THE PHYSICAL-CHEMICAL CHARACTERISTICS OF PARTICLES ASSOCIATED WITH POLYNUCLEAR AROMATIC HYDROCARBONS PRESENT IN AUTOMOBILE EXHAUST to COORDINATING RESEARCH COUNCIL (APRAC-CAPE-12-68-Neg. 59)
"INTRODUCTION Polynuclear aromatic hydrocarbons (PNA) are generated by the high-temperature pyrolysis of a wide variety of organic substances including gasoline as it is burned by spark-ignition engines. Some PNA compounds have been identified by medical investigators as carcinogens@ and because of the presence of PNA among atmospheric pollutants@ researchers in the health sciences have placed much emphasis on the selective and sensitive detection of specific PNA compounds in samples collected from the air . Recently there has been added concern about the increased carcinogenic activity of PNA associated with inorganic particles residing in the lungs. Although there is a scarcity of data presently available concerning this possible synergistic relationship@ it has become important to learn whether PNA as emitted by the engine exhaust is a s sociated with certain particle types or whether there are no selective associations. Knowledge of any selective association of PNA with distinct particle types also may permit improved control of conditions of emission to eliminate automotive exhaust PNA as atmospheric pollutants. The program efforts described in this report have been directed toward the definition of PNA-particle type relationships. The objective of this CAPE-l2-68-Neg. 59 task@ according to the Work Statement is to ""Investigate the Nature of the Physical-Chemical Characteristics of Particles Associated With Polynuclear Aromatic Hydrocarbons Present in Automobile Exhaust From the Combustion of a Variety of Fuels"". In order to work at this objective within the project funds available@ a decision was made by agreement with the Sponsor to modify the initial proposal somewhat by: (1) simplifying the engine operation@ (2) emphasizing the detection of BaP over other polynuclear aromatic hydrocarbons@ and (3) using a single fuel selected on the basis of high aromatic content. Work has proceeded according to the above definition of activity@ and progress has been made toward: (1) Collection of particulate matter from exhaust gas in a manner which permits segregation of individual particles and/or aggregates. (2) Examination of individual particles and/or aggregates so as to describe differences in physical characteristics. (3) Examination of individual particles and/or aggregates so as to describe differences-in chemical characteristics."