Source-to-receptor pathways of anthropogenic PM2.5 in Detroit,Michigan: Comparison of two inhalation exposure studies

Recent studies have attributed toxic effects of ambient fine particulate matter (aerodynamic diameter ≤ 2.5 μm; PM_2.5) to physical and/or chemical properties rather than total mass. However, identifying specific components or sources of a complex mixture of ambient PM_2.5 that are responsible for adverse health effects is still challenging. In order to improve our understanding of source-to-receptor pathways for ambient PM_2.5 (links between sources of ambient PM_2.5 and measures of biologically relevant dose), integrated inhalation toxicology studies using animal models and concentrated air particles (CAPs) were completed in southwest Detroit, a community where the pediatric asthma rate is more than twice the national average. Ambient PM_2.5 was concentrated with a Harvard fine particle concentrator housed in AirCARE1, a mobile air research laboratory which facilitates inhalation exposure studies in real-world settings. Detailed characterizations of ambient PM_2.5 and CAPs, identification of major emission sources of PM_2.5, and quantification of trace elements in the lung tissues of laboratory rats that were exposed to CAPs for two distinct 3-day exposure periods were completed.This paper describes the physical/chemical properties and sources of PM_2.5, pulmonary metal concentrations and meteorology from two different 3-day exposure periods—both conducted at the southwest Detroit location in July 2003—which resulted in disparate biological effects. More specifically, during one of the exposure periods, ambient PM_2.5-derived trace metals were recovered from lung tissues of CAPs-exposed animals, and these metals were linked to local combustion point sources in southwest Detroit via receptor modeling and meteorology; whereas in the other exposure period, no such trace metals were observed. By comparing these two disparate results, this investigation was able to define possible links between PM_2.5 emitted from refineries and incinerators and biologically relevant dose, which in turn may be associated with observed health effects.     

Changes in Arthropod Assemblages along a Wide Gradient of Disturbance in Gabon

Abstract: Searching for indicator taxa representative of diverse assemblages, such as arthropods, is an important objective of many conservation studies. We evaluated the impacts of a wide gradient of disturbance in Gabon on a range of arthropod assemblages representing different feeding guilds. We examined 4 × 10⁵ arthropod individuals from which 21 focal taxa were separated into 1534 morphospecies. Replication included the understory of 3 sites in each of 4 different stages of forest succession and land use (i.e., habitats) after logging (old and young forests, savanna, and gardens). We used 3 complementary sampling methods to survey sites throughout the year. Overall differences in arthropod abundance and diversity were greatest between forest and open habitats, and cleared forest invaded by savanna had the lowest abundance and diversity. The magnitude of faunal differences was much smaller between old and young forests. When considered at this local scale, anthropogenic modification of habitats did not result in a monotonous decline of diversity because many herbivore pests and their associated predators and parasitoids were abundant and diverse in gardens, where plant productivity was kept artificially high year‐round through watering and crop rotation. We used a variety of response variables to measure the strength of correlations across survey locations among focal taxa. These could be ranked as follows in terms of decreasing number of significant correlations: species turnover > abundance > observed species richness > estimated species richness > percentage of site‐specific species. The number of significant correlations was generally low and apparently unrelated to taxonomy or guild structure. Our results emphasize the value of reporting species turnover in conservation studies, as opposed to simply measuring species richness, and that the search for indicator taxa is elusive in the tropics. One promising alternative might be to consider “predictor sets” of a small number of taxa representative of different functional groups, as identified in our study.     

Creating and validating GIS measures of urban design for health research

Studies relating urban design to health have been impeded by the unfeasibility of conducting field observations across large areas and the lack of validated objective measures of urban design. This study describes measures for five dimensions of urban design - imageability, enclosure, human scale, transparency, and complexity - created using public geographic information systems (GIS) data from the US Census and city and state government. GIS measures were validated for a sample of 588 New York City block faces using a well-documented field observation protocol. Correlations between GIS and observed measures ranged from 0.28 to 0.89. Results show valid urban design measures can be constructed from digital sources.     

Biofuels production in developing countries: assessing tradeoffs in welfare and food security

In light of the recent rise in global food prices, much of the literature on crop-based biofuel production focuses on the potential impacts on food security. Studies have identified linkages between the usage of feedstocks in biofuel production and international food price increases. In addition, these studies indicate that food prices are expected to continue to rise over the next decade in response to biofuel consumption targets adopted in the U.S. and E.U. Despite these indications, some countries for whom food security and poverty reduction are still an issue have initiated crop-based biofuel development and set forth national blending targets for energy use within the transportation sector. As a result, a broader examination of the tradeoffs concerning welfare and food security related to biofuel development merit consideration. Opportunities to generate income and expand agricultural production technology through biofuel development may provide welfare gains that can improve purchasing power and decrease vulnerability to price shocks for food and energy. In addition, biofuel production schemes that promote alternative energy sources for household uses can improve productivity and health, especially for women and children. To assist with the sector development that maximizes welfare gains, we suggest a number of key indicators that might be useful in constructing a typology that can be applied across countries to characterize their energy needs and better target the types of bioenergy uses that might be best suited for them. In addition, biofuel production models are reviewed and best-practices identified that can expand welfare gains for smallholders and the poor. Through these examples, we demonstrate a basis upon which policymakers might approach the prioritization of their national strategies towards developing renewable energy sources, such that they can have the maximum impact upon important goals of human welfare and development.     

Trends in Public Attitudes Toward Air Pollution

This paper attempts to bring together the findings relative to people’s attitudes about air pollution from a series of studies conducted by or for the U. S. Public Health Service. Trends are noted. These findings are presented in the light of planning for the implementation of air pollution abatement measures and probable public reactions to them. Further research needs are pointed out. Special emphasis is placed on the control officer’s needs for this type of information, its derivation, and its possible use in programming.