Chemical reactivities of ambient air samples in three Southern California communities

The potential adverse health effects of PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) and vapor samples from three communities that neighbor railyards, Commerce (CM), Long Beach (LB), and San Bernardino (SB), were assessed by determination of chemical reactivities attributed to the induction of oxidative stress by air pollutants. The assays used were dithiothreitol (DTT)- and dihydrobenzoic acid (DHBA)-based procedures for prooxidant content and a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) assay for electrophiles. Prooxidants and electrophiles have been proposed as the reactive chemical species responsible for the induction of oxidative stress by air pollution mixtures. The PM_2.5 samples from CM and LB sites showed seasonal differences in reactivities, with higher levels in the winter, whereas the SB sample differences were reversed. The reactivities in the vapor samples were all very similar, except for the summer SB samples, which contained higher levels of both prooxidants and electrophiles. The results suggest that the observed reactivities reflect general geographical differences rather than direct effects of the railyards. Distributional differences in reactivities were also observed, with PM_2.5 fractions containing most of the prooxidants (74–81%) and the vapor phase most of the electrophiles (82–96%). The high levels of the vapor-phase electrophiles and their potential for adverse biological effects point out the importance of the vapor phase in assessing the potential health effects of ambient air.

Implications:?PM_2.5 and its corresponding vapor phase, containing semivolatile organics, were collected in three communities in the Los Angeles Basin and examined with toxicologically relevant chemical assays. The PM_2.5 phase contained most of the prooxidants and the vapor phase contained most of the electrophiles, whose content was highest in summer samples from a receptor site that reflected greater photochemical processing of the air parcel during its transport. As electrophiles initiate both adverse and adaptive responses to foreign substances by biological systems, their presence in the vapor phase emphasizes the importance of this phase in the overall health effects of ambient air.     

Sex segregation of work in Finland and the quality of women's work

The Finnish labor market is sharply segregated by sex. This is a statistically well-documented fact and holds true for all Western European market economies. The aim of this article was to find out whether women profit (regarding the quality of their work) from performing the same sort of work as men. The qualitative aspects of work were the following: autonomy at work; lack of routinization of work; the compulsory rhythm of work; and the demands for social skills. We also analyzed monthly pay and its variation according to functional segregation of work. The empirical data came from the Finnish Study on Working Conditions (1984) which is a representative sample of the Finnish wage-earning population with 4502 persons of whom 48 per cent were women and 52 per cent men. Our results indicate that women often profit from the fact that they perform the same sort of work as men. This profit was more apparent for white-collar than for blue-collar women. For men the effects of segregation on job characteristics were the opposite. They often profit from sex segregated work. Social status played a major role regarding the qualitative aspects of work.     

Environmental sustainability comparison of a hypothetical pneumatic waste collection system and a door-to-door system

Waste collection is one of the life cycle phases that influence the environmental sustainability of waste management. Pneumatic waste collection systems represent a new way of arranging waste collection in densely populated urban areas. However, limited information is available on the environmental impacts of this system. In this study, we compare the environmental sustainability of conventional door-to-door waste collection with its hypothetical pneumatic alternative. Furthermore, we analyse whether the size of the hypothetical pneumatic system, or the number of waste fractions included, have an impact on the results. Environmental loads are calculated for a hypothetical pneumatic waste collection system modelled on an existing dense urban area in Helsinki, Finland, and the results are compared to those of the prevailing, container-based, door-to-door waste collection system. The evaluation method used is the life-cycle inventory (LCI). In this study, we report the atmospheric emissions of greenhouse gases (GHG), SO(2) and NO(x). The results indicate that replacing the prevailing system with stationary pneumatic waste collection in an existing urban infrastructure would increase total air emissions. Locally, in the waste collection area, emissions would nonetheless diminish, as collection traffic decreases. While the electricity consumption of the hypothetical pneumatic system and the origin of electricity have a significant bearing on the results, emissions due to manufacturing the system's components prove decisive.     

Evolution of sex-specific pace-of-life syndromes: causes and consequences

Behavioral Ecology and Sociobiology - The success of social insect colonies is dependent upon efficient and dynamic allocation of resources to alternate queen and worker castes. The developmental...