People in Kathmandu joke that the face mask has now become part of the national dress – an indispensable accessory in an effort to protect themselves from the dust. Nepal has the worst air quality in the world, according to the Environmental Performance Index. (Photo by Pete Pattisson/The Guardian)

These kaleidoscopic images are the work of one persistent photographer’s efforts to capture vibrant hues at the exact moment a wave breaks. Ryan Pernofski‘s stunning shots feature brilliant yellows, reds, blues and purples as an array of sunlight hits the water at the perfect time. What’s even more impressive: Ryan, a 27-year-old Australian, began shooting his popular masterpieces without using a professional camera, taking his iPhone out into the water instead. Ryan began experimenting with this method in 2012, using an underwater housing to protect his phone, as he could not afford a professional camera. (Photo by Ryan Pernoski/Caters News Agency)

The British Ecological Society has announced the winners of its annual photography competition, Capturing Ecology. Taken by international ecologists and students, the winning images will be exhibited at the society’s joint annual meeting in Ghent in December. Here: Overall runner-up; Toucan, Mark Tatchell. (Photo by Mark Tatchell/British Ecological Society)

A woman reacts after performing Otonamaki, which translates as “adult wrapping”, a new form of therapy where people are wrapped in large swaddling cloth to alleviate posture problems and stiffness, at a session in Asaka, Saitama prefecture, Japan, February 4, 2017. (Photo by Toru Hanai/Reuters)

Annual celebration of Dinagyang festival of Iloilo, Philippines. (Photo by Raniel Jose Castañeda/Sony World Photography Awards)

As a social experiment, journalist Esther Honig contacted Photoshop artists across the world and told them to make her beautiful, and they did. Honigh said she was surprised by how her image was altered, saying the process has greatly changed her perception of beauty. Photo: “Before & After” project: Greece. (Photo by Esther Honig)

Some are in it just for the money, others to help buy a meal. Then there are those who trade for fun or to spend time among friends. Millions of investors – pensioners, security guards, high-school students – dominate China's stock markets, conducting about 80 percent of all trades. Retirees gather in brokerage houses dotted around China also to enjoy some company and savour the air conditioning on hot days. Some start as young as 13, trading from home with an eye on future careers in finance. Winning isn't guaranteed. This year, among the most turbulent in China's financial history, its stock markets more than doubled in the six months to May, only to crash amid concerns that growth in the country, which makes everything from cars to steel, is slowing faster than previously thought. (Photo by Aly Song/Reuters)

“Strike Through The Mothership”. Every May for the last 3 years I have driven down to Tornado Alley to capture some amazing storms. This supercell held so much promise to drop a tornado but one small shift in the atmosphere and all that it produced was an extreme lightning show. Photo location: Broken Bow, Nebraska. (Photo and caption by Vanessa Neufeld/National Geographic Photo Contest)