Table 1 Case definitions for work-related respiratory disease

Disease	Criteria for case definitions
Extrinsic allergic alveolitis (at least 4 of the 7 criteria must be met)16	Onset of disease after December 2002 and: (1) physician diagnosis of EAA (probable or definite); (2) onset of at least two pulmonary symptoms (cough, wheeze, chest tightness, shortness of breath) and one systemic symptom (fever, weight loss); (3) a history of symptoms improving regularly on days away from work and deteriorating on return to work; (4) Restrictive pattern on spirometry: FVC <80% predicted and FEV₁/FVC >70%; (5) pulmonary carbon monoxide transfer factor <80% predicted; (6) chest radiograph or CT scan showing interstitial, reticulonodular or mosaic pattern; (7) biopsy evidence of non-caseating granulomas and/or lymphocytosis on bronchoalveolar lavage

Occupational asthma	Diagnostic peak expiratory flow record in 2003–5 (ie, OASYS score ⩾2.67 and/or a mean day interpreted difference between work and rest days of ⩾16 l/min)21 22

Humidifier fever	Onset of disease after December 2002 and a physician
	diagnosis based on:
	Recurrent symptoms of a flu-like illness worst on first day of exposure after a break
	No weight loss or radiological infiltrates
	No long-term restrictive lung disease

EAA, extrinsic allergic alveolitis; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity.