1.   Breathing air is cleansed of deadly carbon dioxide in a three-step process.

2.   Following the publicity surrounding acid rain damage to European forests at the time, clean air legislation helped to cleanse the air of sulphur.

3.   For anyone who is particularly worried about the threat, mobile filters, available commercially, will more quickly cleanse the air in individual offices.

4.   Needles catch dust and dirt, thus cleansing the air.

5.   Plants, on the other hand, cleanse the air of carbon dioxide and release much-needed oxygen and water.

6.   There is controversy over a TV commercial now running in California, with each side fighting to cleanse the air of something it finds offensive.

7.   An early morning rain and stiff wind Sunday cleansed the air of tear gas residue and businesses began reopening after shuttering their windows with plywood and sheet metal.