Occupational and Environmental Lung Diseases

Asbestosis

Features

•    Chronic fibrosing interstitial lung disease from asbestos fibre inhalation

•    Lower zone predominant fibrosis

•    Long latency period (20–40 years)

Clinical

•    Progressive dyspnoea

•    Dry cough

•    Fine bibasal crackles

•    Clubbing common

Imaging

•    CXR: basal reticulonodular shadowing, pleural plaques

•    HRCT: honeycombing, subpleural fibrosis

Risks

•    Bronchogenic carcinoma (risk amplified by smoking)

•    Mesothelioma (pleural malignancy, independent of smoking)

Pleural Plaques

•    Localised areas of pleural fibrosis with calcifications

•    Marker of prior asbestos exposure

•    Usually asymptomatic and benign

Coal Workers’ Pneumoconiosis (CWP)

Simple CWP

•    Small upper lobe nodules

•    Usually asymptomatic

Progressive Massive Fibrosis (PMF)

•    Confluent upper lobe masses

•    Dyspnoea, pulmonary hypertension

Risk factors

•    Long-term coal dust exposure

•    Often coexists with rheumatoid arthritis (Caplan’s syndrome: large rheumatoid nodules in lungs)

Silicosis

Features

•    Upper lobe predominant nodular fibrosis

•    Occupational exposure: mining, quarrying, sandblasting

Imaging

•    CXR: multiple small nodules, upper zones

•    Eggshell calcification of hilar lymph nodes (classic clue)

Risks

•    Markedly increased risk of TB reactivation

•    Increased risk of lung cancer

Berylliosis

Features

•    Granulomatous lung disease resembling sarcoidosis

•    Exposure: aerospace, electronics, nuclear, fluorescent lamp industries

Clinical

•    Dyspnoea, cough, fatigue

•    Non-caseating granulomas on biopsy

Diagnosis

•    Beryllium lymphocyte proliferation test

Byssinosis

Features

•    Hypersensitivity reaction to cotton dust, textile industry

Clinical

•    "Monday chest tightness" (symptoms worse at start of work week, improve over weekend)

•    Progressive dyspnoea over years

Occupational Asthma

Features

•    Variable airflow obstruction and airway hyperresponsiveness

•    Triggers: flour dust (bakers), isocyanates (spray painters), laboratory animal proteins

Diagnostic clues

•    Improvement on weekends or holidays

•    Peak flow monitoring at work vs home

Management

•    Remove exposure

•    Standard asthma treatment

Reactive Airways Dysfunction Syndrome (RADS)

Features

•    Acute onset asthma-like symptoms following single high-level irritant exposure (e.g., chemical spill)

Distinctive points

•    No latency or sensitisation period

•    May become chronic

Extra Revision Pearls

•    Lower lobe fibrosis → asbestosis, IPF

•    Upper lobe fibrosis → CWP, silicosis, TB, sarcoidosis

•    Asbestosis + smoking → greatly increases lung carcinoma risk (especially squamous cell)

•    Eggshell calcification → classic exam clue for silicosis

•    Caplan’s syndrome → CWP + rheumatoid arthritis nodules

•    Mesothelioma → pleural-based tumour; does not require smoking cofactor

•    RADS → no latency, unlike classic occupational asthma which needs sensitisation