1.   He took off his hard hat and wiped his brow, after checking for scaffolding.

2.   However, cyclists make a good example because they too are starting to wear hard hats.

3.   I had to put my hard hat on and go to work.

4.   If hydrogen sulfide or some other poisonous gas is detected, Donahue dons an airtight breathing device and a hard hat.

5.   Now the unions are softening up their hard hats.

6.   When no vapors are present, he simply wears the hard hat.

7.   Hard hats must be worn on the construction site.