1.   After a number of years, the marble is badly stained.

2.   The building is structurally sound, but stones have been chipped and its brilliant marble has been stained by pollution.

3.   Indian environmentalists have focused increasingly on the Taj in recent years, saying polluting factories are causing damage and staining its marble.

4.   The Taj has recently been the focus of leading Indian environmentalists who say several polluting leather units and other factories are damaging the monument and staining its marble.

5.   The Taj has recently been the focus of leading Indian environmentalists who say polluting factories are damaging the monument and staining its marble.

6.   Top Indian environmentalists have said, however, that several polluting factories nearby are damaging the monument and staining its marble.