An analysis of data from the Negev Migraine Cohort (2000-2023) found that people were 41% more likely to seek emergency care for a migraine on days when airborne nitrogen dioxide levels were highest, and 23% more likely on days when solar radiation was highest. Cumulative exposure to nitrogen dioxide and PM2.5 particles in the air was associated with increased use of anti-migraine triptans. The paper is Neurology.
Migraine is a neurological disorder that causes repeated attacks of moderate to severe headaches. The pain is often throbbing or pulsating, affects one side of the head, and is worse during physical activity. In addition to a headache, a migraine attack typically includes nausea, vomiting, and sensitivity to light, sound, and smell. Some people experience auras before or during a headache, including flashing lights, blind spots, tingling, and difficulty speaking. Attacks can last from several hours to several days and can seriously interfere with daily life.
Migraines can be caused by factors such as stress, lack of sleep, hormonal changes, skipping meals, certain foods, and changes in weather. Acute attacks can be treated with regular painkillers, anti-inflammatories, anti-nausea drugs, or migraine-specific medications called triptans. Triptans, such as sumatriptan, reduce migraine symptoms after an attack has started, but are generally not used as routine preventive medications.
Study author Ido Perez and colleagues wanted to assess the short- and medium-term effects of environmental exposure on migraine activity. The researchers note that while recent studies have demonstrated interactions between long-term exposure to nitrogen dioxide (NO2) and high temperatures, these associations were examined on monthly and annual timescales. These authors proposed a multilayered model of migraine activity that includes acute triggers of migraine attacks, along with biological vulnerabilities and medium-term environmental regulators.
The study assessed the association between ambient air pollution, climate factors, and migraine activity in Beersheba, an Israeli city of approximately 220,000 people located in the arid northern Negev desert. This region is characterized by hot and dry summers, mild winters, and large temperature fluctuations during the day. Air quality is affected by desert dust and urban emissions. In the region, frequent dust storms increase the concentration of particulate matter (PM10 and PM2.5 particles) in the air, and transportation and industry increase nitrogen dioxide and ozone concentrations.
Study data were obtained from adult patients in Beersheba identified from the latest 2023 edition of the Negev Migraine Cohort Study. This is a large, population-based, retrospective study of adults in southern Israel who were identified through medical records with a diagnosis of migraine or prescription of triptans. The study authors combined data on when these people sought emergency care for migraines and their use of the anti-migraine drug triptans with ambient air pollution and weather data from the Department of Environmental Protection’s monitoring network.
Data on exposure to air pollutants were obtained from numerous monitoring stations that measure air concentrations of various pollutants. The pollutants analyzed in this study included nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, PM10 and PM2.5 particles. Tracked weather parameters include relative humidity, temperature, and solar radiation. Measurements were recorded at 5-minute intervals and aggregated as daily averages. The scientists also calculated quarterly exposure values.
In total, the study analyzed data from 7,032 migraine patients living in Beersheba. Approximately 77% of them were women. Their average age was 47 years. The study analyzed data collected between 2000 and 2023.
Results showed that 47% of patients purchased a triptan product at least once during the study period. Among these triptan users, the average triptan use was 2.1 tablets per month, but 9% of them used 5 to 9 tablets per month. Thirty-two percent of patients had at least one migraine-related emergency medical encounter during the study period. Of these, 29% had four or more visits.
The results further showed that a person’s exposure to the highest observed nitrogen dioxide concentration was associated with a 41% higher probability of a migraine-related emergency medical encounter the next day compared to that person’s exposure to the lowest observed concentration. Similarly, the highest observed solar radiation exposure was associated with a 23% higher probability of experiencing a migraine-related medical emergency the next day compared to the lowest observed exposure.
Cumulative exposure to nitrogen dioxide in the previous quarter was associated with a 10% increase in the incidence of triptan drug use, while increased exposure to PM2.5 particles was associated with a 9% increase in the incidence of triptan use.
Weekly weather conditions changed the impact of pollutants. During summer weeks with high temperatures and low humidity, the odds of a medical emergency for nitrogen dioxide-related migraines more than doubled. Similarly, the odds of seeking emergency care for migraines related to exposure to PM2.5 particles increased nearly fourfold during cold, wet winter weeks.
“This study supports a multilayered model of migraine activity in which environmental exposures act as both acute triggers and modulators of brain susceptibility,” the study authors concluded. “Clinically, these results highlight an opportunity for anticipatory prevention, tailoring behavioral strategies, short-term prevention, and acute treatment to the expected period of high-risk exposure.”
This study contributes to the scientific understanding of environmental factors that can cause migraine attacks. However, it should be noted that this study captured migraine activity through emergency medical response and pharmacy data. These metrics primarily capture episodes in which migraine symptoms were most severe. Therefore, findings regarding mild migraine episodes (episodes that individuals can manage on their own without seeking emergency medical help or relying on specialized medications) may differ. Additionally, actual personal exposure may differ from data from surrounding monitoring stations if people stay indoors or use air conditioning on hot or polluted days.
The paper, “Acute environmental triggers and intermediate modulators in emergency migraine-related medical encounters,” was authored by Ido Peles, Lena Novack, Michal Gordon, Batia Sarov, Victor Novack, and Gal Ifergene.
