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

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

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.

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.

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).

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.