ASPHALT HOT-MIX EMISSION STUDY

The findings of this study may be summarized by the statement that there is no serious air pollution or employee health problem resulting from the use of petroleum-derived asphalt in hot-mixes. The findings are based on eight complete sets of emission samples taken at two hot-mix plants involving four asphalts from three refineries. The emission samples were taken following the discharge of the mix from the mixing chamber. In most of the samplings the immediate area was shrouded to concentrate the emissions, to exclude extraneous matter and to provide more uniform sampling conditions. Most of the air contaminants found in the emissions were at extremely low concentrations and all fell well within currently applicable limits established by the Occupational Safety and Health Administration (OSHA). Analysis of gaseous substances included carbon monoxide, nitrogen dioxide, sulfur dioxide, hydrogen sulfide, carbonyl sulfide, mercaptans, ozone, aldehydes, phenols and C2 to C14 hydrocarbons. Solid particulates were also collected and found to contain only trace amounts of polynuclear aromatic hydrocarbons and metal compunds, much lower than are typically found in emissions from other industrial and commercial sources. The Threshold Limit Value (TLV) for asphalt (petroleum) fumes of 5.0 mg/m to the 3th power, recommended by the American Conference of Governmental Industrial Hygienists (ACGIH) was also considered and found to be slightly exceeded in one sampling. However, each sampling was found to be well within this limit on a time weighted basis (and sampling was made under exaggerated conditions not typical of a workman's exposure). Furthermore, this TLV limit is intended primarily to apply to substances high in polynuclear aromatics, whereas it has been shown that asphalt fumes contain extremely low concentrations of these compounds and are largely made up of innocuous saturated type hydrocarbons. Under the shrouded, concentrated sampling conditions, the amount of vilatile organic hydrocarbons occasionally exceeded the 0.24 ppm limit set forth in the Ambient Air Quality Standards promulgated by the Environmental Protection Agency (EPA). However, it is inconceivable that this limit would ever be reached at the "fence line" of a hot-mix asphalt plant. The same applies to other compounds to be air contaminants.

  • Corporate Authors:

    Asphalt Institute

    2696 Research Park Drive
    Lexington, KY  United States  40511-8480
  • Publication Date: 1975-3

Media Info

  • Features: Figures; Tables;
  • Pagination: 103 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00096711
  • Record Type: Publication
  • Report/Paper Numbers: Rept. No. 75-1
  • Files: TRIS
  • Created Date: Jul 15 1975 12:00AM