Ryan F. Hoy

Background: Bushfires (also known as wildland or forest fires) expose emergency responders to occupational hazards under exceptional circumstances. Whilst the health impacts of structural firefighting have been studied, less is known about the non-respiratory health impacts or risk of mortality amongst bush firefighters, who can be volunteers. More information about health risks is needed to generate effective prevention strategies. Objective: To critically evaluate and synthesise the published evidence about the non-respiratory health risks and risk of mortality associated with bushfire fighting. Methods: A systematic literature search was conducted in Medline, Scopus, and Embase to identify studies evaluating morbidity or mortality or associated risk factors among bushfire fighters. The quality of included studies was evaluated twice independently using a specific quality assessment tool. Results: Twenty-seven studies were included. 11(41%) were assessed as moderate quality and 16(59%) as low quality. There is a growing body of evidence for adverse short-term impacts of bushfire fighting on mental health and injuries. Linkage studies showed that volunteer firefighters had lower mortality and cancer risk in their late forties compared to the general population. Conclusions: Most studies relied on cross-sectional and retrospective designs without comparison groups, limiting the ability to draw robust conclusions. It is essential to conduct higher-quality research using prospective designs and longer-term follow-up to better understand the health outcomes of bushfire fighting, particularly given the anticipated increase in the frequency and severity of bushfires.

Objective: Compared with silicosis, there has been less research on other respiratory diseases in stone benchtop industry workers. Therefore, we explored respiratory symptoms, airflow obstruction and asthma, including associations with workplace dust exposure, in these workers. Methods: This study included voluntary participants from a stone benchtop industry screening programme conducted in Victoria, Australia, which included chest X-rays, respiratory function tests and a respiratory symptom questionnaire. Asthma status was determined based on self-report, and respiratory function tests were used to measure airflow obstruction. The associations between workplace dust exposure and respiratory symptoms were compared using logistic regression, adjusting for age, smoking status and silicosis. Results: The prevalence of self-reported asthma in this cohort was 20% (90/450 workers). Workers with histories of high workplace dust exposure, even those without silicosis, were more likely to have self-reported asthma and to report respiratory symptoms. Those with obstruction but no bronchodilator response on respiratory function tests were more likely to report histories of high workplace dust exposure. For over half of workers with wheeze or difficulty breathing, symptoms improved at weekends and/or on holidays. Conclusions: There was a high prevalence of self-reported asthma in stone benchtop industry workers and an association between workplace dust exposure and airflow obstruction without bronchodilator response, as well as self-reported asthma, independent of silicosis. These findings suggest a potential role of artificial stone dust exposure in the development of obstructive lung disease, in addition to silicosis.

Extreme bushfires are devastating and costly and are predicted to increase in frequency. This project investigated emergency responders' (ER) compensable injury/disease costs associated with extreme bushfire periods compared with the general workforce. Workers' compensation claims data for Victoria, Australia, were sourced for ER and controls (10% of the general workforce) from January 2005 to April 2021 (encompassing two extreme bushfires). Using generalised linear models, claims from ambulance officers, career firefighters, police, and controls were compared across extreme bushfires, other summers, and all other periods. In total, ER made 749/24,008 (3.1%) claims in extreme bushfire periods, compared to 1254/49,484 (2.5%) in the controls. The study group overall (including both ER and the general workforce control group) experienced significantly higher income compensation costs/claims during extreme bushfire periods, with a 31% increase. ER' costs/claims were highest for mental illness, burns and cancer. After accounting for bushfire impacts on the general workforce, total claims costs were increased by 67% among firefighters in extreme bushfire periods, largely attributable to fatality payments (other non-medical expenses). These results highlight the need for targeted injury prevention for fatal and non-fatal injuries among ERs and measures that address the broader socio-economic impacts on ERs and the general workforce.

Background: Inducible laryngeal obstruction (ILO) is characterised by symptomatic inappropriate adduction of the vocal cords during respiration. There is a spectrum of clinical ILO presentations, and it is unknown whether this heterogeneity reflects pathogenesis or natural history. Objective: We aimed to objectively identify clinically relevant ILO phenotypes. Methods: We included consecutive patients assessed between March 2016 and September 2023 with laryngoscopy evidence of ILO. Patients were analysed using latent class analysis (LCA) by; age, self-reported symptom triggers, and comorbidities. LCA models were assessed by statistical criteria and for clinical plausibility. ILO phenotypes from the selected model were compared by clinical course, laryngoscopy findings, and patient-reported outcomes. Results: LCA of 192 ILO patients identified four phenotypes labelled by predominant clinical characteristics. Isolated ILO (32.8%,n=63), characterised by inhaled and airborne triggers without comorbidities; hyperventilation-associated ILO (41.7%,n=80) characterised by hyperventilation, anxiety, sinonasal disease and triggered by inhaled and airborne exposures; polymorbid ILO (18.2%,n=35) characterised by anxiety, sinonasal disease, lower airway obstruction, obesity and gastroesophageal reflux symptoms; and pseudo allergic ILO (7.3%,n=14) characterised by patient-presumed exposure to an allergen in the absence of specific IgE sensitization. Polymorbid ILO was associated with higher Vocal Cord Dysfunction Questionnaire, higher Chemical Sensory Hyperreactivity and lower Laryngeal Hypersensitivity Questionnaire scores, and expiratory phase-limited ILO (all p<0.01). Pseudo allergic ILO had the shortest duration of illness (p=0.03) and was least likely to respond to laryngeal retraining (p=0.02). Conclusions: Four identified ILO phenotypes with heterogenous and distinct clinical characteristics are further differentiated by clinical course and laryngoscopy providing support for distinct pathogenic pathways in ILO.

Background: The fabrication and installation of artificial (engineered) stone countertops is a relatively new cause of silicosis. Our aim was to investigate silicosis rates in Victoria, Australia, and the association with stone countertop industry work. Methods: Workers' compensation claims for silicosis from January 1, 1991 to December 31, 2022 were analyzed across 8-year time periods. Incidence rates per 100,000 persons were calculated by time period, age, and sex. Additionally, incident silicosis cases were reported to a clinical registry by respiratory physicians from May 1, 2019 to December 31, 2022, and analyzed by referral source and occupational history. Results: Over 32 years, there were 536 workers' compensation claims for silicosis (98.9% male, median age 40 years). In total, 482 (89.9%) were received between 2015 and 2022, a 27-fold increase from the previous 8-year period. The incidence rate for silicosis claims in the adult population increased from 0.12 per 100,000 in 1991-1998 to 2.38 per 100,000 in 2015-2022. In the clinical registry there were 210 incident cases between 2019 and 2022; 97% worked in the countertop industry, 95% with artificial stone. Almost all (89%) cases had been referred following participation in a government screening program for stone countertop industry workers. Conclusions: There has been a major rise in compensation claims for silicosis in Victoria. Active screening of stone countertop workers led to the diagnosis of almost all registered incident silicosis cases. This underscores the risk to stone countertop workers and highlights the potential for under-recognition of silicosis without screening at-risk workers, especially in countries where artificial stone has become popular.