Respiratory and Cardiovascular Effects of Traditional versus Electronic Smoking Among Firefighters in Salah ad-Din/Samarra: An Age-Stratified Cross-sectional Study with Hormonal and Immunological Biomarkers

Abstract

Background: Firefighters face dual respiratory challenges from occupational smoke exposure and personal smoking habits. While electronic cigarettes (e-cigarettes) are often perceived as safer alternatives to traditional cigarettes, their cardiovascular and respiratory effects in occupationally exposed populations remain poorly understood.

Objective: To compare pulmonary function, inflammatory/oxidative stress markers, and cardiovascular indicators among traditional cigarette smokers, e-cigarette users, and non-smokers within an age-stratified firefighter cohort.

Methods: This cross-sectional analytical study enrolled 70 firefighters from Salah ad-Din/Samarra Fire Department, age-stratified into four groups (20-29, 30-39, 40-49, 50-59 years). Each age stratum included 5 traditional smokers, 5 e-cigarette users, and 7-8 non-smoking controls. Primary outcomes included spirometry parameters (FEV1, FVC, FEV1/FVC ratio), fractional exhaled nitric oxide (FeNO), high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), malondialdehyde (MDA), and total antioxidant capacity (TAC). Secondary assessments encompassed cardiovascular risk factors, stress hormones, and occupational exposure metrics.

Results: Traditional smokers demonstrated significantly reduced FEV1/FVC ratio (76.2±8.4% vs. 84.1±5.2% in controls, p<0.001) and elevated FeNO levels (42.3±12.7 ppb vs. 18.6±6.4 ppb, p<0.001). E-cigarette users showed intermediate impairment (FEV1/FVC: 80.7±7.1%, FeNO: 28.9±9.2 ppb). Inflammatory markers were highest in traditional smokers (hs-CRP: 4.8±2.1 mg/L vs. 1.2±0.6 mg/L in controls; IL-6: 3.4±1.8 pg/mL vs. 1.1±0.5 pg/mL), with e-cigarette users showing intermediate elevation. Oxidative stress markers followed similar patterns, with traditional smokers exhibiting highest MDA levels and lowest TAC. Age-stratified analysis revealed amplified smoking effects in older firefighters (≥40 years). Conclusions: Traditional cigarette smoking produces more severe respiratory and systemic inflammatory effects than e-cigarette use among firefighters, though both demonstrate significant impairment compared to non-smokers. The interaction between occupational smoke exposure and personal smoking habits suggests cumulative pulmonary damage that accelerates with age. Translational Perspective: These findings support targeted smoking cessation interventions in high-risk occupational populations and inform evidence-based policies regarding alternative tobacco products in safety-critical professions.  Conclusions: Even at an early stage of DN, T2DM patients show a pronounced pro-oxidant shift that parallels renal impairment. OS monitoring may help identify high-risk individuals, while intensified glycaemic control and antioxidant support could attenuate renal damage. Prospective studies should validate these findings and assess antioxidant-based interventions