Welding fumes and COVID-19 – a dangerous liaison

<bold>Background:</bold> Welding fume exposure may induce small airway inflammation, leading to small airway dysfunction (SAD). SAD has also been identified following COVID-19. We hypothesize that SAD following COVID-19 is more pronounced in individuals exposed to welding fumes due to an already ongoing small airway inflammation. <bold>Methods:</bold> We examined 43 individuals, aged 19 to 62 yrs, exposed to welding fumes (14 with previous COVID-19) and 64 unexposed individuals, aged 21 to 63 yrs, (41 with previous COVID-19). None required hospitalization in the acute phase of COVID-19. Median weeks from infection to inclusion were 91 (exposed) and 65 (unexposed). Spirometry (FEF75), impulse oscillometry (R5, R5-R20 and AX), and multiple breath washout (Scond and Sacin) assessed SAD. Multiple linear regression models explored the impact of exposures (including welding fumes, smoking, and COVID-19, along with the interaction between welding fumes and COVID-19) on lung function. Lung function was expressed with z-scores and exposures were dichotomized (yes/no). <bold>Results:</bold> 59% of exposed and 22% of unexposed were ever smokers, p<0.05. Significant models were found for R5-R20 and Scond, Table 1. Table 1. Results from multiple linear regression models. <table-wrap><object-id>erj;64/suppl_68/PA2221/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td>Adjusted R²</td><td>p-value</td><td>Independent variable</td><td>Unstandardized beta</td><td>p-value</td></tr><tr><td>R5-R20 (z-score)</td><td>0.09</td><td><0.01</td><td>welding fume</td><td>0.87</td><td><0.01</td></tr><tr><td></td><td></td><td></td><td>COVID-19</td><td>0.35</td><td>ns</td></tr><tr><td></td><td></td><td></td><td>ever smoker</td><td>0.22</td><td>ns</td></tr><tr><td>Scond (z-score)</td><td>0.20</td><td><0.001</td><td>welding fume</td><td>-0.60</td><td>ns</td></tr><tr><td></td><td></td><td></td><td>COVID-19</td><td>-0.30</td><td>ns</td></tr><tr><td></td><td></td><td></td><td>ever smoker</td><td>1.76</td><td><0.001</td></tr><tr><td></td><td></td><td></td><td>interaction welding fume and COVID-19</td><td>3.14</td><td><0.01</td></tr></tbody></table></table-wrap> Footnote: R5-R20, resistance at 5 - 20 Hz. ns, non-significant. <bold>Conclusion:</bold> The combination of welding fume exposure and COVID-19 may exacerbate SAD, as assessed by Scond, in the aftermath of infection.