlife areas could be at risk from the HS2 high speed rail line, conservationists have warned.
The Wildlife Trusts called for a £130m investment to create new green areas over the length of the new line.
Among the areas affected by the new line are 43 ancient woods and nine Wilflife Trust nature reserves.
A fifth of gardeners admit to throwing snails over the fence into their neighbour's garden to get rid of them, a survey has revealed.
The poll for the Royal Horticultural Society found 80% of people will be heading into their gardens this Easter to tackle spring jobs such as weeding and mowing the lawn.
The survey of more than 1,500 people to mark National Gardening Week this week also found that good gardeners make good neighbours, with just 3% admitting to growing plants to block out their neighbours' gardens.
But while almost four fifths (78%) said they had never thrown a snail into their neighbour's garden, 22% admitted to the horticultural crime.
Non-native 'killer shrimp' and zebra mussels are "invading Britain" at a rate never seen before, a government watchdog says.Read the full story ›
The world has to move quickly "if it's serious about limiting temperature increase, Dr Rajendra Pachauri, of the Intergovernmental Panel on Climate Change told ITV News today.
Energy Secretary Ed Davey told ITV New correspondent Lewis Vaughan Jones that the report shows a very real threat, but denied that Government hasn't done enough to move towards more sustainable energy.