What do I do… if rattles sound the gas alarm?#

What do I do... if rattles sound the gas alarm? If I am out of doors, I put on my gas mask, cover up my neck and hands, and take cover as quickly as possible. I do not look up. If I am indoors, I put on my gas mask, and shut all doors and windows. If I feel a smarting sensation, or think I smell gas, even when I first put my mask on, I do not take the mask off. The discomfort will pass off in a few minutes. I keep my mask on and stay under cover till I hear the gas 'all clear' sounded on handbells.