Study Examines Links Between Weather, Pollution, Migraines

A study investigating the effects of weather and air pollution on migraine found that higher relative humidity was associated with higher odds of migraine onset in warm season months.

The research, published by Environment International, used data from electronic questionnaires from 98 adults with episodic migraine in the Boston area between 2016 and 2017. Patients were followed for an average of 45 days while temperature, relative humidity, and barometric pressure data was collected from a local weather station. Air pollution monitors were also used to evaluate the conditions of the air.

“Weather conditions and air pollution levels may be influenced by regional climate and/or pollution sources. Moreover, data from emergency department visits records may be affected by factors that may influence patients' decision to visit the emergency department, such as migraine headache severity, duration, and health care access,” noted the authors. “We therefore conducted a prospective diary-based cohort study to examine the associations of temperature, relative humidity, barometric pressure, and ambient air pollutants with migraine headache onset.”

The results following the observations revealed that the average temperature was 56.9 degrees Fahrenheit, the relative humidity was 67.3%, and the fine particulate matter was 7.3 μg/m³.

Furthermore, the researchers found association between higher relative humidity and higher odds of migraine headache during the warm season—April through September. During the cold season, October through March, higher levels of daily maximum 8-hour ozone and daily maximum 8-hour carbon monoxide appeared to be associated with higher odds of migraine onset.

There seemed to be weak positive associations of higher daily maximum 1-hour nitrogen dioxide, daily maximum 8-hour ozone, and daily maximum 8-hour carbon monoxide with higher odds of migraines in the cold season. Although the associations for ozone and relative humidity weakened and were no longer statistically significant in the final sensitivity analysis, the differing associations by season remained.

“Our findings suggest an association between higher relative humidity and onset of migraine headache, especially in warm season; and higher levels of ambient [ozone] O₃ may be associated with higher risk of having migraine, particularly in cold season,” the authors concluded. “Weak positive associations were also found for other traffic-related air pollutants in cold season. Although the associations for O3 and relative humidity were not observed in the overall GEE analysis, the differing associations by season remained.”

The study suggested that future studies on a larger scale with longer follow-up times are necessary to confirm these findings.

Reference

Li W, Bertisch S, Mostofsky E, et al. Weather, ambient air pollution, and risk of migraine headache onset among patients with migraine [published online August 2019]. Environ Int. doi: 10.1016/j.envint.2019.105100.