Question 3 of 7: Airborne Contaminants and Chemical Health Effects

Question 3: Airborne Contaminants and Chemical Health Effects (20 marks: 7/7/6)

Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.

(i) Types of Airborne Contaminants

• Dusts — solid particles generated by grinding, crushing, sanding (e.g., silica, wood dust).
• Fumes — fine solid particles formed by condensation of vaporized solids, typically metals (e.g., welding fume).
• Mists — fine liquid droplets suspended in air (e.g., spraying, oil mist).
• Smoke — carbon/soot particles from incomplete combustion.
• Gases — formless fluids that fill their container (e.g., carbon monoxide, chlorine).
• Vapours — gaseous phase of substances normally liquid/solid at room temperature (e.g., solvent vapours).
• Fibres — elongated particles (e.g., asbestos). (Biological aerosols may also be present.)

(ii) Health Effects of Chemicals

• Irritants — inflame skin, eyes, respiratory tract.
• Corrosives — destroy tissue on contact.
• Asphyxiants — simple (displace oxygen) or chemical (block oxygen use, e.g., CO).
• Sensitizers — provoke allergic reactions after repeated exposure.
• Systemic toxins — damage specific organs (liver, kidney, nervous system).
• Carcinogens, mutagens, teratogens/reproductive toxins — cause cancer, genetic damage, or harm to the fetus/reproduction.
• Effects may be acute or chronic, local or systemic, and depend on toxicity, dose, and route/duration of exposure.

(iii) Main Routes of Entry

• Inhalation — breathing in airborne contaminants; the most common and rapid route (large lung surface, direct to bloodstream).
• Skin/eye absorption or contact — some substances penetrate intact skin or damage it/the eyes on contact.
• Ingestion — swallowing, usually via contaminated hands, food or smoking; less common in industry.
• Injection — through a puncture or high-pressure injection past the skin barrier; less common but serious.
• Controls target the route: ventilation/respirators for inhalation, gloves/clothing for skin, hygiene practices for ingestion.