Nepalese police officers worship a dog during the dog festival as part of Tihar celebrations, also called Diwali, at the Central Police Dog Training School in Kathmandu, Nepal October 29, 2016. Dogs are worshipped to acknowledge their role in providing security during Tihar festival, one of the most important Hindu festivals that is also dedicated to the worship of the goddess of wealth Laxmi. (Photo by Navesh Chitrakar/Reuters)

A Nepalese woman pours milk as she offers prayers to the setting Sun on the banks of the Bagmati River during the Chhath Puja festival in Kathmandu, Nepal, Sunday, November 6, 2016. During Chhath, an ancient Hindu festival, rituals are performed to thank the Sun God for sustaining life on earth. (Photo by Niranjan Shrestha/AP Photo)

A close up of ornaments of centuries-old idols of Lord Buddha during the Pancha Daan, Five donation, festival in Bhaktapur, Nepal, 30 August 2016. Thousands of Buddhist pilgrims observe the main day of the Pancha Daan also known as a five summer gifts (rice, grain, salt, money and fruits) festival which is observes for world peace and human welfare. (Photo by Narendra Shrestha/EPA)

A Hindu devotee performs a ritual on Bagmati River during Kuse Aunse (Father's Day) at Gokarna Temple in Kathmandu, Nepal September 13, 2015. Hindus all over the country, whose fathers have passed away, come to the temple for worship, holy dips, and to present offerings on this occasion. (Photo by Navesh Chitrakar/Reuters)

Villagers use a makeshift bamboo bridge to move across flooded areas of Morigaon district in the northeastern Indian state of Assam August 20, 2014. The latest heavy rains have caused landslides and floods in many parts of India and Nepal, where at least 90 people have been killed since Thursday. (Photo by Reuters/Stringer)

Farmers take a break for lunch while celebrating National Paddy Day, also called Asar Pandra, that marks the commencement of rice crop planting in paddy fields as monsoon season arrives, in Kathmandu, Nepal, June 29, 2020. (Photo by Navesh Chitrakar/Reuters)

A young Hindu priest crawls under a cow as part of worship rituals during Tihar festival in Kathmandu, Nepal, Sunday, October 30, 2016. Cows are considered sacred to Hindus and are worshipped during Tihar festival, one of the most important Hindu festivals dedicated to the Goddess of wealth Laxmi. (Photo by Niranjan Shrestha/AP Photo)

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)