1.What are the main toxic substances in welding fumes?
Zinc oxide particles
This is a major culprit in causing acute illness. Inhaling large amounts of newly formed, tiny zinc oxide particles can trigger an acute occupational disease called "metal fume fever."
Other metal fumes and oxides
Besides zinc, welding fumes may also contain oxides of metals such as iron, manganese, chromium, and nickel from the steel substrate.
Manganese, in particular, can cause damage to the nervous system with long-term inhalation, leading to symptoms similar to Parkinson's disease (known as "manganese poisoning").
Gases generated during the welding process:
Ozone: Generated by the reaction of ultraviolet radiation from the electric arc with oxygen in the air; it strongly irritates the respiratory tract.
Carbon monoxide: Especially in processes such as MAG welding (magnetic arc welding), it is produced by the decomposition or incomplete combustion of shielding gases (such as CO₂).
2.What are the symptoms of acute poisoning?
Metal fume fever is the most common acute poisoning reaction after welding galvanized parts. Its symptoms are very typical, usually appearing 4-12 hours after exposure (especially in the afternoon or evening after get off work):
A metallic sweet taste in the mouth: This is the initial sign.
Dry throat, irritation, cough.
General weakness, muscle and joint aches: Feeling like a sudden, severe cold.
Headache, chills, fever: Body temperature may rise to 38-39°C or even higher.
Nausea, vomiting.
3.What are the consequences of welding galvanized materials for an extended period without adequate protection?
Chronic respiratory diseases: such as bronchitis, pneumonia, and decreased lung function.
Nervous system damage: mainly related to manganese accumulation.
Increased cancer risk: According to the International Agency for Research on Cancer (IARC) classification, welding fumes are classified as Group 1 carcinogens, meaning they are "carcinogenic to humans."
4.What engineering and technical controls must be implemented?
Local exhaust ventilation: This is the most crucial and effective measure. Use a welding fume extractor (fume extractor arm), placing the suction port as close as possible to the welding point (usually within 15-30 cm) to capture and filter the smoke as it is generated.
General ventilation: Ensure good overall ventilation throughout the workshop to dilute the concentration of smoke in the air.
5.What personal protective equipment is required?
Respiratory Protection: In situations where ventilation cannot completely eliminate fumes (e.g., working on large workpieces), a dedicated particulate respirator must be worn.
Preferred: Powered air-purifying respirator (PEPR), which provides cleaner air and better comfort.
Secondary choice: Higher-grade dust masks (e.g., meeting NIOSH N95, R95, or P95 standards, or the Chinese KN95 standard). Ordinary gauze masks are completely ineffective.
Protective clothing, gloves, and welding face shields: Protect against skin contact and arc radiation.