Emission Standards for Particulates

Promulgation of standards of performance under Section 111 and national emission standards for hazardous pollutants under Section 112 of the Clean Air Act is the responsibility of the Emission Standards and Engineering Division of EPA. The problems encountered and the bases used are examined.     

Roadside Coniferous Windbreaks as Sinks For Vehicular Lead Emissions

The role of a roadside windbreak of white pine trees in modifying the dispersion of vehicular lead emissions was evaluated. The lead content of foliage and twigs of various ages adjacent to and far from the road was analyzed by atomic absorption spectrophotometry. The lead burden of older needles and twigs was consistently greater than that of younger organs, and was greater in samples taken adjacent to than far from the road. The pattern of lead accumulation on mature needles, but not twigs, varied with precipitation prior to sampling. Twigs retained particles more effectively than needles throughout the season; twigs retained about 115% more lead as µg g^-1 and about 2050% more lead as µg cm^-2 than similarly located needles. The lead content of soil beneath the windbreak was compared with that of an adjacent, undisturbed field to assess whether the presence Of the windbreak resulted in lead enrichment of the underlying soil. The soil between the curb and the windbreak contained about 50% more lead than that of the field at a similar distance from the road. Within the windbreak, the soil contained about twice the lead content of the soil in the open field at a similar distance from the curb. Windbreaks function as sinks for vehicular lead emissions and thus decrease their dispersion from roads.     

Progress Toward a Uniform Air Pollution Index

Recently, various authors^1–4 have indicated that a need exists to establish a uniform air pollution index for communities throughout the nation.Although the literature reveals several attempts to develop air pollution indices,^5–7 none of these indices has received widespread acceptance by state and local air pollution control agencies, probably because none has received the active support or endorsement of the federal government. We now wish to report that significant progress has been made at the federal level toward the goal of a recommended national air pollution index.     

1987 APCA Govermenet Agencies Directory

A method for setting air quality standards for long-term cumulative exposures of a population based on epidemiological studies has been developed. It uses exposure estimates interpolated from monitoring stations to zip code centroids, each month applied to zip code by month residence histories of the population. Two alternative cumulative exposure indices are used—hours in excess of a threshold, and the sum of concentrations above a threshold. The indices are then used with multiple logistic regression models for the health outcome data to form dose response curves for relative risk, adjusting for covariates. These curves are useful for determination of at what exposure amounts and threshold levels, effects which have both statistical and public health significance begin to occur. The method is applied to a ten year follow-up of a sub cohort of 7,343 members of the National Cancer Institute-funded Adventist Health Study. Up to 20 years of residence history was available. Analysis for prevalence of symptoms was conducted for four air pollutants— total oxidants, sulfur dioxide, nitrogen dioxide, and total suspended particulates. For each pollutant, cumulated exposures were calculated above each of five different thresholds. Statistically significant effects were noted for total suspended particulates, total oxidants, sulfur dioxide, past and passive smoking.     

Continuous Infrared Analysis of N2O in Combustion Products

Nitrous oxide (N₂O) levels in the atmosphere are increasing, potentially contributing to the greenhouse effect and depletion of stratospheric ozone. From a limited data base, combustion sources have been identified as a major anthropogenic source of N₂O. However, the existing data base (obtained by traditional grab sampling techniques followed by gas chromatographic analysis) is in question due to the discovery of a sampling artifact. A continuous on-line N₂O analyzer would enable and facilitate the accurate characterization of combustion sources over a range of operating conditions, and also aid in the development of an appropriate sampling technique. This paper addresses the development of a continuous measurement technique, and the evaluation and initial use of a field prototype continuous N₂O analyzer developed at the UCI Combustion Laboratory in cooperation with a major instrument manufacturer. The analyzer is capable of measuring N₂O levels down to a few ppm. The analyzer has been evaluated and used to study the N₂O emissions from a pulverized coal-fired boiler. The N₂O levels found with the analyzer are substantially lower than levels previously attributed to such sources. Initial N₂O measurements made with the analyzer suggest that N₂O levels are not a substantial fraction of the NO_X levels, as previously suggested.     

Development of Instrumentation for Continuous On-line Monitoring of Non-Methane Organic Carbon in Air Emissions

ABSTRACT

Non-methane organic carbon (NMOC) is a measure of total organic carbon in an air emission, excluding that from methane. Thus, it measures the total amount of carbon, irrespective of the structure and functional groups in the molecule. The U.S. Environmental Protection Agency (EPA) Method 25 is used for quantification of NMOC in emission sources and in ambient air. This method involves laboratory analysis of collected air samples and cannot be used for real-time measurements. It is prone to interferences from CO₂, CH₄, and CO, as well as moisture. In this paper, a novel method for continuous, on-line monitoring of NMOC in air emissions and ambient air is presented. Detection limits are at ppb levels, and interference of permanent gases have been eliminated.     

Recovery of an Aqueous Iron Phosphating/ Degreasing Bath by Ultrafiltration

Aqueous cleaners are emerging as safe and effective alternatives to solvent degreasers, but switching to water-based cleaners may create a new waste which is high in oil and grease and potentially RCRA hazardous. In the case study summarized here, one metal fabricator replaced a trichloroethylene degreaser with an aqueous iron phosphating/degreasing bath to clean and precondition steel parts. The aqueous bath typically lasted three to four months, until the buildup of oil in the tank began to sacrifice product quality and raise oil and grease levels in the rinse water discharge. Hauling away and replacing the spent cleaner resulted in more than 15,000 gallon/year of hazardous waste.

Ultrafiltration was selected as the most promising technology to recycle the aqueous cleaner and thereby reduce hazardous waste generation. Following pilot-scale testing at the Illinois Hazardous Waste Research and Information Center, on-site full-scale testing integrated the new waste reduction scheme directly into the facility’s production process. Ultrafiltration continuously filtered and returned clean process solution back to the iron phosphating/degreasing bath during normal plant operation, substantially reducing and maintaining oil concentrations at acceptable operating levels. The new process design successfully reduced hazardous waste generation 99.8 percent with a payback period of only 6.9 months.