TABLE 8.

Impact of confounding variables on the utility of putative biomarkers for diesel exhaust exposure

Category	Atmospheric Aging	Diesel Specificity	Fuel Impacts	Metabolic Half-Life	Regulatory Target	After Treatment Removal	Overall Impact
PAHs	High	Low	Variable	Moderate	Yes	High	High
Oxy-PAHs	Moderate	Low	Variable	Short	Yes	High	High
Nitro-PAHs	Low	Moderate	Variable	Moderate	Yes	High	Moderate
Nanoparticulates	Low	High	Moderate	Long	No	High	Low
Nitropyrene	Low	High	Moderate	Short	Yes	Moderate	Low
Aldehydes	Unknown	Moderate	High	Long (adducts)	No	High	Moderate
Phthalic acid	Low	Moderate	Unknown	Moderate	No	High	Moderate
Carbonyls	High	Moderate	Low	Short	No	High	Moderate
Quinones	Moderate	High	Unknown	Long (adducts)	Yes	High	Low
Dinitropyrenes	Low	Moderate	Moderate	Moderate	Yes	High	Moderate

Bold type highlights those substances that are potentially useful biomarkers of diesel exhaust exposure.