After the first trigger of elevated respirable dust, when must a follow-up sample be collected?

• A. Immediately
• B. Within 2 weeks
• C. Never
• D. Within 3 months

Answer: (B)

After a trigger of elevated respirable dust, the goal is to verify whether the exposure remains elevated and whether control measures are effective. The follow-up sample is required within two weeks so the situation can be confirmed promptly and corrective actions, if needed, can be implemented without unnecessary delay. Collecting immediately wouldn’t give enough time for any changes to influence sampling results, while waiting months would leave workers exposed longer than acceptable. A too-long interval also undermines the purpose of quick verification. So, a follow-up within two weeks best balances timely risk confirmation with practical measurement needs.