Subtopic: Human engineering and safety considerations in design of tractor and agricultural implements
Question Statement:
Under standard occupational health regulations (OSHA / Indian Standard IS 12180), the maximum permissible continuous A-weighted sound level ($L_{\text{eq}}$) at the tractor operator's ear level for an 8-hour daily exposure without hearing protection is:
Options:
(A) $65\text{ dBA}$
(B) $85\text{ dBA}$
(C) $105\text{ dBA}$
(D) $125\text{ dBA}$
Answer Key:
B
Step-by-Step Solution & Explanation
- **Occupational Noise Exposure Standard:**
- The standard 8-hour time-weighted average (TWA) permissible exposure limit is **$85\text{ dBA}$** (or $90\text{ dBA}$ in older regulations).
- Tractors without cabs often generate $88\text{--}95\text{ dBA}$, exceeding safe limits and necessitating earplugs or acoustic cabs.