Application of Ultraviolet Spectrophotometry to Estimate Occupational Exposure to Airborne Polyaromatic Compounds in Asphalt Pavers

Abstract

An ultraviolet (UV) spectrophotometric procedure was devised for the determination of polycyclic aromatic compound-oriented organic soluble matter in vapors and particulate collected from emissions of hot asphalt mix. Ultrasonic extraction was carried out with acetonitrile, followed by UV measurements at 254 nm. Polycyclic aromatic compounds (PACs) in volatile and particulate fraction were quantified as phenanthrene or benzo[k]fluoranthene equivalents. A comparison between UV and high-pressure liquid chromatography with fluorescence detection showed that PACs were one to three orders of magnitude higher than the sum of 15 priority polycyclic aromatic hydrocarbons (PAHs); still, significant correlations were found between volatile or particulate PACs and, respectively, total volatile or particulate PAHs. Moreover, in the particulate phase, PACs correlated with total particulate matter quantified by gravimetry. The proposed procedure was employed in a field study for monitoring personal exposure to asphalt emissions of workers engaged in road construction. Observed levels of acetonitrile-soluble PACs in air samples were very low (2–20 μg/m ³ ); however, asphalt pavers were exposed to significantly higher concentrations of volatile PACs than construction workers (geometric mean, 5.9 μg/m ³ vs. 4.1 μg/m ³ ). This method for estimating the global content of volatile or particulate PACs in air samples satisfies our requirements of simplicity and is suitable for conducting an initial screening to assess exposure to airborne polyaromatic organics in asphalt pavers.

Keywords:

• asphalt
• bitumen
• occupational exposure
• organic soluble matter
• polycyclic aromatic compounds
• UV spectrophotometry