42 CFR §85.4

1. (a)Upon receipt of a request for health hazard evaluation submitted under this part, NIOSH will determine whether or not there is reasonable cause to justify conducting an investigation.
2. (b)If NIOSH determines that an investigation is justified, a NIOSH officer will inspect the place of employment, collect samples where appropriate, and perform tests necessary to the conduct of a health hazard evaluation, including medical examinations of employees.
3. (c)If NIOSH determines that an investigation is not justified, the requester will be notified in writing of the decision.