Fig. 1From: Air pollution, methane super-emitters, and oil and gas wells in Northern California: the relationship with migraine headache prevalence and exacerbationDistribution of environmental exposures within study region. Block group level 2015 annual average concentration of a. PM2.5 and b. NO2. c. Methane emission rate based on the California Methane Survey, conducted between 2016 and 2018. D. Location of active oil and gas wells as of December 2015Back to article page