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To the Editor: In their Editorial, Drs Thurston and Bates¹ stated "there is no reason to doubt that ozone exposure is a cause of asthma exacerbations." Although Thurston and Bates cited several studies in support of this proposition, none of these measured or controlled for carbon monoxide levels. Studies that have assessed both carbon monoxide and ozone (full list of references available from author) found that ozone was either negatively or not associated with asthma indicators, while increases in average outdoor carbon monoxide levels of just 1 to 2 ppm were more positively associated than any other pollutant or particulates.² Asthma hospitalizations and ambient carbon monoxide concentrations also are highest in fall when ozone levels are lowest and lowest in summer when ozone levels are highest.³

Moreover, carbon monoxide is directly associated with the etiology of asthma as a potent vasodilator and sensory neurotransmitter. Endogenous carbon monoxide produced in lung . . . [Full Text of this Article]

Albert Donnay, MHS
Donnay Environmental Health Engineering
Baltimore, Md