A recent report showed that Kathmandu has experienced increase in air pollution by 50-60 per cent in the last 15 years. On January 5 this year, Kathmandu suffered the worst air quality among the cities of the world, even higher than Bishkek of Kyrgyzstan and New Delhi. This intensifying fact has a negative impact on various environmental aspects, which in similar length affects the quality of life of both living and non-living things.

Indeed, besides having a huge impact on human health, air pollution is equally a key factor in the degradation of surfaces of building structures.

For this matter, we need to understand that the destruction of buildings and monuments caused by air pollution may be rapid or gradual. But this invisible killer is a definite hazard for any type of building.

It is difficult to see and measure from year to year, and such gradual damage on buildings is stealthy, and often no different in appearance from the damage caused by natural events.

But the ultimate impact will be seen on the buildings, and, in turn, on humans. Both will face harm equally in the future as the intensity of air pollution increases. These being the spatial elements that complete our city, the effect on the built environment caused by air pollution can't be overlooked.

Air pollution has been a global problem of the 21st century.

Humans protect and even improve the environment in many ways. We have the power to improve as well as damage the built environment.

Thus, the issue has arisen - which should be given priority, human health or buildings? Sometimes these two interests are compatible with each other.

When human health is concerned, no doubt, its protection should be emphasised.

But the facts are that there is a significant inter-relation between people and infrastructure: buildings meet not only functional and creature comforts, but also spiritual comfort.

In addition, any building is not just an erected structure of materials but more than that. It is something that gives us the feelings of comfort everywhere, and it carries stories.

In order to adequately understand this, it is necessary to consider how buildings and people mutually shape one another through their interactions, in particular social and historical contexts.

Hence, protecting buildings is crucial. Greater attention needs to be given to understanding building materials use and infrastructure, and value, not as intrinsic physical properties, but rather as indissolubly social and material components of buildings-in-use.