Ambient nitrogen dioxide, temperature exposure, and migraine incidence: A large prospective cohort study.

Objective: This study aimed to quantify the associations of low-level ambient nitrogen dioxide (NO₂) and seasonal temperatures with migraine incidence.

Background: Migraine is a highly disabling neurovascular disorder in which attacks are affected by short-term high-level air pollution; however, the associations of long-term low-level air pollution and climate change on migraine incidence are unknown.

Methods: In this prospective cohort study using data from the UK Biobank, 407,792 participants without migraine at baseline were included. Environmental exposures were assessed monthly and yearly using zip code-linked gridded data. We compared migraine incidence across populations with varying exposure levels of NO₂, seasonal temperatures, and temperature variability to assess their associations with migraine risk.

Results: During a median follow-up of 11.8 years (2316 migraine cases), migraine risk increased with higher NO₂ exposure (adjusted hazard ratio [aHR], 1.10 per 10 μg/m³ increase; 95% confidence intervals [CI], 1.01-1.19), lower winter temperatures (aHR, 1.46 per 5°C decrease; 95% CI, 1.26-1.69), and higher temperature variability in both summer (aHR, 1.19 per 1°C increase; 95% CI, 1.07-1.32) and winter (aHR, 1.07 per 1°C increase; 95% CI, 1.01-1.13). Joint effects were observed between NO₂ and temperature patterns, with the highest risks associated with combinations of high NO₂-low winter temperature (aHR, 1.67; 95% CI, 1.42-1.95), high NO₂-high summer temperature variability (aHR, 1.48; 95% CI, 1.25-1.76), and high NO₂-low winter temperature variability (aHR, 1.64; 95% CI, 1.39-1.93).

Conclusions: The findings that NO₂ and temperature are associated with migraine incidence suggest that to mitigate further the environmental risk factors associated with migraine incidence, we may need to adopt a combination of public health measures of air quality management and climate change adaptation.