When is compressed air permitted for cleaning purposes?

Using compressed air for cleaning purposes is permissible when it is reduced to a pressure of less than 30 pounds per square inch (p.s.i) and combined with effective guarding. This regulation is crucial because high-pressure air can propel dust, debris, and other materials at dangerous speeds, posing a risk of injury to operators and bystanders. Reducing the pressure minimizes this risk, making it safer for cleaning tasks.

Effective guarding refers to safety measures or equipment that protect workers from potential hazards related to airborne particles and debris. By ensuring that the pressure is kept below this threshold and implementing appropriate safety measures, the likelihood of injuries resulting from the use of compressed air can be significantly reduced.

The other options are not suitable because they either imply unsafe practices or do not meet necessary safety standards for the use of compressed air in cleaning.