Emission Performance and User Acceptance of a Catalytic Biomass Cookstove in Rural Guatemala.

A catalytic rocket stove was developed to reduce emissions and improve efficiency compared to open cooking fires or traditional semienclosed cookstoves, called poyos, typical of rural Guatemala. Traditional stoves often emit particulate matter and carbon monoxide at sufficient levels to cause respiratory illnesses and other health problems. Using focus group results, the stove was tailored to the needs of Guatemalan cooks. Field trial participants were provided with stove training to ensure that stoves were operated correctly. Somewhat surprisingly, the field trial demonstrated a high level of user acceptance in rural Guatemala, where users cooked 93% of the time with the catalytic stove despite having to change some cooking practices. In the field trial, the stove reduced emissions by as much as 68% and improved fuel efficiency by as much as 61% during real-world cooking events relative to the traditional poyo. An additional qualitative portion of the field study identified strengths and weaknesses of the stove that are being addressed as part of an iterative design process.

Small, Smart, Fast, and Cheap: Microchip-Based Sensors to Estimate Air Pollution Exposures in Rural Households.

Over the last 20 years, the Kirk R. Smith research group at the University of California Berkeley-in collaboration with Electronically Monitored Ecosystems, Berkeley Air Monitoring Group, and other academic institutions-has developed a suite of relatively inexpensive, rugged, battery-operated, microchip-based devices to quantify parameters related to household air pollution. These devices include two generations of particle monitors; data-logging temperature sensors to assess time of use of household energy devices; a time-activity monitoring system using ultrasound; and a CO2-based tracer-decay system to assess ventilation rates. Development of each system involved numerous iterations of custom hardware, software, and data processing and visualization routines along with both lab and field validation. The devices have been used in hundreds of studies globally and have greatly enhanced our understanding of heterogeneous household air pollution (HAP) concentrations and exposures and factors influencing them.

Observational Constraints on the Oxidation of NOx in the Upper Troposphere.

NOx (NOx ≡ NO + NO2) regulates O3 and HOx (HOx ≡ OH + HO2) concentrations in the upper troposphere. In the laboratory, it is difficult to measure rates and branching ratios of the chemical reactions affecting NOx at the low temperatures and pressures characteristic of the upper troposphere, making direct measurements in the atmosphere especially useful. We report quasi-Lagrangian observations of the chemical evolution of an air parcel following a lightning event that results in high NOx concentrations. These quasi-Lagrangian measurements obtained during the Deep Convective Clouds and Chemistry experiment are used to characterize the daytime rates for conversion of NOx to different peroxy nitrates, the sum of alkyl and multifunctional nitrates, and HNO3. We infer the following production rate constants [in (cm(3)/molecule)/s] at 225 K and 230 hPa: 7.2(±5.7) × 10(-12) (CH3O2NO2), 5.1(±3.1) × 10(-13) (HO2NO2), 1.3(±0.8) × 10(-11) (PAN), 7.3(±3.4) × 10(-12) (PPN), and 6.2(±2.9) × 10(-12) (HNO3). The HNO3 and HO2NO2 rates are ∼ 30-50% lower than currently recommended whereas the other rates are consistent with current recommendations to within ±30%. The analysis indicates that HNO3 production from the HO2 and NO reaction (if any) must be accompanied by a slower rate for the reaction of OH with NO2, keeping the total combined rate for the two processes at the rate reported for HNO3 production above.

Pyrogenic inputs of anthropogenic Pb and Hg to sediments of the Hood Canal, Washington, in the 20th century: source evidence from stable Pb isotopes and PAH signatures.

Combustion-derived PAHs and stable Pb isotopic signatures ((206)Pb/(207)Pb) in sedimentary records assisted in reconstructing the sources of atmospheric inputs of anthropogenic Pb and Hg to the Hood Canal, Washington. The sediment-focusing corrected peak fluxes of total Pb and Hg (1960-70s) demonstrate that the watershed of Hood Canal has received greater atmospheric inputs of these metals than its mostly rural land use would predict. The tight relationships between the Pb, Hg, and organic markers in the cores indicate that these metals are derived from industrial combustion emissions. Multiple lines of evidence point to the Asarco smelter, located in the Main Basin of Puget Sound, as the major emission source of these metals to the watershed of the Hood Canal. The evidence includes (1) similar PAH isomer ratios in sediment cores from the two basins, (2) the correlations between Pb, Hg, and Cu in sediments and previously studied environmental samples including particulate matter emitted from the Asarco smelter's main stack at the peak of production, and (3) Pb isotope ratios. The natural rate of recovery in Hood Canal since the 1970s, back to preindustrial metal concentrations, was linear and contrasts with recovery rates reported for the Main Basin which slowed post late 1980s.