Exposure to sun and nitrogen dioxide may increase the likelihood of migraine

An analysis of data from the Negev Migraine Cohort (2000-2023) found that people had 41% higher odds of seeking emergency medical help for migraine on days following the highest concentration of nitrogen dioxide in the air, and 23% higher odds on days following the highest solar radiation. Cumulative exposure to nitrogen dioxide and PM_2.5 particles in the air was associated with increased use of the anti-migraine drug triptan. The paper was published in Neurology.

Migraine is a neurological disorder that causes recurrent attacks of moderate to severe headaches. The pain is often throbbing or pulsating, affects one side of the head, and becomes worse during physical activity. Aside from headaches, migraine attacks commonly include nausea, vomiting, and increased sensitivity to light, sounds, or smells. Some people experience an aura before or during the headache, which may involve flashing lights, blind spots, tingling, or difficulty speaking. An attack can last from several hours to several days and may seriously interfere with everyday activities.

Migraine can be triggered by factors such as stress, lack of sleep, hormonal changes, skipped meals, certain foods, or changes in the weather. Acute attacks may be treated with ordinary painkillers, anti-inflammatory medicines, anti-nausea drugs, or migraine-specific medicines called triptans. Triptans, such as sumatriptan, reduce migraine symptoms after an attack has begun but are not generally used as daily preventive medicines.

Study author Ido Peles and colleagues wanted to assess the short-term and intermediate-term effects of environmental exposures on migraine activity. They note that recent work demonstrated interactions between long-term exposure to nitrogen dioxide (NO₂) and high temperature, but that these associations were examined at monthly and yearly time scales. These authors proposed a layered model of migraine activity that includes acute triggers of migraine attacks along with biological vulnerabilities and intermediate-term environmental modulators.

In this study, they evaluated the associations between ambient air pollution, climatic factors, and migraine activity in Be’er Sheva, an Israeli city of around 220,000 residents located in the arid northern Negev desert. This area is characterized by hot, dry summers, mild winters, and wide temperature variations during the day. Air quality is influenced by desert dust and urban emissions. In this area, frequent dust storms increase concentrations of particulate matter in the air (PM₁₀ and PM_2.5 particles), while traffic and industries contribute to nitrogen dioxide and ozone concentrations.

Free daily newsletter

Study data came from adult patients residing in Be’er Sheva who were identified from the updated 2023 version of the Negev Migraine Cohort study. This is a large, population-based retrospective study of adults in southern Israel, identified through medical records by migraine diagnoses or triptan prescriptions. The study authors integrated data on when these people sought emergency medical help for migraine and their use of the anti-migraine drug triptan with ambient air pollution and meteorological data obtained from the Ministry of Environmental Protection monitoring network.

Data on exposure to air pollutants came from a number of monitoring stations that measured air concentrations of various pollutants. Pollutants analyzed in this study included nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, PM₁₀ and PM_2.5 particles. Meteorological parameters tracked included relative humidity, temperature, and solar radiation. Measurements were recorded at 5-minute intervals and aggregated into daily averages. The scientists also calculated quarterly exposure values.

In total, the study analyzed data from 7,032 patients with migraine residing in Be’er Sheva. About 77% of them were women. Their average age was 47 years. The study analyzed data collected between 2000 and 2023.

Results showed that, during the study period, 47% of patients purchased triptan medication at least once. Among these triptan users, the average triptan use was 2.1 tablets per month, but 9% of them used between 5 and 9 tablets per month. Thirty-two percent of patients had at least one emergency migraine-related healthcare encounter during the study period. Among these individuals, 29% had 4 or more visits.

Results further showed that exposure to a person’s maximum observed nitrogen dioxide concentration was associated with 41% higher odds of an emergency migraine-related healthcare encounter the following day, compared with exposure to that person’s minimum observed concentration. Maximum observed solar radiation exposure was similarly associated with 23% higher odds of an emergency migraine-related healthcare encounter the following day, compared with minimum observed exposure.

Cumulative exposure to nitrogen dioxide during the previous quarter was associated with a 10% higher incidence of triptan medication use, while increased exposure to PM_2.5 particles was associated with a 9% higher incidence of triptan use.

Weekly climatic conditions modified the effects of pollutants. During summer weeks when temperatures were high and humidity was low, the nitrogen dioxide-related odds of seeking emergency medical help for a migraine were more than doubled. Similarly, the odds of seeking emergency medical help for a migraine associated with exposure to PM_2.5 particles were increased almost 4 times during cold and humid winter weeks.

“This study supports a layered model of migraine activity in which environmental exposures act both as acute triggers and as modulators of brain susceptibility,” the study authors concluded. “Clinically, these results highlight opportunities for anticipatory prevention; aligning behavioral strategies, short-term prophylaxis, and acute treatment with forecasted high-risk exposure periods.”

The study contributes to the scientific understanding of environmental factors that may trigger migraine attacks. However, it should be noted that the study captured migraine activity through emergency health care encounters and pharmacy data. These indicators primarily capture episodes in which migraine symptoms were the most severe. Because of this, findings related to milder migraine episodes—episodes that individuals are able to manage themselves without seeking emergency medical help or relying on specialized medication—may differ. Additionally, actual individual exposure may differ from ambient monitoring station data if people stayed indoors or used air conditioning on hot or polluted days.

The paper “Acute Environmental Triggers and Intermediate-Term Modulators of Emergency Migraine-Related Health Care Encounters” was authored by Ido Peles, Lena Novack, Michal Gordon, Batia Sarov, Victor Novack, and Gal Ifergane.