Many factors in our environment can trigger Migraines and headaches. Those include fluorescent or flickering lighting, hot or stuffy rooms, perfumes and fragrances, and more. Some of these potential triggers are avoidable; others aren't.
In a recent study, researchers took a look at a potential trigger that's virtually possible to avoid -- air pollution.
"The objective of this systematic review is to evaluate the association between common outdoor air pollutants and headache."
"Patients with recurrent benign headache disorders such as Migraine often report that environmental factors aggravate or cause headache. Air pollutants might serve as low level environmental irritants of structures innervated by the trigeminal nerve or trigger headache through other mechanisms. We conducted a systematic review to evaluate the strength and consistency of evidence supporting a link between direct or indirect measures of headache severity or frequency and levels of the 6 criteria outdoor air pollutants routinely monitored in many developed countries: lead, carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter less than 10 microns (PM10), particulate matter less than 2.5 microns (PM2.5) and sulfur dioxide (SO2.)"
- Researchers searched Medline and Embase through January 10, 2010 for relevant studies.
- Two reviewers independently extracted data, rated study quality and resolved differences by consensus.
- Researchers pulled data about study design and analysis, location or population investigated, time period, contextual factors and whether they were included in the analysis, and assessment of potential confounders such as heat, humidity or the effects of co-pollutants. The methodological quality of the included studies was assessed using published criteria.
- Researchers found 11 studies that met criteria for inclusion in their review.
- Two studies used Migraine and headache diaries to track headache incidence, duration, and severity.
- Two studies looked at changes in house calls due to Migraine and headache.
- Six studies examined changes in emergency room visits for Migraine and headache.
- One study looked at changes in hospital admissions for Migraine and headache.
- No studies examined the association between outdoor air levels of lead and Migraine and headache headache, but all other pollutants were examined in at least four studies.
- Positive associations for all five pollutants were noted in some studies.
- Overall the most consistent associations were seen for NO2 and particulate matter and this remained true when lower quality studies were excluded.
"Available evidence supports the idea of a positive association between levels of some outdoor air pollutants and increased severity, frequency or medical consultation rates for headache and Migraine. These effects occur across the spectrum of headache severity, ranging from increased frequency or duration of headaches that do not prompt medical consultation to an increase in the occurrence of more severe headaches that result in ED (emergency department) visits and even hospitalization. This suggests that pollutants are environmental irritants that right-shift the severity curve in the headache-susceptible population. Although effect sizes are small, headache is a highly prevalent condition and the public health impact of air pollution may be important."
Summary and comments:
This study shows a correlation between Migraines, headaches, and air pollution. Besides social activism to work toward cleaner air, Migraine and headache sufferers who find that pollution impacts them may want to try to stay indoors when possible on days when air pollution is higher. A good filter on heating and air conditioning systems and keeping windows closed when air pollution is high may also help.
Loder E.W.; Cardona L.; Rizzoli P. "Outdoor Air Quality and Headache: A Systematic Review." Research poster presentation. 52nd annual scientific meeting of the American Headache Society. Los Angeles. June, 2010.
Medical review by John Claude Krusz, PhD, MD