Background/Objectives: Air pollution is a major environmental determinant of asthma morbidity and lung function impairment across the life course. Both outdoor and indoor exposures contribute to asthma development and exacerbations, impaired lung function growth, and accelerated decline, with heightened susceptibility during pregnancy and childhood. In this narrative review, we aimed to: (i) synthesize evidence on outdoor and indoor air pollution in asthma and lung function decline; (ii) describe key modulators of pollution-related risk; (iii) evaluate diet and supplementation as effect modifiers; and (iv) outline strategies and recommendations to mitigate pollution-related asthma burden. Methods: A narrative synthesis was conducted based on a comprehensive PubMed literature search through 2025, integrating evidence from observational and interventional studies evaluating habitual diet and nutritional supplementation as potential modifiers of the respiratory effects of indoor and outdoor air pollution. Results: We synthesized human observational and interventional studies associating outdoor and indoor air pollution with asthma and lung function outcomes, highlighted major susceptibility modulators and mechanistic pathways, and appraised emerging evidence that habitual diet and nutritional supplementation might modify pollutant-related respiratory effects. Mechanistic evidence supported dietary modulation through redox buffering, epithelial-immune pathways, lipid-mediated inflammatory balance, and microbiome-immune crosstalk. However, human evidence remained heterogeneous across pollutants, settings, dietary metrics, and endpoints. Conclusions: Emissions reduction at source remained the cornerstone of prevention. Effective mitigation should be multi-level and equity-focused, combining structural air-quality improvements with pollution-aware asthma care and feasible household practices. Diet should be framed as a supportive, food-first resilience strategy, improving overall diet quality, fat quality, and fiber intake rather than a substitute for emissions reduction or guideline-based asthma management.
Carvalho et al. (Sun,) studied this question.