Analysis of Respirable Fractions in Atmospheric Particulates via Sequential Filtration

It has long been recognized that information on particle size distributions in atmospheric aerosals is necessary for meaningful evaluations of potential health hazards. Such information is also important in establishing particulate sources, transport, transformations, and sinks, especially in combination with elemental and chemical data. While instruments exist to collect size segregated samples of particulates, they are too complex and expensive to encourage use of multiple units in field situations.     

Emissions Control and Ambient Air Quality at a Secondary Steel Production Facility

Steel production from electric arc furnaces has been continuously rising over the past few years. The trend is expected to continue due to both the anticipated increase in demand for steel, and to the replacement of obsolete open hearth furnaces. In 1972 steel produced in electric arc furnaces, which makes up 25 to 30% of the annual United States steel production, was produced primarily from recycled scrap steel in approximately 300 electric arc furnaces operated by 99 companies at 121 locations.¹ Over half of these furnaces are smaller than 50 tons, and many are located in small bar mills producing a variety of merchant steel products.     

The Value of Continuous Monitoring to the User

Potential benefits of a continuous monitoring program are presented in the form of questions that can be asked in connection with the information gained from the program. These questions are:

1. Are there process problems of which we are unaware?

2. Will this information be useful in the design of the next plant?

3. Can the information be used for improved process control?

4. Are we losing valuable material?

5. Can we use this information to modify our process for reduced pollution?     

Interpreting the eight-hour national ambient air quality standard for carbon monoxide

There are two principal approaches to the 8-hour carbon monoxide standard: (1) 8-hour moving averages that culminate with every clock hour, and (2) nonoverlapping averages for consecutive 8-hour intervals. Examination of 1972 data for three example sites (Newark, NJ, Camden, NJ, and Spokane, WA) shows that the maximum and the “second high” control values derived from moving averages can be at least 20% higher than corresponding values detected by the consecutive 8-hour intervals. The natural fluctuation in the time of day when the maximum occurs and the variability in episode length make it doubtful that any framework of consecutive 8-hour intervals can adequately portray the essential characteristics of CO exposure. Prudence recommends choice of the moving 8-hour average as more sensitive to actual maximum levels and to short episodes, more faithful to the body’s integrating response to CO exposure, and more equitable in presenting comparisons among stations with differing patterns of daily variation.     

Unleaded Gasoline Shortages and Fuel Switching

The use of leaded gasoline in automobiles equipped with catalytic converters causes deactivation of the converters and leads to significant increases in emissions of reactive hydrocarbons, a precursor of ozone. Such fuel switching may be a contributing factor to the increase in photochemical smog levels recently observed in the South Coast Air Basin (SOCAB).     

Assessment of Arsenic Losses during Ashing: A Comparison of Two Methods Applied to Atmospheric Participates

A comparison was made of over 300 pairs of arsenic results from instrumental neutron activation and flameless atomic absorption analyses of atmospheric particulates collected on glass fiber filters. Atomic absorption analyses involved low temperature ashing of filters at high power levels. No matrix modification chemicals were added to the acid extract which was analyzed. Neutron activation results are on the average 9% higher than those obtained by atomic absorption and the difference is statistically significant. This small difference is probably due to the analytical techniques or acid extraction and not in any important way to losses during low temperature ashing. This conclusion is in sharp contrast to other recently reported situations where low temperature ashing losses in analyzing atmospheric particulate were sizable. Although the atmospheres sampled differed somewhat between these situations the most obvious difference was in the combustibility of the filters used in sampling.     

Uncertainty requirements of the European Union’s Industrial Emissions Directive for monitoring sulfur dioxide emissions: Implications from a blind comparison of sulfate measurements by accredited laboratories

When annual average PM_2.5 (fine particulate matter sized 2.5 microns and less) data for 2005 became available in April 2006 and the 3-yr average PM_2.5 concentration in an area just north of the Houston Ship Channel reached 15.0 µg/m³, the Texas Commission on Environmental Quality (TCEQ) initiated daily collection of quartz fiber as well as Teflon PM_2.5 filter samples for chemical speciation analysis. The purpose of the chemical speciation analysis was to use the speciation data, together with meteorological data and hourly TEOM (tapered element oscillating microbalance) PM_2.5 mass data, to identify the causes of the high PM_2.5 concentrations affecting the monitoring site and the neighborhood. The ultimate purpose was to target emission reduction efforts to sources contributing to the high measured PM_2.5 concentrations. After a year of data collection, it was recognized that a specific source, unpaved driveways and loading areas along the Ship Channel and dirt tracked onto Clinton Drive, the main artery running east-west north of the Ship Channel, were the primary cause for the Clinton Drive site's measuring PM_2.5 concentrations significantly higher than other sites in Houston. The source characterization and remediation steps that have led to sustained reduced concentrations are described in this paper.

Implications: With PM_2.5 exceedances it can be essential to have or develop chemical speciation data as part of the process of identifying the source types causing exceedances of an annual standard. Positive matrix factorization (PMF) analysis proved to be a powerful tool that identified the two locally emitted species contributing to exceedances, which did not occur at other sites in the region. They were calcium sulfate (gypsum), an industrial by-product, and soil minerals. Other data analysis approaches were necessary to distinguish North African dust events, which PMF failed to identify.     

Statistical Assumptions Matter in Data Analysis for Texas Ozone Nonattainment Sites

Strategies for control of ozone aim at regulation of its chemical precursors, non-methane organic compounds (NMOC) and nitrogen oxides (NOx). It is therefore important to analyze how these precursors vary temporally and geographically. This study finds significant and important differences among four Texas ozone nonattainment sites, Dallas, Ft. Worth, El Paso, and Houston, for 1984, 1985, and 1986 for NMOC, NOx, and their ratio NNR. These differences were detected through nonparametric analysis of variance and Student-New-man-Keuls’s test for multiple comparisons on rank-transformed data. A noteworthy feature of the data analysis is its attention to the assumptions underlying the statistical methods. Classical models based on normal or lognormal theory had to be abandoned for lack of realism. It is demonstrated how alternative models may be applied to yield appropriate, rather than inappropriate, conclusions.