Grantee Research Project Results
Final Report: Solsource 3-In-1: Providing Clean Energy to the Poorest 2.5 Billion at a Price They Can Afford
EPA Grant Number: SU834746Title: Solsource 3-In-1: Providing Clean Energy to the Poorest 2.5 Billion at a Price They Can Afford
Investigators: Powers, Catlin Ishihara , Spengler, John D. , Frank, Scot G. , Qian, Amy , Amatya, Reja , Zhang, Wendi Xiaowen , Jia, Huaze , Kulper, Sloan , Ram, Rajeev , Tai, Xiamao , Yang, Xudong , Wilson, David Gordon , Ezzati, Majid
Institution: Harvard University , Massachusetts Institute of Technology , Tsinghua University , Qinghai Normal University
EPA Project Officer: Page, Angela
Phase: II
Project Period: August 15, 2010 through August 14, 2012 (Extended to August 14, 2013)
Project Amount: $75,000
RFA: P3 Awards: A National Student Design Competition for Sustainability Focusing on People, Prosperity and the Planet - Phase 2 (2010) Recipients Lists
Research Category: Pollution Prevention/Sustainable Development , P3 Challenge Area - Air Quality , P3 Challenge Area - Chemical Safety , P3 Awards , Sustainable and Healthy Communities
Objective:
The objective of this research was to develop a novel solar energy intervention with the goal of reducing indoor air pollution exposures in nomadic households in western China.
Globally, more than 2.5 billion people rely on solid fuels (dung, wood, crop residues, and coal) to meet their basic energy needs.1 These people suffer health-threatening exposure to PM2.5 and CO from burning these fuels in indoor stoves, and as many as 4 million people die annually from related illnesses, 56% of whom are children under the age of five.2 Within China alone, more than 500,000 deaths are estimated annually from illnesses related to burning dirty fuels in indoor stoves.3
Figure 1. Map of Himalayan Region.
Our study took place in Qinghai Province, to the southeast of Qinghai lake, on the Himalayan Plateau in western China at 40°N latitude. People in this region are at high risk for smoke-related illnesses due to use of low-quality fuels, high elevations, and well-insulated homes. The average elevation on the plateau exceeds 4,500 m and human settlements can be found from 2,000 to 5,000 m. At these altitudes, few trees grow and methane digesters struggle to continue their production during the cold months from October through May. The primary source of fuel is yak and sheep dung, with wood mixed in at the lower altitudes. Due to their relatively low energy density, dung and wood produce more CO and PM2.5 per unit of energy extracted than any other common fuel source.4 Further, at these high altitudes, low partial pressures of oxygen prevent the completion of combustion reactions, leading to higher levels of PM2.5 and CO compared with burning the same fuels at lower altitudes. Finally, the need to survive cold weather has led to a tradition of well-insulated homes.
In 2008, we began collaborating with nomads and farmers in Qinghai to design a high- performance solar cooker. Participating villagers had used solar cookers before but previous designs did not meet their power, portability, durability, and safety expectations. Cooks liked parabolic solar cooker designs because they provided high power output, essential to meeting cook-time expectations. These designs, however, were uncomfortable to use. Cooks had to lean into the front in order to stir food, exposing their eyes to painful levels of concentrated UV radiation and partially blocking solar input to the cooker in the process. Cooks found the sundials used to align parabolic solar cookers confusing. In some cases, solar cookers set fire to people’s sleeves or homes. In other cases, women from migratory families had attempted to carry 95kg concrete solar cookers on their backs and still bore the scars from the experience. Many solar cookers lasted mere months before losing their intended functionality and becoming the tops of doghouses or the gates for sheep pens.
A variety of solar concentrators have been developed to perform stovetop, oven, and specialty cooking operations.5 The application of these technologies, however, has been limited due to performance, awareness, pricing, accessibility, regulatory, and cultural factors.6,7
In South Africa, Wentzel and Pouris (2007) found that the most significant barriers to the adoption of solar cookers were poor quality, high price, and low retail availability coupled with low awareness amongst the population.8 Kimambo’s 2007 study of solar cookers in Sub Saharan Africa further highlighted the need for more appropriate designs coupled with affordable prices.9 Similarly, Mirza et al. (2003) described the need for better-suited technologies, awareness building, end-user financing, and more robust distribution channels for solar cookers as being crucial to Pakistan’s energy policy.10
Previous studies indicate that prior energy interventions in rural China failed to reduce indoor particle pollution below the Chinese national standards.11, 12 This underscores the continued need for new interventions that better meet rural energy needs while also reducing emissions. In addition, it supports the need for thorough evaluation of new interventions to ascertain whether they meet their social and environmental goals prior to widespread implementation.
In this study we worked with nomadic communities to develop an energy technology better suited to their needs and to evaluate the impact of that intervention under real use conditions in two nomadic communities in Qinghai, China.
Summary/Accomplishments (Outputs/Outcomes):
Development
Guided by user criteria and testing feedback, we designed 54 different solar cooker prototypes over a six-year period from 2008-2013 (Figure 2, left). The result is a portable, durable, and ergonomic solar cooker called SolSource capable of rapid energy input to the pot (Figure 2, right).
Figure 2. (Left) selection from among the 54 prototypes of solar cookers developed and tested with study communities. (Right) Final design of SolSource entering the market.
These designs sought to meet the following set of key user-defined performance criteria provided by collaborating villagers regarding their expectations of new cooking technologies (Table 1). Control, ease of use, safety, load stability, and cleanliness were accomplished primarily via the design of the cooker while palate, cook- times, durability and quality were also largely affected by the materials employed.
Perfomance Criteria | Description |
Palate | Good appearance, flavor, and tecture of the food. |
Control | Cook must feel in control of the outcome of the cooking. |
Cook-time | Stir-fry within minutes. Boil 3-4L if water in <1 hour. Cook for at least 7 hours per day. |
Ease of Use | Easy to set up and operate. No special training or written manuals required. Intuitive and enjoyable to cook on. |
Safety | No glare to cook's eyes. No risk of unwanted fires. Safe for children to be around. No danter of tipping when stirring the pot. No need to hold cold metal parts during winter. |
Load 7 Stability | Must hold at lest 15kg of food and withstand high wind speeds. |
Portability | Must weigh <50kg and disassemble into a pack that can be carried by a single person or a yak. |
Durability | Last for at lest five years. |
Quality | Product should make owners proud by sing high-quality materials and workmanship and by performing well. |
Cleanliness | Stove must be easy to clean and should not damage pots. |
Table 1. Performance Criteria
By removing a section of the back of the parabolic dish, we created an interface where cooks can stand to interact with the food (“user interface” in Figure 3a). This user interface enables cooks to stir the pot from behind the solar cooker, keeping their eyes away from harmful radiation and creating an ergonomic cooking position. The dimensions of the user interface comfortably accommodate people taller than 1.6m in height, which represents the lower 25th percentile of rural women’s height in Qinghai, China.13
We added a solar alignment aid to support manual solar tracking (Figure 3a). Rather than using a sundial, we created a hazed mirror that shows users a reflection of the focal point on the bottom of the pot so cooks can have full confidence that the device is properly aligned. The experimental solar cooker has an altitude rotation range from 5° to 65° and an azimuth rotation range of 360°, available in 7.5° increments (Figure 3b).
Figure 3a Figure 3b
Development of a suitable reflector material was key to the performance of the system. The four common types of solar cooker reflectors available on the market—mirrors, aluminized polyethylene terephthalate (PET), pressed sheet aluminum, and silverized polymers— face challenges related to weight, cost, durability, and formability. Mirrors are heavy and fragile.
PET degrades rapidly with UV exposure and abrasion. Pressed sheet aluminum dents and scratches easily or else is costly if a thicker material is used. Silverized polymers are costly and anti-rust treatments stiffen them such that they cannot be formed in the three-dimensional geometries most efficient at concentrating solar energy.
We developed, tested, and began employing a 3D formable, low-cost, lightweight material that achieves >90% specular reflectivity when virgin resin is used (Figure 4). Ten years of accelerated weathering led to <1% loss in reflectivity and seven years of accelerated abrasion testing reduced gloss by ~5% (Table 2).
Figure 4. Three dimensionally formable reflector with >90% specular reflectivity when analyzed with Filmentrics F20-FXR following ASTM-E971. Reference solar spectra from NREL (ASTM G173-03) show global average altitude adjusted spectral irradiance
After 10 years of accelerated weathering | |
Performance Parameter | Change |
Reflectivity Loss | - <1% |
Yellowness Increase | + <10% |
Haze Increase | +~5% |
After 7 years of accelerated abrasion | |
Performance Parameter | Change |
Gloss Decrease | - ~5% |
DOI Increase | - <1% |
Table 2. Change in reflector performance parameters over ten years of accelerated weathering (ASTM-D4587-11, ASTM-D1925) and seven years of accelerated abrasion testing (ASTM- D523-08). Evaluations conducted with Rhopoimt IQ 20°/60° Goniophotometer.
During the development of these materials, we considered environmental impact as one of the key design drivers and used Sustainable Minds Life Cycle Assessment software to evaluate material and process environmental performance. The final SolSource design produces 4.21 kg of CO2 during raw materials
processing, manufacturing, transport, and end-of-life (Table 3). Each SolSource unit has the potential to prevent up to 4,000 times that amount from entering the atmosphere during its operational lifetime. By comparison, a photovoltaic of comparable power output produces ~600x more CO2 over its lifecycle and prevents 6-13 kg of CO2 for every kg that it produces. 14
Life Cycle Assessment | SolSource | Photovoltaic |
---|---|---|
Carbon dioxide emissions (kg) produced from extraction of raw materials, manufacturing, transport, and end-of-life | 4.21* | 2,550 - 3,600* |
Carbon dioxide emissions (kg) prevented during product use | 20,000 (rural China) | 15,491 - 48,000 (US Scenario) |
Positive Climate Impact Factor | 4,751** | 6-13 |
* SolSource produces 600x less CO2 compared with photovoltaics ** SolSource abates 4,000 times more CO2 than it produces |
Adoption
Following five years of development and testing, we conducted a market test by selling SolSource in nomadic, agricultural, and semi-urban communities in Qinghai, Province. During the three- month test period, nearly 1,000 SolSources were purchased at 800 RMB each (130 USD).
Follow-up studies were conducted in 8% of purchasing households to evaluate the perceived usefulness of SolSource to users and the pain points experienced by users in adopting the technology.
The main pain points centered on willingness to get the product dirty and fear of failure. Users were reluctant to take the protective plastic covering off the panels for fear of scratching them. Users did not intuitively understand the relationship between power output and removing the protective cover and this required instruction. Further, families habitually washed the stove after use and not before out of a desire to keep it in a shiny condition. The consequence of this was that, during sand storm season, people cooked with sand covering the reflector. Although this decreased the power output, people were still satisfied with performance. Users were delighted when shown the increase in performance if dust was removed prior to cooking. Fear of failure is discussed below.
We observed gender-based differences in people’s approach to new technologies within our study population. In general, a man’s role in the family focuses on the social, religious, political, and financial wellbeing of the family; while a woman’s role focuses on the Earthly needs of the family for: water, fuel, food, child bearing and rearing, and caring for the home. Men and women’s approach to new technology appeared to mirror these family roles. Main decision drivers for men included: perception of value, monetary opportunity, and status elevation. Main decision drivers among women focused around their confidence in cooking on the experimental solar cooker, time- efficiency, and cleanliness. Families purchased the experimental solar cooker when the man decided to do so, but families only incorporated the solar cooker into their daily routines when both the husband and wife had an interest in doing so.
Men appreciated the potential for the experimental solar cooker to save and generate money for the family. Many of the first families to adopt the experimental solar cooker were previously unable to access sufficient traditional fuel to feed their families, heat their homes, and feed their animals. They saw the experimental solar cooker as a way to meet energy needs that they were unable to meet previously.
Subsequent adopters were driven by a combination of meeting deprived energy needs, saving time or money by reducing fuel usage, and experimenting with a new technology that they felt would elevate their status in their communities. In cases where families used electric cooking stoves, the experimental solar cooker saved as much as 70% of the family’s fuel expenditures. Other families believed that the experimental solar cooker saved them fuel and money but did not know how to quantify these savings. Some families used the experimental solar cooker to make food or tea to sell as a business.
Men reported that family members, passersby, and traveling traders asked to buy their solar cookers from them or inquired where to buy one. Several of them purchased more solar cookers to resell in their communities. Men felt that the experimental solar cooker elevated their family’s social status in the community and represented a high-value purchase. Several study participants mentioned that positioning products as desirable items, as opposed to poverty alleviation handouts, was critical to the adoption of the experimental solar cooker.
Women interacted with the experimental solar cooker differently. In addition to being the primary cooks, women are also the primary fuel collectors, water collectors, and caretakers of the home.
Their busy schedules leave little room for experimentation. Women also tend to be more cautious towards new technologies, especially when they could affect how well they perform their roles within the family. Women preferred to use methods they knew would work rather than failing at a new method when doing so could leave their children hungry. Providing training for first adopter cooks helped build their confidence with using the experimental solar cooker.
Unlike fuel collection, which is a solitary endeavor, water collection is a social activity for women in our study communities. Once a few cooks in a village began using the experimental solar cooker, women discussed the experimental solar cooker while collecting water together. This led to an organic uptake of the experimental solar cooker amongst the village women as each new cook added their learning to the collective knowledge. This underscores both the importance of training first adopter cooks and of word of mouth as a valuable awareness-building tool.
Cooks who used the experimental solar cooker felt that boiling, steaming, and frying operations were easily controlled and resulted in tasty food. Several cooks preferred the stir-fried foods prepared on the experimental solar cooker compared with those prepared on a traditional stove. Others reported that meats dried out more quickly when cooking them on the experimental solar cooker. Teaching cooks to keep the lid on the pot while cooking meats solved this.
Because the experimental solar cooker can be used to cook a wide range of traditional foods, users felt that the experimental solar cooker could replace the bulk of the work of the indoor cooking stove and the outdoor cooking stove. They also felt they could use it to remove peak fuel consumption of the indoor cooking-heating stove by replacing the cooking functionality of that stove, but they still preferred to stoke the heating stove before bed on winter evenings in order to heat up the bed platform before sleeping.
Cooks got mixed results when exploring the use of the experimental solar cooker to replace open grass fires for baking bread. Some cooks reported that they burnt the bread they baked on the experimental solar cooker. The traditional grass fire method involves a relatively quick peak heat to all sides of the pot followed by residual smoldering and heat retention by the cast iron pot.
Based on this heating profile, we suggested removing the pot from the experimental solar cooker after approximately 20 minutes of heating, insulating it, and allowing the rest of the baking to occur with retained heat alone. This method is successful, but takes practice to perfect.
The experimental solar cooker can be used whenever the cook can see the shadow of the cooker. It cannot be used at nighttime or when the clouds are so dense as to prevent shadows from being visible on the ground. When asked whether this was a deterrent against using solar cookers, one participant explained that, if wood was the cheapest fuel but it was too wet to use, she would use another fuel until she could go back to using wood again. Similarly, cloudy days would not deter her from using solar energy because, when it was available, it was cheaper and more convenient. Usage of a range of different fuels and stoves is the norm in study homes.
User’s Return on Investment
The experimental solar cooker brings direct financial benefit to its owners and benefits society by improving the health of the workforce, decreasing deforestation, and decreasing carbon emissions. Health benefits in particular are large and difficult to quantify in monetary terms. Here we calculate the direct financial savings of the owner and the climate change benefits of the experimental solar cooker to approximate User’s Return on Investment for the experimental solar cooker. Actual return on investment to the user and to society exceeds what it is possible for us to quantify here.
Owners of the experimental solar cooker in rural China reported saving $15-$50 per month in avoided fuel and fuel-transportation costs, allowing them to payback the cost of the product in 3-9 months. This indicates that, not only are users able to earn back the initial cost of the product within as little as 3-months, but that—during its lifetime—the product also saves them up to 21 times the amount they spent to purchase.
In addition to the value directly returned to the owner, the experimental solar cooker also reduces carbon emissions. US EPA social cost of carbon models indicate that every dollar spent on the experimental solar cooker prevents $5 worth of future climate change related damage.
When considering the direct financial benefit and the climate change benefit, the overall return on investment for this product is $11-$26 for every dollar spent, and could be twice as much if the product remains in use for the full ten years examined in accelerated weathering tests (Table 4).
Paypack Period | 3-9 Months |
---|---|
User Return on Investment | $11-$26 for every $1 invested in SolSource |
Conclusions:
Collaborative User Design
It has been a long-standing concern whether solar cookers are able to provide the temperatures, cook-times, and durability expected by users at an affordable price. Our research has shown that a satisfactory solar cooking technology can be developed for a particular user group through long- term collaborative efforts. Cooks were able to use the experimental solar cooker to prepare the full range of local cuisine and were satisfied with the cook-times and available hours for cooking. Accelerated weathering and abrasion testing demonstrated a 10-year durability with minimal decline in performance. We have also shown that owners can earn back the cost of the product within as little as 3 months of purchase and that the technology can provide overall returns of up to 26 times the cost of the initial purchase.
Adoption and Implementation
Rural interest in solar energy was primarily motivated out of cost and convenience considerations, whereas urban interest was primarily motivated out of cost and environmental considerations.
We observed that meeting the adoption criteria of both male and female heads of households was key to the purchase and adoption of the experimental solar cooker.
Quality and Pricing
An important paradigm among development practitioners is the idea that products should be priced as low as possible in order to reach the lowest-income families. Our research indicates that developing high quality and relatively higher priced products that serve the needs of rising populations traditionally excluded from mainstream commercial markets may be an important driver of sustainable development alongside minimal product pricing.
Participants in our study were eager to participate in the development of products that better fit their lifestyle. They expected the same (or higher) quality and performance from those products compared with criteria we’ve experienced among members of more mainstream market segments.
Participants were willing to purchase expensive items that they felt would benefit their family in the long-term; whereas they were unwilling to purchase cheap items that brought little value.
Pricing high-quality products low raised suspicions in people’s minds and engendered less pride over ownership. The perception that the experimental solar cooker was high quality and modern was key to people’s interest in it. Its location in the front of the home, further positioned it as a status-elevating product.
Product positioning was a critical factor in the perception of value. A number of participants in our study were previous recipients of solar cookers through development aid programs. They felt embarrassed to have these technologies prominently featured in front of their homes because they felt it demeaned them in the eyes of their neighbors. In contrast, when these families saw respected members of their communities purchasing the experimental solar cooker, they felt more comfortable purchasing it. They were thankful for the fuel savings and proud to have it in front of their homes where they could tell passersby about it. This pride over ownership played an important role both in people’s adoption of the product into daily routines and in word of mouth advertising about the product.
User financing options may help low-income families access beneficial products without letting others know that they relied on an outside party to provide it for them. Financial education may be equally important. We observed a number of families making high value purchases without regard for long-term maintenance. One such example is a family who purchased a car without calculating the funds needed to purchase gas for the car. The family had to abandon the car during the migration season (for which it was purchased) because it did not have enough gasoline to last through the migration. This behavior seemed most common among subsistence families who had less interaction with or confidence in the cash economy.
Behavior Change
Another important paradigm in development is to design products and services that affect minimal behavior change among the target population. We argue that people’s desire for positive life-style transformation may be an important driver of development.
Participants were accustomed to self-sufficiency. In the past, they produced their own food, built their homes and stoves, and collected all the land-resources they needed. Although people now earn cash during the agrarian off-season, they prefer to use this cash on items that differ greatly from what they are already able to make themselves, especially when these products increase the status of their family, make their tasks more convenient, or provide enjoyment. Examples of products that participants categorized in this light include: cell phones, televisions, refrigerators, and cars; all of which are associated with marked behavioral change.
Throughout our 7-year collaboration, villagers repeatedly highlighted the importance of convenience, status, and enjoyment in their technology purchasing and usage decisions. In addition to satisfaction on basic performance criteria, people perceived the final design of the experimental solar cooker as high quality and aesthetic, with a convenient and enjoyable user experience. Participants found the option of a modern-looking cooking technology combined with zero recurring fuel costs to be an attractive product offering.
We observed that Haier, the most respected local housewares brand in rural China, provides follow-up visits to their customers to help them with installment and train them on the operation of new products. Similarly, we found that providing follow-up calls and house visits to purchasers of the experimental solar cooker helped users surmount barriers to setting up and using the technology. Following this initial customer service interaction, we found that internal dialogue amongst village women appeared to be the strongest long-term driver of adoption of the experimental solar cooker.
Unwillingness to cook outdoors and the constraint of cooking when the sun is shining have been considered barriers to the adoption of solar cooking in the past. Since people in our study communities were already accustomed to cooking outdoors, this was not a barrier to adoption of the experimental solar cooker in our region. Participants saw inability to use solar cooking at nighttime or during rainy days as similar to the inability to use wet wood to make a fire and were not deterred from using solar energy as a result. When the sun was good, people wanted to rely on their solar cooker to perform well. When the sun was bad, they used another fuel until the sun became available again.
Applications to Other Locations
Although retailers in South Africa and the US have already expressed commercial interest in this technology, adoption in regions beyond western China remains for future observation.
Environmental conditions and local cultural practices vary with location. This experimental solar cooker was designed for use from the equator to 40°N or S and to operate effectively in both tropical and Himalayan environments. This technology is intended for use in direct sunlight and should not be used at night, indoors, in the shade, or on days with heavy cloud cover. We recommend that the adoption criteria be met in new regions where this experimental solar cooker is implemented, or else that appropriate local criteria be developed.
Precautions When Using
This experimental solar cooker can reach 350°C within minutes. The same precautions should be taken when cooking on this technology as with cooking on a traditional stove or gas grill. Although the reflector does not get hot, the burner is hot and people should avoid placing any body part or flammable object directly on or beneath the burner. The experimental solar cooker should be covered when not in use to prevent unwanted fires, or else integrated with our add-on modules.
Next Steps
Several technical advances are key to broadening and deepening the applications of solar cooking technologies globally. These include the development of:
- Robust and reliable temperature adjustment methods, both automated and manual
- Robust and reliable solar tracking and programmable temperature systems
- Affordable cookware optimized for solar cooking and solar-thermal storage
- High-performance, thermal storage systems in the operating range of 200-500°C for household and community use
References:
1 Energy and the World. World Bank. 2011. http://go.worldbank.org/DBVC9D4K20
2 New Study Estimates 4 million deaths from household cooking smoke each year. Global Alliance for Clean Cookstoves. December 13, 2012. http://www.cleancookstoves.org/media-and-events/press/new-study-estimates-4-million-from-household-cooking- smoke-each-year.html
3 China: Country Profile of Burden of Disease. World Health Organization. 2009. http://www.who.int/entity/quantifying_ehimpacts/national/countryprofile/china.pdf
4 Smoke: the Killer in the Kitchen. Practical Action. 2004. http://practicalaction.org/smoke-report-2
5 Panwar, NL. Kaushik, SC. Kothari, S. State of the art of solar cooking: An overview. Renewable and Sustainable Energy Reviews 16 (2012) 3776-3785.
6 Abdul Quadir, S. Mathur, S. Chandra Kandpal, T. Barriers to dissemination of renewable energy technologies for cooking. Energy Conv. and Manag. 36 (1995) 12: 1129-1132.
7 Tucker, M. Can solar cooking save the forests? Ecol. Econ. 31 (1999) 77-89.
8 Wentzel, M. Pouris, A. The development impact of solar cookers: A review of solar cooking impact research in South Africa. OpenUP. July 2007.
9 Kimambo, CZM. Development and performance testing of solar cookers. J of Energy in Southern Africa. 18 (2007) 3: 41-51.
10 Mirza et al. Status and outlook of solar energy use in Pakistan. Renew. And Sustain. Energy Rev. 7 (2003) 501-514.
11 Sinton, J. Smith, KR. Peabody, J. Yaping, L. Xiliang, Z. Edwards, R. Quan G. An assessment of programs to promote improved household stoves in China. Energy for Sustainable Development 8 (2004) 3: 33-52.
12 Edwards, RD. Liu Y. He G. Yin Z. Sinton J. Peabody J. Smith KR. Household CO and PM measured as part of a review of China’s National Improved Stove Program. Indoor Air 17 (2007) 3:189-2003.
13 China National Bureau of Statistics. Anthropometric Data. 2005.
14 Life Cycle Greenhouse Gas Emissions from Solar Photovoltaics. US NREL. November 2012.
Supplemental Keywords:
solar energy, impact evaluation, intervention study, China energy, China air quality, Qinghai, Tibetan Plateau, cookstove, solar cooker, randomized controlled trial, Himalayas, nomad, dung fuel, biomass, alternative energy, improved cookstove, household air pollution, indoor air pollution, clean energyProgress and Final Reports:
Original AbstractP3 Phase I:
The SolSource 3-in-1: A Comprehensive Decentralized Solar Energy Platform | Final ReportThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.