Photo: Ali Moayedian

He told IRNA that air pollution covers the bridges with a detrimental layer causing acid rains and chemical reactions, which damage the body of the historical structures.

"Isfahan historical bridges are made of brick, tile, stone, traditional mortar and plaster.

"The materials used in the structures undergo continuous wear and erosion due to constant physical, chemical, mechanical and biological phenomena taking place in the nature," he added.

He noted that other natural factors such as intense fluctuations in temperature and humidity associated with the turn of seasons, flood, earthquake and sunshine also play a role in damaging the cultural monuments in the course of history.

"In the recent decades, due to industrialization of the city, detrimental factors such as water and air pollution as well as living creatures including man, animals and plants have also contributed to the growing trend of destruction of the ancient relics and have almost doubled it.

"Various species of creatures including animals, insects and birds such as mice, snakes, ants and migrant birds as well as plants such as moss also leave their destructive impact on the ancient bridges," he added.

More than 20 historical bridges have been constructed on Zaiandeh-Roud bridge in Isfahan, including Marnan, Allah Verdikhan, Choubi, Baba Rokneddin (Khajou) and Jey.