Migraine and air pollution: A systematic review

Area of Science:

• Environmental Health
• Neurology
• Epidemiology

Background:

• Air pollution is a widespread environmental exposure.
• Emerging evidence suggests a potential link between air pollutants and migraine triggers.
• No prior systematic review has comprehensively assessed this association.

Purpose of the Study:

• To systematically synthesize existing evidence on the relationship between ambient air pollution and migraine.
• To evaluate the strength and consistency of associations across various pollutants and migraine outcomes.

Main Methods:

• Conducted a systematic search for empirical studies quantifying outdoor air pollution and migraine outcomes.
• Included short-term and long-term exposure studies, excluding indoor pollution, perfumes, or tobacco smoke.
• Assessed risk of bias using the WHO bias assessment instrument for air quality guidelines.

Main Results:

• Included 12 studies with over 4 million participants, using designs like case-crossover and time series.
• Carbon monoxide, nitrogen dioxide, ozone, and PM2.5 showed higher percentages of point estimates above 1.00, indicating increased risk.
• Nitrogen dioxide associations were most consistent, though confidence intervals often included the null value.

Conclusions:

• A notable association exists between common air pollutants (CO, NO2, O3, PM) and migraine.
• Nitrogen dioxide demonstrated the most consistent link with migraine risk.
• While methodologies were generally strong, the limited number of studies warrants cautious interpretation.