A Chinese tourist wears a face mask besi...A Chinese tourist wears a face mask beside the Forbidden City as heavy air pollution continues to shroud Beijing on February 26, 2014. Beijing's official reading for PM 2.5, small airborne particles which easily penetrate the lungs and have been linked to hundreds of thousands of premature deaths, stood at 501 micrograms per cubic metre.   AFP PHOTO/Mark RALSTONMARK RALSTON/AFP/Getty Images

Mark Ralston/AFP

A Chinese tourist observes the Forbidden City as heavy air pollution continues to shroud Beijing.

Workers construct a Carnival float in the Grande Rio Samba School warehouse on February 24, 2014 in Rio de Janeiro, Brazil. Carnival officially begins on February 28 but pre-festivities have already begun

Mario Tama/Getty Images

Workers construct a Carnival float in the Grande Rio Samba School warehouse in Rio de Janeiro, Brazil. Carnival officially begins on February 28 but pre-festivities have already begun.

enice Carnival 2014...VENICE, ITALY - FEBRUARY 25:  Three people dressed in Carnival Costumes pose at the Doge Palace on February 25, 2014 in Venice, Italy. The 2014 Carnival of Venice will run from February 15 to March 4 and includes a program of gala dinners, parades, dances, masked balls and music events.  (Photo by Marco Secchi/Getty Images)

Marco Secchi/Getty Images

Three people dressed in Carnival costumes pose at the Doge’s Palace on Tuesday in Venice. The 2014 Carnival of Venice runs until March 4 and will include a program of gala dinners, parades, dances, masked balls and music events.

members of Indiaís Dongria tribe watch animal sacrifice during the two-day long Niyamraja Festival atop the Niyamgiri hills near Lanjigarh in Kalahandi district, Orissa state, India. Every year, members of this indigenous group celebrate this festival sacrificing animals and birds in worship of their deity. (AP Photo/Biswaranjan Rout)

Biswaranjan Rout/AP

Members of India’s Dongria tribe watch an animal sacrifice during the two-day Niyamraja Festival atop the Niyamgiri hills near Lanjigarh in Kalahandi district, Orissa state, India. Every year, members of this indigenous group celebrate this festival sacrificing animals and birds in worship of their deity.

Eve Muirhead, Claire Hamilton, Anna Sloan, Vicki Adams...Britain's skip Eve Muirhead celebrates after beating Switzerland in the women's curling bronze medal game at the 2014 Winter Olympics

Wong Maye-E/AP

Britain’s skip Eve Muirhead celebrates after beating Switzerland in the women’s curling bronze medal game at the 2014 Winter Olympics, in Sochi, Russia

ranian President Hassan Rouhani (L) del...Iranian President Hassan Rouhani (L) delivers a speech during a rally in Tehran's Azadi Square (Freedom Square) to mark the 35th anniversary of the Islamic revolution on February 11, 2014. The 35th anniversary of the revolution that ousted the US-backed shah, comes as Tehran rides the wave of a landmark nuclear deal with major powers.

ATTA KENARE/AFP

Iranian president Hassan Rouhani delivers a speech on Tuesday during a rally in Tehran’s Azadi (Freedom) Square, to mark the 35th anniversary of the Islamic revolution

Bacteria portraits...Undated handout photo issued by The Big Bang UK Young Scientists & Engineers Fair of a portrait of Stephen Fry grown from his own bacteria. PRESS ASSOCIATION Photo. Issue date: Monday February 10, 2014. The 'bacteriographs' are made from a sample of the subjects bacteria - and have been grown by Zachary Copfer, an American microbiologist-cum-photographer. To make the Pop Art style images, Zachary cleverly exposes areas of a petri dish to radiation in order to stimulate the bacteria's growth. This creates a photograph grown entirely from the bacteria itself. Zachary is the only person in the world practicing this art, which he terms 'Bacteriography'. This is the first time his work has been brought to the UK. See PA story ARTS Bacteria. Photo credit should read: The Big Bang UK Young Scientists & Engineers Fair/PA Wire

The Big Bang UK Young Scientists & Engineers Fair/PA Wire

A portrait of Stephen Fry grown from his own bacteria, commissioned by The Big Bang Fair. The ‘bacteriographs’ are made from the subject’s bacteria and have been grown by Zachary Copfer, an American microbiologist-cum-photographer. To make the Pop Art style images he exposes areas of a Petri dish to radiation in order to stimulate the bacteria’s growth Read more

An employee poses for pictures with an orchid display during a photocall for the 2014 'Orchids Festival' at the Royal Botanic Gardens in Kew, west of London, on February 6, 2014. The Festival opens to the public on February 8, 2014.

Ben Stansall/ AFP

Preparations for the Orchids Festival at the Royal Botanic Gardens in Kew, west London. The festival opens to the public on February 8

Spectators watch as waves break over the harbour wall at Porthcawl Wales, during a high tide today.

Matthew Horwood/Getty Images

Spectators watch as waves break over the harbour wall at Porthcawl, Wales, on Wednesday

Skiing freeriders Nicolas and Loris Falquet collaborated with photographer Jeremy Bernard and Swiss mountain sports manufacturer Mammut to create unique images by colouring the snow at their local ski fields of Les Marecottes, near Martigny, in south-western Switzerland. The Swiss brothers used eco-friendly coloured pigments and a futuristic atomizer to colour the snow over a period of 15 days to create 5 minutes of video and a portfolio of 13 extraordinary photos

Jeremy Bernard/Mammut for Photopress via AP Images

Skiing freeriders Nicolas and Loris Falquet collaborated with photographer Jeremy Bernard and Mammut to create unique images by colouring the snow at the local ski fields of Les Marécottes, near Martigny, in southwestern Switzerland