Climate-Related PM₂.₅ Exacerbations and Gastroesophageal Reflux Disease in a High-Pollution South Asian Megacity: Implications for Lahore, Pakistan, 1999–2023

Gastroesophageal reflux disease represents a substantial and growing global health burden, with recent Global Burden of Disease estimates indicating over 800 million prevalent cases worldwide and a steady increase in years lived with disability over the past three decades. While GERD and esophagitis are traditionally linked to lifestyle and metabolic risk factors, emerging evidence suggests that environmental exposures—particularly ambient air pollution and climate-related stressors—may contribute to symptom exacerbation and mucosal injury. Long-term exposure to fine particulate matter (PM₂.₅) has been associated with increased GERD incidence and reflux-related healthcare utilization in large population studies, likely mediated through oxidative stress, systemic inflammation, altered esophageal motility, and increased cough-induced reflux events. These associations are particularly relevant for Lahore, Pakistan, which consistently ranks among the most polluted cities globally, with annual PM₂.₅ concentrations over a tenfold higher than World Health Organization (WHO) guidelines and frequent climate-driven smog episodes. Although direct epidemiologic data linking air pollution to esophagitis outcomes in Lahore remain limited, the city’s extreme pollution burden and rising temperatures suggest a plausible and underrecognized contribution to upper gastrointestinal disease risk, highlighting an important gap for future research in South Asia.