General pathology · Environmental pathology
Air pollution and occupational exposures !
- Topic
Polluted air outdoors, smoke from cooking fires indoors and dusts at work damage the lungs and the heart, and some cause cancer.
Updated 2026-11-01
What it is
The lung filters a huge volume of air every day. Fine particles, ozone and gases inflame the airways and reach the blood; mineral dusts are engulfed by macrophages that then drive fibrosis. Household smoke from wood or coal used for cooking is a major cause of disease in rural Latin America, and many workplace exposures cause specific diseases and cancers.
Key facts
- Carbon monoxide binds haemoglobin far more tightly than oxygen and shifts the curve to the left; pulse oximetry looks normal.
- Severe carbon monoxide poisoning can cause necrosis of the globus pallidus.
- Radon in homes and mines is the second cause of lung cancer after tobacco.
- Occupational cancers: benzene → leukaemia; vinyl chloride → liver angiosarcoma; aromatic amines in dyes → bladder cancer.
Step by step
- Large particles stay in the nose and bronchi; the finest reach the alveoli.
- Alveolar macrophages engulf the particles and release cytokines, free radicals and growth factors.
- Toxic dusts such as silica kill the macrophages, which release them again and keep the cycle going.
- Fibroblasts lay down collagen: nodular or diffuse fibrosis of the lung (pneumoconiosis).
- Fine particles and ozone also act on the blood and vessels: endothelial inflammation, thrombosis and arrhythmia.
Dusts and the lung disease they cause
| Exposure | Lesion | Distinctive feature |
|---|---|---|
| Coal dust | Anthracosis, coal workers' pneumoconiosis, massive fibrosis | Upper lobes; Caplan syndrome with rheumatoid arthritis |
| Silica (quarries, sandblasting, mining) | Silicosis with fibrotic nodules | Upper lobes, eggshell calcification of hilar nodes, higher risk of tuberculosis |
| Asbestos (insulation, shipyards, brakes) | Asbestosis, pleural plaques, mesothelioma, lung cancer | Lower lobes; ferruginous bodies; strong synergy with smoking |
| Beryllium (aerospace, electronics) | Chronic berylliosis | Non-caseating granulomas, like sarcoidosis |
| Organic dusts (mouldy hay, birds) | Hypersensitivity pneumonitis | Immune reaction with poorly formed granulomas |
Test yourself
Think of the answer, then tap the question to see it.
Why does silicosis raise the risk of tuberculosis?
Silica damages alveolar macrophages and their ability to kill mycobacteria.
What is a ferruginous body?
An asbestos fibre coated with iron-protein material, golden-brown and beaded, seen in lungs exposed to asbestos.
Why is pulse oximetry misleading in carbon monoxide poisoning?
The oximeter reads carboxyhaemoglobin almost like oxyhaemoglobin, so saturation looks normal while oxygen delivery is low.
Which occupational dust disease looks like sarcoidosis under the microscope?
Chronic berylliosis, with non-caseating granulomas.
Related
- Tobacco: how smoking injures tissue
- Chemical carcinogens: initiation, promotion and the table to know
- Fibrosis in organs: TGF-β and the myofibroblast
- Granulomatous inflammation: caseating vs non-caseating, the causes to know
- Pigments in tissue: lipofuscin, hemosiderin, melanin, bilirubin, carbon
- Heavy metals: lead, mercury, arsenic and cadmium
Related conditions
- Pneumoconioses (silicosis, asbestosis, coal workers' pneumoconiosis)
- Chronic obstructive pulmonary disease (COPD)
- Carbon monoxide poisoning
- Malignant pleural mesothelioma
- Lung cancer
- Hypersensitivity pneumonitis
- Asthma
- Interstitial lung disease
- Pulmonary tuberculosis
- Bladder cancer
- Acute leukaemia (AML and ALL)
- Cyanide poisoning
Elsewhere in DurgiPedia
- Airway defenses, cough and mucociliary clearance
- Carbon monoxide, methemoglobin and cyanide
- Oxygen transport and the dissociation curve
- The alveolus: type I and II pneumocytes, surfactant, the blood–air barrier
- The airway: from nose to bronchioles
- Monocyte and macrophage
- Type III hypersensitivity (immune complexes)
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Ambient (outdoor) air pollution (World Health Organization, 2026); Household air pollution (World Health Organization, 2026); Carbon monoxide poisoning: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.