AWS Certified Welding Inspector — FundamentalsSafetyHard
A welder is working in an area where oxygen-acetylene cutting is being performed simultaneously with electric arc welding. The inspector notices a distinct, pungent odor. What gas is MOST likely responsible for this odor, and what is its primary health concern?
- AArgon; displaces oxygen and causes asphyxiation.
- BCarbon Monoxide; interferes with oxygen transport in blood.
- CNitrogen Dioxide; causes lung damage and delayed effects.
- DOzone; irritates the respiratory system.
Show answer & explanationAnswer & explanation
Correct answer: D. Ozone; irritates the respiratory system.
The intense UV radiation from electric arc welding (especially in combination with cutting) can convert oxygen in the air into ozone (O3), which has a distinctive pungent odor. Ozone is a strong respiratory irritant and can cause significant lung damage.
Why the other options are wrong
- A. Argon is an inert gas, odorless, and its primary concern is oxygen displacement, not a pungent odor or direct toxicity.
- B. Carbon monoxide is odorless and colorless, making a pungent odor unlikely. While it interferes with oxygen transport, the symptom doesn't match the odor.
- C. Nitrogen dioxide is formed when nitrogen and oxygen are exposed to high temperatures, such as in arc welding. It can have a sharp, irritating odor, but 'pungent' more commonly describes ozone, and its health effects are indeed lung damage and delayed symptoms (pulmonary edema). However, given the 'distinct, pungent odor' specifically, ozone is a very strong candidate.
Ozone from Arc Welding
Ozone (O3) is a gas formed by the reaction of atmospheric oxygen with the intense ultraviolet radiation produced during arc welding, recognizable by its pungent odor and causing respiratory irritation.
- Formed by UV radiation from arc welding.
- Pungent, bleach-like odor.
- Causes respiratory irritation and lung damage.
Memory trick: UV light makes ozone, a pungent smell it has shown, irritating lungs, making breathing moan.