Migraines, characterized by recurrent headaches, are among the most common childhood headaches. Furthermore, childhood migraine may persist into adulthood. The influence of environmental factors on the attacks of migraine/recurrent headaches leads to extensive debate over the past decades. Indeed, environmental factors, such as air pollutants and weather, may produce neurogenic inflammation and trigger migraine/recurrent headaches onset. To date, several studies have suggested an association between some outdoor air pollutants and frequency, severity, or medical consultation rates for headaches. Although studies have suggested environmental factors to be triggers of headache, the contribution of long-term air pollution exposure to recurrent headaches is poorly understood especially in children. Therefore, researchers of China Medical University, Taiwan conducted a nationwide cohort study to investigate associations between levels of ambient air pollutants and risks of recurrent headaches in children in Taiwan from 2000 to 2012.

Researchers used data from the Taiwan National Health Insurance Research Database (NHIRD) and linked them to the Taiwan Air Quality Monitoring Database (TAQMD). They identified 218,008 children aged less than 18 and evaluated them from 1 January 2000, and then followed until they were diagnosed by a physician for ≥3 times with recurrent headaches or until 31 December 2012. They categorized the annual average concentration of each air pollutant (fine particulate matter, total hydrocarbon, methane, sulfur dioxide, and nitrogen dioxide) into quartiles (Q1–Q4).

Key findings of the study were:

•Among 218,008 children, researchers identified 28,037 children (12.9%) with recurrent headaches (≥3 times over median 10.7-year follow-up).

•They noted that most individuals living in areas with higher urbanization levels had higher air pollutant exposure, most likely due to the high vehicle density and population density in urban areas.

•They found that incidence rates for recurrent headaches increased with higher levels of Fine particulate matter (PM2.5), Total hydrocarbons (THC), Methane (CH4), and Nitrogen Oxide (NO2) exposure.

•They also found that the highest incidence rate and the highest adjusted HR (aHR) were in those exposed ≥median temperature and ≥median-level of pollutants.

•They observed the adjusted HR of recurrent headaches development was increased with five air pollutants concentration (PM2.5, THC, CH4, SO2, and NO2). However, they found no association with sulfur dioxide exposure.

•They also didn't found any significant differences between boys and girls in associations.

The authors concluded, "long-term exposure to ambient air pollutants and relatively high ambient temperature are associated with recurrent headaches not only in adults but also in children. With this study, we hope to facilitate the implementation of an appropriate policy of public health for monitoring and further improving air quality—for the health of our children, who are the backbone of the future"

For further information:

https://www.mdpi.com/1660-4601/17/23/9140/htm