Professor Of Environmental Engineering Research Articles

The Forest and the Trees: How Population-Level Health Protections Sometimes Fail the Individual

The Forest and the Trees: How Population-Level Health Protections Sometimes Fail the Individual

When It Comes to Electric Vehicle Emissions, Location Matters

In an effort to boost sales the Chinese government recently announced it would waive the 10% sales tax on domestic electric cars on top of government subsidies totaling up to $19,000 per car.1 But despite their green reputation, on a per-kilometer basis electric cars in China cause over 3.5 times more air pollution–related premature deaths than gasoline-powered cars, according to new estimates calculated for the country’s 34 largest cities.2 In the study, the researchers calculated emissions per person-km traveled—that is, a person traveling 1 km in a vehicle (if 15 people travel 10 km in a bus, the bus accumulates 150 person-km). They considered five vehicle types: electric cars (not including hybrids), electric bicycles and scooters (e-bikes), gasoline cars, diesel cars, and diesel buses. They estimated tailpipe emissions for gasoline and diesel vehicles based on emissions standards and figures published in the peer-reviewed literature. Electric vehicles do not produce combustion emissions themselves; instead, their emissions impact comes from the power plants that produce the electricity they use. The vast majority of electricity in China is coal-fired2 (compared with slightly less than 50% in the United States3). The authors modeled the fraction of fine particulate matter (PM2.5) emissions inhaled by the population to estimate total attributable excess mortality. “This is the pollutant with the most well-studied health impacts, including irrefutable association with premature mortality,” says coauthor Christopher R. Cherry, an assistant professor in the University of Tennessee–Knoxville Department of Civil and Environmental Engineering. Electric vehicle emissions derive not from gasoline or diesel but from coal and other energy sources used to power the electricity grid. Although vehicle-specific mortality varied greatly from city to city, electric cars were estimated to cause more premature deaths than gasoline cars in 33 of the 34 cities surveyed.2 “Emissions from coal-fired power plants are comparatively high in China because of lower-quality coal and fewer plants using emission-control technologies,” explains report coauthor Julian D. Marshall, an assistant professor of environmental engineering at the University of Minnesota, Minneapolis. In Shanghai, for instance, power-plant emissions associated with electric cars caused an estimated 26 excess deaths annually per 10 billion person-km versus 9 excess deaths for gasoline cars. Diesel cars caused an estimated 90 excess deaths per 10 billion person-km. Diesel buses, which have lower emissions per person-km than diesel cars because they carry more people, caused an estimated 32 excess deaths, and e-bikes performed the best, causing only 3 estimated excess deaths per 10 billion person-km per year. Beijing exempts battery-electric vehicles from its monthly license-plate lottery to determine who is allowed to buy a new car. In March 2011 nearly 400,000 people vied for the monthly allotment of 17,600 license plates.6 In another effort to reduce traffic emissions, the city also occasionally uses odd/even rationing based on license plate number to control the number of cars on the road.7 Not surprisingly, the implications of this research for other countries are variable. Vietnam, for example, depends much more on natural gas and hydropower than coal for its electric power, says Cherry, such that electric cars there cause one-third as much pollution as gasoline cars and one-tenth as much pollution overall as they do in China. Conversely, he says, in India, average power-sector emissions of PM2.5 are 10% greater than in China, causing more pollution per kilometer per electric car. “It is important to remember that electric vehicles are only as clean as the electricity that charges them, and a clean energy future includes both electric vehicles and a cleaner electricity grid,” says Don Anair, a senior analyst and engineer at the Union of Concerned Scientists (UCS). Anair notes that the U.S. grid is cleaner than China’s as a result of clean-air regulations and increased investment in renewable electricity (the U.S. investment in renewable energy ranks second in the world, just behind China4). The emissions intensity of the U.S. grid—that is, the emissions per unit of power produced—will continue to improve as older, unimproved coal-fired plants are retired, he says. A report from the UCS released in April 2012 found that even in the U.S. region with the most emissions-intensive electricity grid, greenhouse-gas emissions attributable to electric vehicles are equivalent to those produced by gasoline cars that get 31–40 miles per gallon.5 That report did not address mortality attributable to PM2.5 exposure.

AIR POLLUTION: The Oxidative Punch of Wildfires

Thick smoke routinely cloaks Southern California hills, highways, and neighborhoods during this region’s autumn wildfire season, with drought contributing to worse fires than usual in the past two years. Wildfire emissions generate larger aerosols than those produced by vehicles—up to 0.4 micrometers (μm) in diameter compared with less than 0.15 μm—according to a new study led by Constantinos Sioutas, a professor of civil and environmental engineering at the University of Southern California, Los Angeles. In findings published online 6 January 2009 ahead of print in Environmental Science & Technology, the larger particles emitted by fires activated a standard assay of oxidative stress even more potently than traffic pollutants. The performance of different types of particulate matter in oxidative stress tests may provide clues as to how these pollutants cause damage such as proinflammatory or cytotoxic effects. Sioutas and colleagues took advantage of wildfires burning in Southern California in October 2007 to investigate their impact on urban air quality relative to traffic pollutants, with a special emphasis on particulate matter small than 2.5 μm in diameter (PM2.5). The researchers collected air samples on the University of Southern California campus, within 150 meters of a busy freeway near downtown Los Angeles. A series of wildfires had started on 20 October 2007, burning more than 500,000 acres of land and stretching from Santa Barbara County to the Mexican border. When air samples were collected on October 24, 25, and 27, fires were raging within 20 miles of the collection site. Measurements were taken from 4:30 p.m. until 10:30 a.m. the following day to capture pollution from evening and morning rush hour traffic as well as from the fires themselves. The fires in Los Angeles County were under control by October 30; post-fire samples collected on November 1 and 14 represented mostly traffic emissions. Compared with post-fire samples, samples collected on the three fire days in October contained a higher number of particles larger than 0.1 μm in diameter. Both carbon monoxide and nitrogen monoxide levels increased by threefold during fire days, while levels of other air pollutants—ozone, nitrogen dioxide, most polycyclic aromatic hydrocarbons, iron, copper, chromium, zinc, nickel, and vanadium—remained the same. In addition, during the fire period there was an approximate doubling in several indicators for biomass burning: levoglucosan, water-soluble organic carbon, and various minerals (magnesium, phosphorus, potassium, and manganese). Various chemical components of PM2.5 fuel oxidative stress and are toxic to human cells. Working in collaboration with James Schauer of the University of Wisconsin–Madison and Flemming Cassee of the National Institute of Health and the Environment of the Netherlands, the Sioutas team measured cellular toxicity with two standard tests of oxidative stress, the dithiothreitol (DTT) assay and the macrophage reactive oxygen species (ROS) assay. Particles collected during October showed nearly 5 times more DTT activity than those collected in November. In contrast, the macrophage ROS assay, a known indirect measure for combustion pollutants from vehicles that is more responsive to transition metals, peaked in November. “In this study we demonstrated that a substantial portion of the oxidative potential of air pollution during fires can be attributed to the wildfires,” says Sioutas. He attributes the difference to the increased water-soluble organic compounds that are abundant in wood smoke and show more activity in the DTT assay. According to Sioutas, the elevated levels of water-soluble organic carbon also mean wood smoke particles are more readily absorbed by the body than is PM from traffic sources. The DTT and macrophage ROS assays “appear to respond to different components of PM2.5,” notes Ted Russell, a professor of environmental engineering at the Georgia Institute of Technology in Atlanta. This observation suggests that environmental scientists need to further characterize the two redox assays. A detailed analysis of how these assays respond to specific PM2.5 components obtained from different environmental samples at different times “will lay a foundation for understanding the characteristics of ambient PM2.5 that have the greatest health impacts,” says Russell. Sioutas says that the larger particles from wildfires can persist longer in the atmosphere and infiltrate buildings about twice as effectively as traffic pollutants. He recommends that people living near wildfires try to remain inside, shut their doors and windows, and run an air conditioner with a good filter to recirculate the indoor air. “If you don’t have an air conditioner, go to an indoor mall or other public place that recirculates indoor air,” he says. Other practical suggestions are included in the State of California guidelines for wildfire smoke at http://www.arb.ca.gov/smp/progdev/pubeduc/wfgv8.pdf.

Chemical Exposures: The Sweet Scent on Baby’s Breath?

Synthetic fragrances known as polycyclic musks are added to soap, shampoo, deodorant, cleaning agents, cosmetics, and other consumer products. Now they are also turning up in human breast milk. In the first U.S. study to measure polycyclic musks in breast milk, environmental toxicologist Kurunthachalam Kannan at the New York State Department of Health and colleagues found the highest levels ever recorded in nursing mothers. Over the past 20 years, polycyclic and other synthetic musks have replaced expensive natural musks derived from endangered wildlife. The two most widely used polycyclic musks, HHCB and AHTN, make up 90% or more of the U.S. and European markets for these compounds. Synthetic musks are used to mask chemical odors in products labeled “unscented”—though they aren’t added to products labeled “fragrance-free.” Kannan measured polycyclic musks in milk samples collected from 39 nursing women in Massachusetts. The average concentration of HHCB was five times higher than that measured in European breast milk samples 10 years ago, and the average AHTN concentration was twice that detected in another European study in 1999. Using these averages and the average consumption of breast milk, Kannan estimated that babies may ingest 1,830 ng of HHCB and 5656 ng of AHTN per day. Kannan believes pregnant women should avoid products with musk fragrances because, he says, “Not much is known about the toxicity of these compounds to humans, let alone to babies.” The findings are reported in the 1 June 2007 issue of Environmental Science & Technology. Polycyclic musks are emerging pollutants, and little is known about their human or environmental health effects. Musk compounds in products like lotions can readily penetrate the skin. Inhaling airborne polycyclic musks (for example, from perfumes and air fresheners) offers another source of exposure. In an earlier study published in the November 2005 issue of Chemosphere, Kannan showed that polycyclic musks accumulate in human fat tissue at concentrations up to 1 ppm. Moreover, in the January 2005 issue of EHP, Till Luckenbach and David Epel showed that polycyclic musks blocked the activity of multidrug efflux transporters that pump toxicants from cells to protect them from damage. Inhibiting these pumps allows pollutants to enter cells and accumulate. Manufacturers do not disclose the quantity of musk compounds added to consumer products yearly. Musk ingredients often are not listed on product labels, or they are called simply “fragrance” or by the trade names galaxolide (for HHCB) or tonalide (for AHTN). “Our everyday experience suggests that there are more fragrances in consumer products and at higher concentrations than ever before,” says Keri Hornbuckle, a professor of environmental engineering at the University of Iowa. Hornbuckle’s group has measured polycyclic musks in surface water and outdoor air samples in rural and urban areas. “We find them everywhere,” she says, “and their concentration is proportional to the population of the area where samples are collected.” Concentrations of HHCB in Lake Erie doubled between 1990 and 1998, Hornbuckle reported in the 15 September 2006 issue of Environmental Science & Technology. Hornbuckle also reported in the November 2006 Archives of Environmental Contamination and Toxicology that polycyclic musks reduce the growth of the juvenile and larval stages of the freshwater mussel Lampsilis cardium, a sentinel for vulnerable aquatic species in ecological systems. As scientists learn more about the impact of polycyclic musks on organisms and ecosystems, “we may become more concerned about exposure in humans,” Hornbuckle says.

Paving Paradise: The Peril of Impervious Surfaces

Paved surfaces are quite possibly the most ubiquitous structures created by humans. In the United States alone, pavements and other impervious surfaces cover more than 43,000 square miles—an area nearly the size of Ohio—according to research published in the 15 June 2004 issue of Eos, the newsletter of the American Geophysical Union. Bruce Ferguson, director of the University of Georgia School of Environmental Design and author of the 2005 book Porous Pavements, says that a quarter of a million U.S. acres are either paved or repaved every year. Impervious surfaces can be concrete or asphalt, they can be roofs or parking lots, but they all have at least one thing in common—water runs off of them, not through them. And with that runoff comes a host of problems.

Review of Water Resources Planning by Andrew A. Dzurik

This is the third edition of a basic text on the broad subject of water resources planning. The author has apparently added new material in the form of a Web site listing, some new text, and new tables to update dated material, such as a listing of models in use. All-in-all, however, the text appears to be little changed from the author’s first two editions. In any event, the author offers an interesting sample of water resources planning and management topics, written at a basic level. This is a very broad field, and, as the author acknowledges, it is difficult to stipulate prerequisites for learning in such a broad field. Prerequisites, according to the author, would be basic math and science, intellectual maturity, and an interest in the subject. The author is a professor of environmental engineering at the FSU-FAMU College of Engineering, located at Florida State University. He has served as a resident scholar with the Corps of Engineers where he obtained federal experience. He teaches and writes in the fields of water planning and environmental policy. As with the earlier editions, the current volume is a clear and straightforward presentation of a range of topics. These include hydrology, law, organization, legislation, the planning process, economics, applications, models, environmental issues, and future directions. Having also prepared a text on the same topic, this reviewer concurs in general with the book’s organization and scope but would differ on the details of the list of important topics. One surprise was the author’s chapter on ‘‘Federal Water Agencies and Legislation.’’ The reviewer expected to find text about agency structure, programs, and politics, but the chapter is really an extension of the previous one, and covers water and environmental law. The chapter’s introduction specifies that it is divided into two parts, but the second part dominates. Moreover, the chapter’s introduction specifies that it is an introduction to the federal ‘‘regulatory scheme,’’ but federal agency resource activities go beyond regulatory programs. The book apparently meets a demand for a clear presentation of the basic aspects of water resources planning. Its features that seem worthy of praise include broad coverage, a clear presentation, and the author’s success in writing to a wide audience. Also, the new inclusion of a listing of Web sites should be useful. Although the book is comprehensive in scope, a number of important topics are either left out or not covered in detail. For example, there is no coverage of irrigation, one of the most important water management topics in the West. Similarly, there is no coverage of planning for wastewater treatment infrastructure. Also, in the midst of one of the worst droughts in memory for parts of the country, there is no mention of droughts or drought contingency planning. Environmental issues in planning seem mostly relegated to a chapter on ‘‘other planning issues.’’ Knowing the author is more up-to-date than that, this reviewer suspects

Geophysicists

Ben Dysart, a professor of environmental engineering at Clemson University, is this year's recipient of the McQueen Quattlebaum Faculty Achievement Award. The award is the university's most prestigious honor given to a member of the engineering faculty.

The Future of Water Supply

The following Roundtable Is an edited version of the panel discussion that highlighted the Second Century Luncheon, which, on July 11, capped the Centennial Conference at St. Louis, Mo. Introduced by AWWA President Kenneth J. Miller, the panel consisted of Henry J. Graeser, senior consultant, Black & Veatch Consulting Engineers; James V. LaFrankie, president, American Water Works Service Co.; Daniel A. Okun, professor of environmental engineering. University of North Carolina; and Henry J. Ongerth, former chief of sanitary engineering, California Department of Public Health. The panel was questioned by Robert Blanchard of the St. Louis Globe Democrat, Martha Shirk of the St. Louis Post‐Dispatch, and Mike Owens of radio station KM OX.

Future Water Systems: How Will They Differ?

The following discussion took place Jun. 26, 1978, at Atlantic City, N.J. Moderated by Paul C. Notari, AWWA director of publications, the panel consisted of Paul D. Haney, Black & Veatch Consulting Engineers, Kansas City, Mo.; Francis M. Middleton, director, drinking water quality research center, Florida International University, Miami, Fla.; and Daniel A. Okun, professor of environmental engineering, University of North Carolina, Chapel Hill, N.C.

Power Generation and the Environment

Electricity generating plants emit more than one-half of the sulfur oxide pollutants in the United States…nearly 20 million tons a year. What are the alternatives? How would they affect the environment? This assessment is based on a paper presented by Professor Eliassen to the National Academy of Sciences Symposium on “Power Generation and the Environment” during the 108th annual meeting April 26, 1971. It is published here with the permission of the Academy. The author is professor of environmental engineering, Stanford University, and a member of the General Advisory Committee of the Atomic Energy Commission.