Personal exposure to polycyclic aromatic compounds and particle size distributions in asphalt paving fume.
Hanley K; Fernback J; Meeker J; McClean M; Herrick R
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :95
Asphalt fume is a complex mixture of aliphatic and aromatic hydrocarbons, cyclic alkanes, and heterocyclic compounds containing S, N, or O. Irritation has been reported and low levels of possible carcinogenic polycyclic aromatic compounds (PAC) are present in asphalt fume. The objective of this study was to measure the particle size of asphalt paving fume to more effectively characterize worker's exposures. Eight area and 8 personal full-shift air samples were collected with impactors and HPLC analysis was used to determine PAC concentrations with cut-points of 10, 3.5, 1, and 0.5 mm. Because of analytical limitations from co-eluting compounds, total PAC was measured with NIOSH method 5800 using 370 and 400 nm emission wavelengths. The 370 nm detector is more sensitive to 2-3 ring PAC; the 400 nm detector is more sensitive to larger PAC, Vapor PAC was sampled with sorbent tubes behind the impactors. Particle size distributions were also screened using an optical particle counter (OPC) and scanning electron microscopy (SEM). Workers' exposure to particulate concentrations ranged from 24-149 and 3.4-29 mg/m3 for PAC370 and PAC400, respectively, suggesting smaller PAC was more abundant. Breathing zone PAC results show that asphalt paving fume is a fine aerosol, with approximately 81-96% being respirable; mass median diameters (MMD) were 0.8-1.2; 0.6-1.0; and 0.6-0.7 um for the paver operator, screed operators, and lutemen (most GSD approximately 2-3). Vapor PAC accounted for 21-41% of the total PAC. The OPC showed that approximately 90% of the fume was detected in particles <3.5 um and confirmed that lower MMDs occurred as the work location was further removed from the paving tractor. SEM analysis revealed the fume to be bimodal with large numbers of particles <0.5 um. This study demonstrates that paving workers are exposed to PAC which penetrates to the alveolar regions.
Exposure-levels; Polycyclic-aromatic-hydrocarbons; Asphalt-fumes; Asphalt-industry; Asphalt-concretes; Aliphatic-compounds; Aromatic-hydrocarbons; Heterocyclic-compounds; Workers; Particulates; Aerosols
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California