Ulaanbaatar, the capital city of Mongolia, is one of the coldest and most polluted capitals during winter times. Despite the vast territory of Mongolia, 1.5 million people - half of the population - live in a small capital city which was designed for a population of only 400000. Air pollution in Ulaanbaatar reaches to hazardous level during the winter when residents in "ger" district start using coal-burning stove as a heater.

On 15th of May, 2019, the Government of Mongolia banned the consumption of raw coal and introduced "refined coal briquettes" in response to fighting the air pollution. Since the start of this policy, the smog in Ulaanbaatar city noticably decreased. Even the smog seemed to be partly disappeared visually since the ban of raw coal, it's important to check whether the actual particulate matter in the air decreased. Thus, this data visualization will mostly focus on how the ban on raw coal changed the air quality.

Particulate matter(PM) is a mixture of many harmful solid particles and liquid droplets in the air such as soot, smoke, metals, nitrates, sulphates, dust water and rubber etc. PM2.5 refers to the atmospheric particulate matter that has a diameter of less than 2.5 micrometres, which is about 3% of the diameter of human hair. PM10 are the particles with a diameter of 10 micrometers and they are also called fine particles. The air is considered safe to breathe when the quantity of PM2.5 in the air is 60 and PM10 is 100.

Note: Various studies show that PM2.5 has more severe health effects than PM10 as PM2.5 particles are so small that they can get deep into the lungs and bloodstream whereas PM10 particles can only pass through the throat, nose and surface of lung in the short term.

The data used in this data analysis is from air quality monitors in Ulaanbaatar. Location of these air quality monitors are shown on a map below.