Higher relative humidity and higher ozone might increase the chances of onset of migraine headaches in patients with migraine, according to a study published in Environment International.
From the Boston, Massachusetts area, researchers recruited patients of the current study, which was conducted between March 2016 and October 2017. Eligible participants were 18 years or older, were capable of communicating in English, and had a history of migraine for at least 3 years. Participants filled out both morning and evening diaries to report the occurrence of migraine headache, since their last diary input. Each participant was followed for an average of 45 days.
Weather parameters, comprising ambient temperature, relative humidity, and barometric pressure were obtained from the local weather station. From different sites in the greater Boston area, daily average fine particulate matter, daily maximum 1-hour sulfur dioxide, daily maximum 1-hour nitrogen dioxide, daily maximum 8-hour ozone, and daily maximum 8-hour carbon monoxide were obtained from the US Environment Protection Agency’s Air Quality System. After screening, the data were collected from a total of 98 patients enrolled in the study, who had a mean age of 35 years and were mostly women (88%).
Researchers noted that higher relative humidity was associated with higher odds of migraine headache. However, this association was observed only in the warm weather season (April through September). The results also showed that during the cold weather (October through March) season, higher levels of daily maximum 8-hour ozone and daily maximum 8-hour carbon monoxide seemed to have higher odds of triggering migraine headache. The researchers noted that the associations for ozone and relative humidity were weakened and lost their statistical significance in the overall generalized estimating equation analysis.
Limitations to the study included the small sample size and the low air pollution levels in the local region of the study. For each participant, the variations in the level of exposure were also relatively low during the follow up. The majority of the participants in the study were women of European origin, limiting generalization. Furthermore, weather condition parameters were measured only at 1 weather station, but the air pollution parameters were measured at various stations, which could have caused errors.
Although study researchers suggested the possible correlation between migraine headache onset and the weather and environmental factors, they said that future larger-scale studies with headache diaries and longer follow-up periods are needed to support or challenge the findings of the current study.
Disclosures: One study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Li W, Bertisch S, Mostofsky E, Buettner C, Mittleman M. Weather, ambient air pollution, and risk of migraine headache onset among patients with migraine [published online August 22, 2019]. Environ Int. doi: 10.1016/j.envint.2019.105100