21.   Although drinking milk meant greater exposure, breathing contaminated air or eating leafy vegetables and eggs also raised the risk.

22.   A third of us breathe air which endangers our health.

23.   After eight hours on a job, they were back on the streets, dodging sports cars, fleeing ill-tempered dogs, breathing polluted air.

24.   Breathing air with a high oxygen content, enthusiasts say, has health benefits that range from boosting energy and the immune system to relieving headaches and stress.

25.   But does loading up on oxygen provide a lift or do any more for the body than just breathing the air in the street?

26.   But it does not cause us to breathe an air that we have never breathed before.

27.   But it is possible to fly to the North and South poles and to breathe the air there without risk.

28.   But still they breathe the air of plenitude.

29.   Conservation, everyone agrees, is the key to keeping the lights on and breathing healthier air.

30.   Do not breathe air!