Industrial hygiene: What is a representative threshold limit value (TLV) order of magnitude in parts per million for compounds such as ammonia, nitrogen dioxide, or phenol vapor in workplace air?

Introduction:
Threshold limit values (TLVs) guide acceptable airborne concentrations for occupational exposure. Different compounds have different TLVs, but their order of magnitude informs risk controls.

Given Data / Assumptions:

• We seek a representative order-of-magnitude value.
• Compounds cited: ammonia, nitrogen dioxide, phenol vapor.
• Standard 8-hour workplace exposure context.

Concept / Approach:
TLVs are substance-specific. Phenol commonly has a low TLV near a few ppm. Nitrogen dioxide has low ppm or sub-ppm guidance. Ammonia TLV is higher but still far below thousands of ppm for routine exposure.

Step-by-Step Solution:
Step 1: Compare typical TLVs: phenol low single-digit ppm; NO2 around sub-ppm to low ppm; ammonia tens of ppm.Step 2: The safest representative order-of-magnitude among the choices that applies to at least one cited chemical is single-digit ppm.Step 3: Therefore, 5 ppm best represents a conservative TLV magnitude in the set provided.

Verification / Alternative check:
Values like 1000 or 2000 ppm are immediately irritating or dangerous for many compounds and do not reflect TLVs.

Why Other Options Are Wrong:
100 ppm: too high for NO2 and phenol. 1000 and 2000 ppm: unrealistic TLVs. 0.05 ppm: too low as a general representative for the listed set.

Common Pitfalls:
Assuming a single TLV applies to all chemicals; always consult substance-specific tables.

Final Answer:
5 ppm