Horses graze in the vast heart of Mongolia’s eastern steppe, which stretches across 285,000 sq km (110,000 sq miles)

Baterdene Tuvshintur, a herder, outside his homestead in Khentii province with his wife, Baigal Batulzi, and one of their children

Baterdene, centre, tends to the stove in his family’s ger – better known by the Russian term ‘yurt’ – alongside his wife, Baigal, his son, and a friend, Gurjav Tuvshintur, governor of the province

Horses walk along a road overlooking the smoggy skyline of Mongolia’s capital, Ulaanbaatar. Burning coal is the main cause of air pollution in the country

A street scene in Ulaanbaatar. Nearly half of the country’s population of 3.5 million now live in the world’s coldest capital city

Pupils play outside School No 151 in the Songinokhairkhan district in Ulaanbaatar. The school is heated by coal-fired boilers, which create air pollution indoors and outdoors

Batbold Vandon, School No 151’s caretaker, collects bags of coal for the boiler. The use of coal has led to a health crisis in the population, especially among the young

Enkhsin Munkhsareal in front of her ger. Extremely harsh winters, killing many livestock, have driven many herders into makeshift urban settlements

Batbold Vandon has to feed the boiler constantly to keep the school warm. He works in shifts with two other janitors so the furnaces are fed 24 hours a day

A man drags a cart of coal home in the Bayanzürkh district of Ulaanbaatar, where there are many informal settlements

Chinggis City is in the heart of the Mongolian steppe, in Khentii province. Formerly known as Öndörkhaan, it was renamed in 2013 as the birthplace of the 13th-century leader Chinggis Khan, better known in the west as Genghis, founder and first khan of the Mongol empire. Provincial cities also have a pollution problem

A main road in Ulaanbaatar, where the annual average temperature is about 0C (30F) and can drop to -40C (-40F) in the winter

Early morning smog in the Songinokhairkhan district of Ulaanbaatar

Steam from underground pipes mixes with traffic fumes and smoke from coal-burning stoves to produce a foggy haze in the capital

Informal housing in Ulaanbaatar’s Bayanzürkh district. Due to a temperature inversion, when a layer of warm air forms above cooler air, smog remains trapped above the city for much of the winter

Enkhsin Munkhsareal, a single mother, with her two-year-old daughter Narmandakh, beside a coal-fired stove in their ger

Batkhuyag Badamkhand, a herdsman, drives another horse alongside as he rides on the steppe. As well as being essential to the nomadic lifestyle, horses hold a sacred place in Mongolian culture and are a symbol of national heritage

Batkhuyag at his homestead in Murum Soum, Khentii province. The climate crisis is making the traditional nomadic lifestyle very hard for herders

Batkhuyag tends to his livestock. Mongolian herders traditionally raise horses, camels, yaks, sheep and goats. As they are so integral to their culture and provide essential resources, they are referred to as the ‘five jewels’