Governmental environmental protection is commonly implemented by specifying a standard value of pollution, measured or actual, not to be exceeded. This article considers the standard for ozone pollution in the United States, interprets it using a hypothesis testing framework, and shows (in a simplified setting) how a statistician could implement this standard. The statistician's implementation is contrasted with the implementation by the U.S. Environmental Protection Agency. Some of the issues raised by these contrasting implementations are illustrated using ozone data from three areas in the United States. This article also examines potential biases in using data collected for standard compliance monitoring purposes to assess the health effects of ozone.

http://www.swrcb.ca.gov/water_issues/programs/tmdl/docs/303d_policydocs/402.pdf

Setting environmental standards: A statistician's perspective

Microbiological water quality guidelines have been established in most countries to protect the users from the risk of waterborne diseases. A guideline requires that a minimum number of water samples be collected during a period of time and analysed for an indicator organism. One or more summary statistics are computed and compared to limits specified in the guidelines. When at least one of the limits is exceeded, then certain actions must be taken. Since uncertainty is involved in the implementation of each of these requirements, the use of the guideline is intended to control and not to eliminate the risk from the use of impaired waters. The sources of uncertainties are discussed using two Canadian guidelines for microbiological recreational water quality. However, the methods used are applicable in general to guidelines' specification and use. Criteria are proposed for the selection of an indicator organism and the specification of its limits. The probabilities that quality of recreational water meets the federal guideline are estimated by simulation from the lognormal distribution. These probabilities reveal that imposing a single limit on the maximum eliminates the need for also imposing a limit on the geometric mean. The distributions of the maximum in samples of various sizes are derived by simulation and used to estimate the number of samples needed to detect a predetermined increase in the mean bacterial level. These distributions can be also used to determine the increase in the mean that a sample of a specific size can detect. Finally, the Ontario provincial guideline is compared to its federal counterpart. When the number of samples analysed is less than 15, the Ontario guideline is more conservative, but the reverse is true for larger sample sizes. Copyright © 1999 John Wiley & Sons, Ltd.

Guidelines for indicator bacteria in waters: uncertainties in applications

Environmental regulatory standards are intended to protect human health and environmental welfare. Current standards are based on scientific and policy considerations but appear to lack rigorous statistical foundations and may have unintended regulatory consequences. We examine current and proposed U.S. environmental regulatory standards for ozone from the standpoint of their formulation and performance within a statistical hypothesis testing framework. We illustrate that the standards can be regarded as representing constraints on a percentile of the ozone distribution, where the percentile involved depends on the defined length of ozone season and the constraint is stricter in regions with greater variability. A hypothesis testing framework allows consideration of error rates (probability of false declaration of violation and compliance) and we show that the existing statistics on which the standards are based can be improved upon in terms of bias and variance. Our analyses also raise issues relating to network design and the possibilities of defining a regionally based standard that acknowledges and accounts for spatial and temporal variability in the ozone distribution.

Statistical hypothesis testing formulations for U.S. environmental regulatory standards for ozone

Water pollution risk is concerned with assessing the impact of existing and future hazards that are associated with the beneficial uses of water. The focus of this article is on risks to human health due to exposure to water pollution. Some important statistical issues involved in the management of risk are discussed based on two pollution types: persistent toxic substances and microbiological contamination.


Keywords:

human health;
ecosystem health;
toxic substances;
microbiological contamination;
pollution indicators;
environmental standards and regulations

Water Pollution Risk

Abdel El-Shaarawi was born on December 31, 1942, in Zagazig, Egypt. He received his B.Sc. and M.Sc. degrees in 1964 and 1968 from Cairo University and his Ph.D. in Statistics in 1973 from University of Waterloo. In 1973 he began a career as a research scientist at the Canada Centre for Inland Waters in Burlington, Ontario. He has been part-time Professor in the Department of Mathematics and Statistics, McMaster University, since 1980, and Adjunct Professor in the Department of Statistics and Actuarial Sciences, University of Western Ontario, 1986 to 1996, and in the Department of Statistics, University of British Columbia, since 2001. During 1983--1984 he was Visiting Professor at the University of Metz and during 2002--2003 at the University of Genoa. For shorter periods he has been Visiting Professor at the University of Kuwait (1998, 1999), Masaryk University (1998, 1999) and King Saud University (2000). He is founding Editor of the journal Environmetrics and founding President of The International Environmetrics Society. He is an elected member of the International Statistical Institute and a Fellow of the Royal Statistical Society (United Kingdom), the American Statistical Association and the Modelling and Simulation Society of Australia and New Zealand. Awards include the Distinguished Achievement Medal of the ASA Section on Statistics and the Environment and the Citation of Excellence Award from the Government of Canada.

https://projecteuclid.org/download/pdf_1/euclid.ss/1081443231

A Conversation with Abdel H. El-Shaarawi

Microbiological monitoring of drinking water for fecal contamination is a legal requirement in most countries. The objective is to protect the users from water borne disease. We expressed The United States Drinking Water Regulations (DWR) in statistical terms and examined their probabilistic characteristics both analytically and by simulations. The DWR set upper limits on the mean coliform count and on the individual counts of all samples examined per month. Our results show that only an upper limit on the mean coliform count is basically sufficient for DWR. Copyright © 1999 John Wiley & Sons, Ltd.

Maximum microbiological contaminant levels

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Maximum microbiological contaminant levels