The massive migration of population to Ulaanbaatar results in difficulties for the city in accommodating this population and leads to the formation of ger districts in the area surrounding the city. The degraded sanitary, environmental and social conditions are more prone to the development of diseases. The proportion of the population aged 5-14 years reached 17.4 per cent at the end of 2016, compared with 26.3 per cent at the end of 1997.