Residential biofuels in South Asia: carbonaceous aerosol emissions and climate impacts.

High concentrations of pollution particles, including "soot" or black carbon, exist over the Indian Ocean, but their sources and geographical origins are not well understood. We measured emissions from the combustion of biofuels, used widely in south Asia for cooking, and found that large amounts of carbonaceous aerosols are emitted per kilogram of fuel burnt. We calculate that biofuel combustion is the largest source of black carbon emissions in India, and we suggest that its control is central to climate change mitigation in the south Asian region.

Factors related to the use of bone densitometry: survey responses of 494 primary care physicians in New England.

Large population-based surveys have shown that approximately 30% of people over age 65 years have osteoporosis and that 17% of the population over 65 years will sustain a fracture during their lifetime. Many people with osteoporosis are never being evaluated even though effective treatments are available. We examined why primary care physicians order few bone mineral density scans. We conducted a cross-sectional survey of primary care physicians practicing in any of the six New England states. Target physician specialties included internal medicine, general practitioners/family physicians, and obstetrician-gynecologists who had a facsimile number listed with the American Medical Association. Demographics, practice characteristics, use of bone densitometry, and attitudes regarding osteoporosis, bone densitometry and health maintenance were assessed by questionnaire. Twelve percent (n=494) of the physicians responded to the questionnaire. Respondents were similar to non-respondents with respect to years of practice, training and geographical state, though they were more likely to be female (p < or =0.05). Respondents had a mean age of 51 years, and 51% were trained in internal medicine, 25% in general practice/family practice and 24% in obstetrics-gynecology. The mean number of self-reported bone densitometry referrals per month was 10+/-11, and 25% of respondents reported that they referred fewer than 4 patients per month. In adjusted logistic models, factors significantly associated with referring fewer than 4 patients per month were: training in internal medicine (odds ratio (OR) 2.0, 95% confidence interval (CI) 1.0-3.9) or general practice/family practice (OR 2.6, 95% CI 1.3-5.2) versus obstetrics-gynecology; practicing in an urban setting (OR 2.5, 95% CI 1.3-4.9) or rural/small town setting (OR 2.2, 95% CI 1.2-4.1) versus a suburban setting; spending less than 50% of professional time in patient care (OR 4.0, 95% CI 1.7-9.5); seeing the lowest proportion of postmenopausal women (OR 2.5., 95% CI 1.2-5.3); the belief that calcium and vitamin D are adequate to treat osteoporosis (OR 2.1, 95% CI 1.0-4.5); and the belief that osteoporosis treatment should not be based on bone density results (OR 3.2, 95% CI 1.7-6.1). Potentially modifiable physician beliefs and a number of practice characteristics are associated with low referral rates for bone densitometry. Educational strategies aimed at improving the use of bone density testing should consider these factors.

Desorptivity versus chemical reactivity of polycyclic aromatic hydrocarbons (PAHs) in atmospheric aerosols collected on quartz fiber filters.

Nine polycyclic aromatic hydrocarbons (PAHs) contained in air samples collected on quartz fiber filters inside an urban tunnel and in a nearby mixed commercial residential area in the city of Rio de Janeiro, Brazil, were exposed to scrubbed air (to measure desorption loss) and to particle-free ambient air (to measure chemical reaction losses in the absence of desorption). The exposures were conducted for 5.5 to 9 hour periods at ambient temperature (22-26 degrees C) at face velocities typical of high volume sampling. Under prevailing atmospheric conditions all nine PAHs experienced filter losses which (for most of them) followed first order kinetics. For the ambient samples, in a 6 hour exposure period, the following five PAHs showed filter losses (% in parantheses) attributed exclusively to chemical reaction: benzo(b)fluoranthene (43), benzo(k)fluoranthene (39), benzo(a)pyrene (70), benzo(ghi)perylene (44), and indeno (1,2,3-cd)pyrene (41). The other four showed the following unassigned losses: pyrene (100), fluoranthene (65), crysene (72), and benzo(a)anthracene (71). The results are discussed in the light of possible filter artifacts in PAH sampling and the use of PAH profile signatures for source identification of atmospheric particulate matter in receptor modeling.