Question

How is the Taj Mahal affected by air pollution?

Answer 1

• The type of pollution which affects the Taj Mahal in Agra to a greater extent is air pollution.
• It is affecting Taj Mahal by corroding it and yellowing its marble.
• The major threat to the Taj Mahal is the acid rain.

Acid rain:

• When atmospheric pollutants like oxides of nitrogen and sulphur react with rainwater and come down with the rain, then this results in acid rain.
• Acid rain is made up of highly acidic water droplets due to air emissions, most specifically the disproportionate levels of sulphur and nitrogen emitted by vehicles.
• It is often called acid rain as this concept contains many types of acidic precipitation.
• Sulphur dioxide and nitrogen dioxide undergo oxidation, and then they react with water resulting in the formation of sulphuric acid and nitric acid, respectively.

The following reaction will clarify the acid formation reaction:

$$\begin{gathered} 2{\mathrm{SO}}_{2\left(\mathrm{g}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}+2{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}\to 2{\mathrm{H}}_2{\mathrm{SO}}_{4\left(\mathrm{aq}\right)} \\ 4{\mathrm{NO}}_{2\left(\mathrm{g}\right)}+{\mathrm{O}}_{2\left(\mathrm{g}\right)}+2{\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{l}\right)}\to 4{\mathrm{HNO}}_{3\left(\mathrm{aq}\right)} \end{gathered}$$

• When the acid rain falls on the Taj Mahal the monument gets corroded.
• Taj Mahal is completely made of marble, acid rain reacts with marble to form a powder-like substance which is then washed away by the rain.
• This phenomenon is called marble cancer.