 the 1990 clean air act mandated oxygenation of gasoline in regions where carbon monoxide standards were not met . to achieve this standard , methyl tertiary butyl ether ( mtbe ) 
 was increased to 15% by volume during winter months in many locations . 
 subsequent to the increase of mtbe in gasoline , commuters reported increases in symptoms such as headache , nausea , and eye , nose , and throat irritation . 
 the present study compared 12 individuals selected based on self - report of symptoms ( self - reported sensitives ; srss ) associated with mtbe to 19 controls without self - reported sensitivities . in a double - blind , repeated measures , controlled exposure , subjects were exposed for 15 min to clean air , gasoline , gasoline with 11% mtbe , and gasoline with 15% mtbe . 
 symptoms , odor ratings , neurobehavioral performance on a task of driving simulation , and psychophysiologic responses ( heart and respiration rate , end - tidal co(2 ) , finger pulse volume , electromyograph , finger temperature ) were measured before , during , and immediately after exposure . 
 relative to controls , srss reported significantly more total symptoms when exposed to gasoline with 15% mtbe than when exposed to gasoline with 11% mtbe or to clean air . 
 however , these differences in symptoms were not accompanied by significant differences in neurobehavioral performance or psychophysiologic responses . 
 no significant differences in symptoms or neurobehavioral or psychophysiologic responses were observed when exposure to gasoline with 11% mtbe was compared to clean air or to gasoline . 
 thus , the present study , although showing increased total symptoms among srss when exposed to gasoline with 15% mtbe , did not support a dose - response relationship for mtbe exposure nor the symptom specificity associated with mtbe in epidemiologic studies.imagesfigure 1figure 2 
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