A study of interferences in ambient ozone monitors

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:617769

Kleindienst, T E; McIver, C D ^[1]; Ollison, W M ^[2]

---

1. ManTech Environmental Technology, Inc., Research Triangle Park, NC (United States)
2. American Petroleum Institute, Washington, DC (United States)

Recently proposed EPA revisions to the ozone ambient air quality standards change allowable ozone levels from 120 ppbv (1-hour average) to 70-90 ppbv (8-hour average). Accordingly, the relative importance of potential interferences in currently deployed ethylene-chemiluminescence and ultraviolet (UV) absorption monitors may be increased. UV absorption monitors predominate US monitoring networks and operate in a dual channel mode, requiring a scrubber to selectively remove ozone from other UV absorbing species. However, these scrubbers may also remove aromatic species with UV absorption coefficients at 254 run comparable to ozone that could constitute potential interferants. The interference potential for only a few of these compounds has been determined. Additional representative organic precursor species likely to be present under polluted conditions (e.g., C{sub 8}-C{sub 9} aromatic hydrocarbons and their nitroaromatic and phenolic derivatives) have been tested as UV interferants in this study. The removal and reentrainment of aromatic pollutants on ozone scrubbers used in UV monitors is highly dependent on the relative humidity in the system. Raising the temperature of the scrubber does not improve its interferant transmission under dry conditions and increases the retention of potential interferants under humid conditions. Reduced sulfur compounds such as CS{sub 2} do not appear to be interferants for the chemiluminescence monitor.

• OSTI ID: 617769
• Report Number(s): CONF-9704195--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
ABSORPTION
AIR QUALITY
CHEMILUMINESCENCE
HUMIDITY
MONITORS
OZONE