Depollution benchmarks for capacitors,batteries and printed wiring boards from waste electrical and electronic equipment (WEEE)

The article compiles and analyses sample data for toxic components removed from waste electronic and electrical equipment (WEEE) from more than 30 recycling companies in Switzerland over the past ten years. According to European and Swiss legislation, toxic components like batteries, capacitors and printed wiring boards have to be removed from WEEE. The control bodies of the Swiss take back schemes have been monitoring the activities of WEEE recyclers in Switzerland for about 15 years. All recyclers have to provide annual mass balance data for every year of operation. From this data, percentage shares of removed batteries and capacitors are calculated in relation to the amount of each respective WEEE category treated. A rationale is developed, why such an indicator should not be calculated for printed wiring boards. The distributions of these de-pollution indicators are analysed and their suitability for defining lower threshold values and benchmarks for the depollution of WEEE is discussed. Recommendations for benchmarks and threshold values for the removal of capacitors and batteries are given.     

Concepts of human exposure to air pollution

In recent years, considerable attention has focused on the concept of “human exposure” to environmental pollutants, but different investigators seem to have developed different definitions of this concept and used different approaches for estimating it. This paper reviews a number of “exposure” studies in a single environmental medium—air pollution—to see how others have defined this concept in the literature. Many previous investigators unfortunately calculate “exposures” by relying on data from fixed air monitoring stations, and they assume that people are located in the same place, usually their residential address, throughout a 24-h period. However, a second body of literature shows that fixed air monitoring stations do not necessarily reflect human exposures, because concentrations observed indoors—in homes, offices, factories, and motor vehicles—differ from those observed at fixed stations, and people usually spend considerable time in these locations. In an effort to standardize the nomenclature dealing with exposures, a definition is proposed in which the pollutant must come into contact with the physical boundary of the person. Then, exposure of person i to pollutant concentration c is viewed as two events occurring jointly: person i is present at a particular location, and concentration c is present at the same location. Mathematical definitions for “integrated exposure,” “average exposure,” and “standardized exposure” with various averaging periods also are introduced. Finally, two different yet compatible research approaches are suggested for determining human exposures to air pollution.     

Measurement of carbon monoxide concentrations in indoor and outdoor locations using personal exposure monitors

On 15 dates, 5000 measurements of carbon monoxide (CO) were made in downtown commercial settings in four California towns and cities (San Francisco, Palo Alto, Mountain View, and Los Angeles), using personal exposure monitoring (PEM) instruments. Altogether, 588 different commercial settings were visited, and indoor and outdoor locations were sampled at each setting. On 11 surveys, two CO PEM's were carried about 0.15–6 m apart, giving 1706 pairs of observations that showed good agreement: the correlation coefficient was r = 0.97 or greater, and the average difference was less than 1 ppm (μL/L) by volume. Of 210 indoor settings (excluding parking garages), 204 (97.1%) had average CO concentrations less than 9 ppm (μL/L); of 368 outdoor settings, 356 (96.7%) had average CO concentrations less than 9 ppm (μL/L). For a given date and commercial setting, CO concentrations were found to be relatively stable over time, permitting levels to be characterized by making only brief visits to each setting. The data indicate that most commercial settings experience CO concentrations above zero indoors, because CO tends to seep into buildings from vehicular emissions outside. Levels in these locations usually are not above 5 ppm (μL/L) and seldom are higher than the U.S. health-related ambient air quality standards for CO. However, indoor garages and buildings with attached indoor parking areas are exceptions and can experience relatively high CO concentrations.     

Trends in passenger exposure to carbon monoxide inside a vehicle on an arterial highway of the San Francisco Peninsula over 30 years: A longitudinal study

This paper describes a long-term trend study of passenger exposure to carbon monoxide (CO) inside a vehicle traveling on an arterial highway in northern California. CO exposure was measured during four field surveys on State Route #82 (El Camino Real) on the San Francisco Peninsula in 1980–1981, 1991–1992, 2001–2002, and 2010–2011. Each field survey took at least 12 months. Fifty trips from each survey—for a total of 200 trips—were matched by date, day of the week, and starting time of the day to facilitate comparisons over three decades. The mean net CO concentration of each trip was obtained by subtracting the background CO level from the average CO concentration for the entire trip. The mean net CO concentration (0.5 ppm) for 2010–2011 was only 5.2% of that (9.7 ppm) for 1980–1981. For the 50 trips, the average travel time for the 1980–1981 period (39.6 min) was only 8.3% higher than during the 2010–2011 period (36.3 min). The estimated round-trip distance on the highway was held constant at 11.8 miles. The reduction in the mean net CO concentration was attributed to more stringent CO emission standards on new vehicles sold in California since 1980. The state’s cold-temperature CO standard implemented in 1996 appeared to reduce high CO concentrations that were observed during the late fall and winter of 1980–1981. In addition, the observed standard deviation in concentration fell from 3.1 ppm in 1980–1981 to 0.2 ppm in 2010–2011, and the range of the 50 mean net CO concentrations narrowed from 14.9 ppm in 1980–1981 to 1.1 ppm in 2010–2011, but the relative variability, as indicated by the geometric standard deviation, remained the same. These results have important scientific implications for regulatory policies designed to control air pollution from motor vehicles.

Implications: Many developing countries launched or expanded their mobile source emission control programs in the 1990s, yet many of them do not have adequate inspection and maintenance (I/M) programs. The El Camino Real study shows the long-term public health benefits of more stringent motor vehicle emission standards for carbon monoxide (CO) on new cars and of an I/M program (Smog Check) on the existing fleet in California. The study provides a protocol for conducting standardized field surveys of in-vehicle exposure on a periodic basis. Such surveys would enable developing countries to assess the progress of their mobile source emission control programs.     

A Mathematical Model for Predicting Trends in Carbon Monoxide Emissions and Exposures on Urban Arterial Highways

Abstract

The roadway is one of the most important microenvironments for human exposure to carbon monoxide (CO). To evaluate long-term changes in pollutant exposure due to in-transit activities, a mathematical model has been developed to predict average daily vehicular emissions on highways. By utilizing measurements that are specific for a given location and year (e.g., traffic counts, fleet composition), this model can predict emissions for a specific roadway during various time periods of interest, allowing examination of long-term trends in human exposure to CO. For an arterial highway in northern California, this model predicts that CO emissions should have declined by 58% between 1980 and 1991, which agrees fairly well with field measurements of human exposure taken along that roadway during those two years. An additional reduction of up to 60% in CO emissions is predicted to occur between 1991 and 2002, due solely to the continued replacement of older cars with newer, cleaner vehicles.     

Interpreting Urban Carbon Monoxide Concentrations by Means of a Computerized Blood COHb Model

A practical, inexpensive computer model for estimating the level of blood carboxyhemoglobin (percent COHb) as a function of time for measured carbon monoxide concentrations (ppm CO) was developed from data from published studies on the assimilation of CO into the blood of human subjects. The model was designed to consider more realistically the dynamic characteristics of urban CO concentrations measured continuously at air monitoring stations, and it was applied to a year's CO data measured at the San Jose CA, air monitoring station (8760 hourly values).

The results indicate that the model can be used by local air pollution control agencies to calculate and print out estimated COHb levels alongside continuous CO concentration data. According to the model, the National Ambient Air Quality Standards (NAAQS) for CO sometimes were violated in San Jose without exceeding 2% COHb, as well as the converse: 2% COHb was exceeded without violating the standards. The model's estimated COHb levels also provided an advance warning of impending violation of the 8-hr CO NAAQS, and analysis of the model's response to CO "spikes" suggests that averaging periods as short as 10 or 15 minutes are necessary to preserve completely the dynamic characteristics of ambient CO monitoring data. These findings suggest that the margin of safety included in the current CO NAAQS, would not be the same if the actual time variation of measured CO concentrations is taken into account.     

Total Human Exposure: Basic Concepts,EPA Field Studies,and Future Research Needs

Historically, environmental regulatory programs designed to protect public health have monitored pollutants only in geophysical carrier media (for example, outdoor air, streams, soil). Field studies have identified a gap between the levels observed in geophysical carrier media and the concentrations with which people actually come into contact: their daily exposures. A new approach—Total Human Exposure (THE)—has evolved to fill this gap and provide the critical data needed for accurately assessing public health risk. The THE approach considers a three-dimensional "bubble" around each person and measures the concentrations of all pollutants contacting that bubble, either through the air, food, water, or skin. Two basic THE approaches have emerged: (1) the direct approach using probability samples of populations and measuring pollutant concentrations in the food eaten, air breathed, water drunk, and skin contacted; and (2) the indirect approach using human activity pattern-exposure models to predict population exposure distributions. Using the direct approach, EPA has conducted over 20 field studies for pollutants representing four groups—volatile organic compounds, carbon monoxide, pesticides, and particles—in 15 cities in 12 states. The indirect modeling approach has been applied to several of these pollutants. Additional research is needed in a great variety of areas. Even from the few projects completed thus far, the THE approach has yielded a rich new data base for risk assessments and has provided many surprises about the relative contribution of various pollutant sources to public health risk.     

Predicting Particulate (PM10) Personal Exposure Distributions Using a Random Component Superposition Statistical Model

ABSTRACT

This paper presents a new statistical model designed to extend our understanding from prior personal exposure field measurements of urban populations to other cities where ambient monitoring data, but no personal exposure measurements, exist. The model partitions personal exposure into two distinct components: ambient concentration and nonambient concentration. It is assumed the ambient and nonambient concentration components are uncorrelated and add together; therefore, the model is called a random component superposition (RCS) model. The 24-hr ambient outdoor concentration is multiplied by a dimensionless “attenuation factor” between 0 and 1 to account for deposition of particles as the ambient air infiltrates indoors. The RCS model is applied to field PM₁₀ measurement data from three large-scale personal exposure field studies: THEES (Total Human Environmental Exposure Study) in Phillipsburg, NJ; PTEAM (Particle Total Exposure Assessment Methodology) in Riverside, CA; and the Ethyl Corporation study in Toronto, Canada. Because indoor sources and activities (smoking, cooking, cleaning, the personal cloud, etc.) may be similar in similar populations, it was hypothesized that the statistical distribution of nonambient personal exposure is invariant across cities.