When tuberculosis-infected traveler Andrew Speaker, who ironically is a personal injury lawyer, flew commercially in May of 2007, he caused an international crisis. With help from the Center for Disease Control, the fear spread that he had potentially exposed his fellow passengers to this contagious airborne disease. Some two months later, his diagnosis was changed to a more treatable form of tuberculosis.
This widely publicized incident, involving transcontinental flights, the CDC, Border Patrol, and Congress, to name a few entities, magnified the general public’s concerns over air quality. The unseen can be extremely dangerous.
Yet, normal daily breathing is packed with possible health hazards that never receive this type of intense publicity. And these hazards probably pose far more serious consequences.
For example, when babies are exposed to tobacco smoke, they are more susceptible to developing asthma. Statistics show that asthma afflicts about 20 million Americans, including 6.3 million children. Since 1980, children under five have sustained the biggest growth in asthma cases.
As warmer temperatures are recorded from global warming, air and water pollution can increase, which in turn, harms human health. For example, ground-level ozone can damage lung tissue, and is especially harmful for those with asthma and other chronic lung diseases.
In your home, when you look down, you are likely to see a big source of dust mites, your carpeted floor. An individual’s allergies may result from plant pollens and mold spores, part of the outdoor air, or these dust mites found inside one’s home.
In the past, pollution experts have recommended that carpets be replaced with hard flooring, such as wood, vinyl, or tile. This advice may now be out-of-date, just like studies that go back and forth on food groups that help prevent cancer. Today, environmental engineers are looking at other sources of indoor air pollution such as the building materials used in construction.
Studies identify new pollutants previously thought to be safe
John Little, a 1996 National Science Foundation (NSF) Faculty Early Career Development Program CAREER Award recipient for his work on indoor pollution and a professor of civil and environmental engineering (CEE) at Virginia Tech, has identified a method for predicting the rate that specific volatile organic compounds (VOCs) are released from one such material – the commonly used vinyl flooring. He is now using his investigation technique to determine if other types of building materials made from polymers are also releasing VOCs and, if so, at what rate.
The three contaminants Little identified in vinyl flooring are pentadecane, tetradecane, and phenol. According to the Agency for Toxic Substance and Disease Registry, potential health effects of long-term, low-level exposure to phenol include increases in respiratory cancer, heart disease, and effects on the immune system.
“Because we spend most of our time indoors, exposure to indoor air pollutants may be orders-of-magnitude greater than that experienced outdoors,” Little said. “Volatile emissions are a probable cause of acute health effects and discomfort among building occupants and are known to diminish worker productivity.”
After using his model to predict VOC emissions from vinyl flooring, he is now turning his attention to semivolatile organic compounds (SVOCs) such as plasticizers, flame retardants, and biocides. “These constituents are added to a variety of products to enhance performance and are often present at considerably higher concentrations than their more volatile counterparts. There are serious health concerns associated with SVOCs in general and with phthalate plasticizers in particular,” he added. A plasticizer represents any of a variety of substances added to a plastic or other material to keep it soft and pliable.
Phthalates are found in numerous everyday items such as toys, medical equipment, paints, inks, vinyl flooring, hairsprays, deodorants, nail polish, perfumes, and shampoo. Flame retardants are found in common place office articles such as computers, electronics, electrical equipment, cables, and foam furniture.
Little believes his preliminary studies, using the process he developed for determining the rate of volatile emissions from vinyl flooring, are showing signs of success at predicting the emission rate of SVOCs from polymeric materials.
Will nanotechnology affect air pollution?
Nanostructured materials--in the form of an alloy such as a metal or a ceramic -- “are made of the same atoms as their more common forms, but the atoms are arranged in nanometer-size clusters which become the...building blocks of the new materials,” wrote Richard Siegel, a materials engineer at Rennselaer Polytechnic Institute who is considered a pioneer of these substances, in 1985.
So, for more than 20 years, engineers and scientists have manipulated nanoparticles in attempts to create new materials. But, as Linsey Marr, also an NSF CAREER award recipient, pointed out, “although the growth of the nanotechnology industry has been breathtakingly rapid, very little is known about the health and environmental effects of manufactured nanoparticles.” Could they prove to go the way of vinyl flooring?
These nanomaterials include fullerenes, carbon nanotubes, and other types of engineered particles that are smaller than 100 nanometers, yet have great potential for use in drug delivery, medical imaging, fuel cells, superconductors, photovoltaics, quantum computers, environmental remediation, and other consumer products.
Exposure to nanoscale particles may occur naturally. Small particles found in motor vehicle exhaust are already recognized as a health threat that can cause lung cancer and cardiovascular disease. The added threat, Marr said, “is that compared to larger particles, nanoscale particles are able to penetrate deeper into the lung, where they or compounds adsorbed on them can enter the bloodstream.”
Marr, an assistant professor of CEE, and Peter Vikesland recently received a National Science Foundation grant of $350,000 to study the transport and fate of manufactured nanoparticles in the environment. Marr is establishing a nanoparticle laboratory for environmental and public health studies. Vikesland, an associate professor in the Via CEE Department, also holds an NSF CAREER award on the formation and reactivity of nanoscale corrosion products.
The NSF grants allow the researchers to study the transport, transformation, and fate of manufactured nanomaterials in atmospheric, aquatic, and terrestrial environments. “A key component of this project is to examine how ‘fresh’ versus atmospherically ‘aged’ nanomaterials behave in aquatic and terrestrial systems,” Marr said.
Novel efforts underway to improve certainty of estimating pollution emissions
Simultaneously, Marr is working with her graduate students on a unique approach to measuring air pollution emissions. They have mounted instruments that measure pollutant concentrations and wind velocity on the top of a van with an extendable mast — “like a TV news van,” she explained. The research team is parking the van in various locations such as Roanoke, Va., the Shenandoah Valley of Virginia, and Baltimore, Md.
They call the van the FLAME or the Flux Lab for the Atmospheric Measurement of Emissions. As the instruments collect the air samples, they are funneled through the various measurement devices to measure pollutants. The researchers are focusing on human generated emissions of carbon dioxide, a greenhouse gas; nitrogen oxides and organic compounds, key ingredients in smog formation; and airborne particles, culprits for both health effects and poor visibility.
“Current estimates of air pollutant emissions are highly uncertain,” said Marr, who developed a fuel-based motor vehicle emission inventory for central California while a doctoral student at the University of California (UC) at Berkeley. “We anticipate that our measurements will add considerable new insight to the quantification of different types of emissions. Scientists can use this information to improve their understanding of air pollution, and policy makers can devise more effective plans to improve air quality.”
Marr explained that her team has chosen locations with known air quality issues to get a better idea what the causes of the problem are. It might be coming from industry, the community itself, or from surrounding communities that are upwind. Better identification of the source will allow the researchers to make the appropriate recommendations.
The study, in its second year, will last five years, supported by the $400,000 that comes with the CAREER grant. Every CAREER project also includes an educational component, and Marr is taking the research van to K-12 schools near the field sites and offering tours for students. She also plans to test the effectiveness of new technology in her Introduction to Environmental Engineering class. Each student will have a remote control keypad to enter answers to questions Marr poses during class. She hopes this method of instant feedback and active participation will prove to increase “students’ retention of material and the environmental engineering field’s retention of students.”
Little, Marr and Vikesland represent the nationally ranked environmental and water resources engineering program, comprised of 20 faculty members and about 115 graduate students within the Via CEE Department, a top 10 program according to the “America’s Best Graduate Schools 2008” survey released by U.S. News and World Report. Little and Marr recently received an NSF project to look at emissions of phthalate plasticizers and their interaction with airborne particles. Little also received a NSF grant with Eva Marand of chemical engineering to investigate emissions of other VOCs from other building materials.
Elizabeth Crumbley contributed to this article.