Due to a lot of specific reasons. Some of those are as : –
- From space google view when you would zoom into these cities, you would see that the color of these cities are grey. Because mother nature is absent or almost dead or very weak in those cities. A beautiful, green mother nature causes good air quality. A weak natural environment is unable to produce fresh and nicer quality air.
- Such conditions of mother nature have reached to this stage because there are no forests, no natural lakes, no reservoirs. Everything that was once is occupied. There are no terrestrial and aquatic fossils, no fauna, no plants to recycle air. So the natural entity to refresh the polluted smoky air emitted from factories and vehicles is missing.
- There are hardly any trees in those cities. If there are no trees, the quality of the air is poor.
- All that you see are completed or under-construction commercial buildings, completed or under-construction flyovers, water lines, gas lines, electric lines, and under-construction innumerable residential apartments. What all these large or huge pieces of masses or objects are liable to provide are dust, dust and dust. And dust is a major cause of poor air quality.
- In the past, and still, some governments are allowing to have factories and manufacturing units inside the cities. The smoke and air those entities eject are adequately liable for poor air quality.
- On the other hand, there are so many naked soils or clods in and around these cities. In developed countries, those naked clods or earth are covered with grasses (because their administration plant so). But, in these cities, these sort of places cause a lot of dust in the air.
- These cities’ infrastructures have been developed upon poor urban planning. Therefore, so many unnecessary buildings were erected by destroying green areas in the cities.
- Whatever was planned were not implemented accordingly due to inefficient bureaucracy with corruption.
- Whatever was planned could not see their end as the new administration changed the agendas and upon changing, instead of re-develop them, they have worsened those.
- Cutting of trees indiscriminately wherever they (government people, citizens, private companies) found that obstructed in erecting their buildings.
- The government failed to order the urban, commercial and residential areas developers that if trees are cut off, new trees must be replaced aside.
- The government failed to design that there should be enough space in the front, backyard and around the commercial and residential buildings where trees must be grown.
- Governments failed to protect natural streams, canals, ponds, lakes from land robbers and developer robbers.
- Rivers were polluted (could not back up for fresh air and became imbalanced) due to the extraction of industrial wastes. The government failed to order or advise the industrialists that the wastes should be extracted from dumping sites; even it has been too late for the governments to replace industrial zones outside the cities.
- There have been so many money makers (fake leaders, butcher businessmen, butcher industrialists) who made money at the expense of destroying mother nature. The government of the prime leaders failed to get rid of them from the administration.
- People voted wrong leaders, musclemen, bad guys who never cared for environmental safety and protection.
- The government indiscriminately gave permission to the fitness vehicles to move on the roads and streets inside the cities directly causing air pollution in these cities.
- After all, sometimes, polluted air is driven by fresh air from neighboring areas by some seasonal strong winds. Here, for these cities, nowhere to run. All the surrounded outskirts are full of industrial factories. Once strong winds blow, those bring further poor quality air.
Hope answered your question to some extent.
