4. An employer shall not have a worker do work referred to in section 2 unless the worker, in accordance with this Regulation, has undergone the pulmonary health examinations during employment and holds a pulmonary health certificate.
Notwithstanding the foregoing, for a period of not more than one year, the employer may have such work done by a worker who, for a valid reason such as a layoff, was unable to undergo a new pulmonary health examination. The employer and the worker shall then take the necessary steps for the worker to undergo the examination as soon as possible.