Because human activities impact the timing, location, and degree of pollutant exposure, they play a key role in explaining exposure variation. This fact has motivated the collection of activity pattern data for their specific use in exposure assessments. The largest of these recent efforts is the National Human Activity Pattern Survey (NHAPS), a 2-year probability-based telephone survey ( n=9386) of exposure-related human activities in the United States (U.S.) sponsored by the U.S. Environmental Protection Agency (EPA). The primary purpose of NHAPS was to provide comprehensive and current exposure information over broad geographical and temporal scales, particularly for use in probabilistic population exposure models. NHAPS was conducted on a virtually daily basis from late September 1992 through September 1994 by the University of Maryland's Survey Research Center using a computer-assisted telephone interview instrument (CATI) to collect 24-h retrospective diaries and answers to a number of personal and exposure-related questions from each respondent. The resulting diary records contain beginning and ending times for each distinct combination of location and activity occurring on the diary day (i.e., each microenvironment). Between 340 and 1713 respondents of all ages were interviewed in each of the 10 EPA regions across the 48 contiguous states. Interviews were completed in 63% of the households contacted. NHAPS respondents reported spending an average of 87% of their time in enclosed buildings and about 6% of their time in enclosed vehicles. These proportions are fairly constant across the various regions of the U.S. and Canada and for the California population between the late 1980s, when the California Air Resources Board (CARB) sponsored a state-wide activity pattern study, and the mid-1990s, when NHAPS was conducted. However, the number of people exposed to environmental tobacco smoke (ETS) in California seems to have decreased over the same time period, where exposure is determined by the reported time spent with a smoker. In both California and the entire nation, the most time spent exposed to ETS was reported to take place in residential locations.

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The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants.

Biodiversity is presently a minor consideration in environmental policy. It has been regarded as too broad and vague a concept to be applied to real-world regulatoy and managernentproblems. This problem can be corrected ifbio- diversity is recognized as an end in itsea and if measurable indicators can be selected to assess the status of biodiversity over time. Biodiversity, as presently understood, encom- passes multiple levels of biological organization. In thispa- per, I expand the three primay attributes of biodiversity recognized by Jerry Franklin - composition, structure, and function - into a nested hierarcby that incorporates ele- ments of each attribute at four levels of organization: re- gional landscape, community-ecosystem, population- species, andgenetic. Indicators of each attribute in terrestrial ecosystems, at the four levels of organization, are identified for environmental monitoring purposes. Projects to monitor biodiversity will benefit from a direct linkage to long-term ecological research and a commitment to test hypotheses relevant to biodiversity conservation. A general guideline is to proceed from the top down, beginning with a coarse-scale invent0 y of landscape pattern, vegetation, habitat structure, and species distributions, then overlaying data on stress lev- els to identiD biologically significant areas at high risk of impoverishment. Intensive research and monitoring can be directed to high-risk ecosystems and elements of biodiversity, while less intensive monitoring is directed to the total land- scape (or samples thereon. In any monitoringprogram, par- ticular attention should be paid to specifying the questions that monitoring is intended to answer and validating the relationships between indicators and the components of bio- diversity they represent

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Indicators for Monitoring Biodiversity: A Hierarchical Approach

The Environmental Protection Agency (EPA) provides access to information on a variety of topics related to the environment and strives to inform citizens of health risks. The EPA also has an extensive library network that consists of 26 libraries throughout the United States, which provide access to a plethora of information to EPA employees, scientists, and researchers. The EPA implemented a reorganization project to digitize their materials so they would be more accessible to a wider range of users, but this plan was drastically accelerated when the EPA was threatened with a budget cut. It chose to close and reduce the hours and services of some of their libraries. As a result, the agency was accused of denying users the “right to know” by making information unavailable, not providing an adequate strategic plan, and discarding vital materials. This case study explores the background of the digitization project, the practices implemented, and the critiques of the project.

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The Environmental Protection Agency

1 National Environmental Policy Act and Its Implementation2 Planning and Management of Impact Studies3 Simple Methods for Impact Identification Matrices, Networks and Checklists4 Description of Environmental Setting5 Environmental Indices and Indicators for Describing the Affected Environment6 Prediction and Assessment of Impacts on the Air Environment7 Prediction and Assessment of Impacts on the Surface Water Environment8 Prediction and Assessment of Impacts on the Soil and Ground Water Environment9 Prediction and Assessment of Impacts on the Noise Environment10 Prediction and Assessment of Impacts on the Biological Environment11 Habitat Methods for Biological Impact Prediction and Assessment12 Prediction and Assessment of Impacts on the Cultural (Historical/Archaeological) Environment13 Prediction and Assessment of Visual Impacts14 Prediction and Assessment of Impacts on the Socioeconomic Environment15 Decision Methods for Evaluation of Alternatives16 Public Participation in Environmental Decision Making17 Environmental MonitoringAppendixes

Environmental Impact Assessment

The cellular toxicity of carbon-based nanomaterials was studied as a function of their aspect ratio and surface chemistry. These structures were multiwalled carbon nanotubes, carbon nanofibers, and carbon nanoparticles. Their toxicity was tested in vitro on lung tumor cells. Our work clearly indicated that these materials are toxic while the hazardous effect is size-dependent. Moreover, cytotoxicity is enhanced when the surface of the particles is functionalized after an acid treatment.

Cellular Toxicity of Carbon-Based Nanomaterials

Environmental indices : theory and practice

Investigators in different environmental fields have reported that the concentrations of various measured substances have frequency distributions that are lognormal, or nearly so That is, when the logarithms of the observed concentrations are plotted as a frequency distribution, the resulting distribution is approximately normal, or Gaussian, over much of the observed range Examples include radionuclides in soil, pollutants in ambient air, indoor air quality, trace metals in streams, metals in biological tissue, calcium in human remains The ubiquity of the lognormal distribution in environmental processes is surprising and has not been adequately explained, since common processes in nature (for example, computation of the mean and the analysis of error) usually give rise to distributions that are normal rather than lognormal This paper takes the first step toward explaining why lognormal distributions can arise naturally from certain physical processes that are analogous to those found in the environment In this paper, these processes are treated mathematically, and the results are illustrated in a laboratory beaker experiment that is simulated on the computer

A Physical Explanation of the Lognormality of Pollutant Concentrations

Random Processes Stochastic Processes in the Environment Structure of the Book Theory of Probability Probability Concepts Probability Laws Conditional Probability and Bayes' Theorem Summary Problems Probability Models Discrete Probability Models Continuous Random Variables Moments, Expected Value, and Central Tendency Variance, Kurtosis, and Skewness Analysis of Observed Data Summary Problems Bernoulli Processes Conditions for Bernoulli Process Development of Model Binomial Distribution Applications to Environmental Problems Computation of B(n,p) Problems Poisson Processes Conditions for Poisson Process Development of Model Poisson Distribution Examples Applications to Environmental Problems Computation of P(l,t) Problems Diffusion and Dispersion of Pollutants Wedge Machine Particle Frame Machine Plume Model Summary and Conclusions Problems Normal Processes Conditions for Normal Process Development of Model Confidence Intervals Applications to Environmental Problems Computation of N(m,s) Problems Dilution of Pollutants Deterministic Dilution Stochastic Dilution Applications to Environmental Problems Summary and Conclusions Problems Lognormal Processes Conditions for Lognormal Process Development of Model Lognormal Probability Model Estimating Parameters of the Lognormal Distribution Three-Parameter Lognormal Model Statistical Theory of Rollback Applications to Environmental Problems Summary and Conclusions Problems Index

Environmental Statistics and Data Analysis

Personal exposure to ultrafine particles (UFP) can occur while people are cooking, driving, smoking, operating small appliances such as hair dryers, or eating out in restaurants. These exposures can often be higher than outdoor concentrations. For 3 years, portable monitors were employed in homes, cars, and restaurants. More than 300 measurement periods in several homes were documented, along with 25 h of driving two cars, and 22 visits to restaurants. Cooking on gas or electric stoves and electric toaster ovens was a major source of UFP, with peak personal exposures often exceeding 100,000 particles/cm3 and estimated emission rates in the neighborhood of 1012 particles/min. Other common sources of high UFP exposures were cigarettes, a vented gas clothes dryer, an air popcorn popper, candles, an electric mixer, a toaster, a hair dryer, a curling iron, and a steam iron. Relatively low indoor UFP emissions were noted for a fireplace, several space heaters, and a laser printer. Driving resulted in moderate exposures averaging about 30,000 particles/cm3 in each of two cars driven on 17 trips on major highways on the East and West Coasts. Most of the restaurants visited maintained consistently high levels of 50,000–200,000 particles/cm3 for the entire length of the meal. The indoor/outdoor ratios of size-resolved UFP were much lower than for PM2.5 or PM10, suggesting that outdoor UFP have difficulty in penetrating a home. This in turn implies that outdoor concentrations of UFP have only a moderate effect on personal exposures if indoor sources are present. A time-weighted scenario suggests that for typical suburban nonsmoker lifestyles, indoor sources provide about 47% and outdoor sources about 36% of total daily UFP exposure and in-vehicle exposures add the remainder (17%). However, the effect of one smoker in the home results in an overwhelming increase in the importance of indoor sources (77% of the total).

Wayne R. Ott

Papers

The National Human Activity Pattern Survey (NHAPS): a resource for assessing exposure to environmental pollutants.

Environmental indices : theory and practice

A Physical Explanation of the Lognormality of Pollutant Concentrations

Environmental Statistics and Data Analysis

Personal exposure to ultrafine particles