Abstract Introduction Occupational asthma is the most common preventable occupational lung disease and contributes to up to 15% of adult-onset asthma cases (Tarlo, NEJM 2014). Diagnosis is frequently delayed due to overlap with severe or brittle asthma, leading to inappropriate treatment escalation and prolonged corticosteroid exposure (Gibson, Respirology 2015). Removal from the triggering workplace exposure can lead to rapid improvement in symptoms and lung function (Beach, Evid Rep Technol Assess 2025). We present a case of presumed steroid-dependent brittle asthma demonstrating near-complete lung function recovery after temporary removal from welding exposure. Case A 48-year-old man was seen in the Asthma Clinic for ongoing management of presumed brittle asthma. He was using high-dose Trimbow (inhaled corticosteroid/long-acting beta-agonist/long-acting muscarinic antagonist) twice daily and daily theophylline. He had been diagnosed in 2021 following hospitalisation due to a viral exacerbation. He denied childhood respiratory illnesses and had no family history of asthma. Past medical history included hypertension and dyslipidaemia. He was an ex-smoker (15 pack-years) and had worked as a welder since age 18.Over the next four years, he experienced frequent exacerbations requiring repeated oral corticosteroids and stepwise pharmacologic escalation. Due to cumulative steroid use, trimethoprim-sulfamethoxazole prophylaxis was commenced. Despite maximal inhaled therapy, he continued to have exertional dyspnoea and chronic cough. Fractional exhaled nitric oxide (FeNO) remained 20 ppb, suggesting that airway inflammation was less likely. Spirometry performed four months prior showed severe airflow obstruction with an FEV₁ 0.84 L (Z-score:-5.6) and FEV1/VC of 44% (Z-score:-4.8).At routine follow-up, spirometry unexpectedly demonstrated a dramatic improvement with a FEV₁ 4.07 L (Z-score:-0.8) and FEV1/VC of 66% (Z-score:-1.7). The patient also reported marked symptomatic improvement. The only change since his previous assessment was taking extended leave from work due to a shoulder injury. Detailed exposure history revealed daily welding with intermittent fume protection. The diagnosis was revised to occupational asthma. He remains asymptomatic while away from work, and supporting documentation was provided for a workers’ compensation claim. Discussion This case illustrates how occupational asthma can mimic brittle asthma and lead to unnecessary escalation, including biologics and chronic steroids (GINA 2024). The 3 L improvement in FEV₁ following cessation of welding exposure is highly unusual and highlights the reversibility of occupational asthma when exposure is eliminated. Early recognition via detailed occupational history-taking is crucial. In adult-onset asthma, particularly with persistently low FeNO and poor response to corticosteroids, occupational asthma must be actively considered. This abstract is funded by: None
Abdul et al. (2026) studied this question.