Cost-Benefit Analysis Methods For Assessing Air Pollution Control Programs in Urban Environments --- A Review

The most common method of evaluating beneficial impacts of environmental policies is cost-benefit analysis (CBA). In the present review, CBA methods for air pollution impacts are reviewed. Three types of air pollution effects are identified, including health, productivity, and amenity. Market valuation, stated preference methods, and revealed preference methods are identified for valuing benefits. Three types of costs are described, including private sector costs, societal costs, and governmental regulatory costs. A benefits valuation approach based on Freeman’s principals is described. A costs valuation approach based on U.S. Environmental Protection Agency and Dixon et al. principals is described. Limitations associated with estimates of benefits and costs are summarized. Input assumptions and results are compared for several existing air pollution control analyses. The importance of CBA in environmental policy studies is discussed. Our conceptual approaches should be useful in analyses of urban air pollution impacts and air pollution prevention policies.

The Effects of Ginkgo Biloba Extract(GBe)on Axonal Transport, Microvasculature and Morphology of Sciatic Nerve in Streptozotocin-induced Diabetic Rats

To evaluate the protective effects of Ginkgo biloba extract (GBe) which has antioxidant activity against peripheral neuropathy due to diabetes mellitus, slow axonal transport and morphology of sciatic nerve including endoneurial microvessels were examined in 12 rats with diabetes mellitus induced by streptozotocin (STZ, 60mg/kg, b.w., i.p.). Six of the diabetic rats were treated with 0.1% of GBe for 6 weeks from one week after the STZ injection. Serum glucose and lipid peroxide levels in GBe−treated diabetic rats were significantly lower than those in untreated diabetic rats (p<0.01, respectively), though the serum glucose level was higher than that in the control rats. L−[35S] methionine pulse radiolabeling with subsequent gel fluorography demonstrated that mean velocities (Vmean) of actin and β−tubulin, i.e. slow component b(SCb) transport in untreated diabetic rats were significantly lower than those in control rats (p<0.05, respectively); mean diameter of axons in the former rats was significantly smaller than that in the latter (p<0.01). Vmean of actin transport in GBe−treated diabetic rats was significantly faster than that in untreated diabetic rats (p<0.05). Vmean of slow axonal transport was significantly correlated with mean diameter of axons in the three groups of rats combined (p<0.01). On electron microscopy, severe altered endoneurial microvessels decreasing in luminal area together with endothelial cell degeneration or hypertrophy, pericyte debris and basement membrane thickening were observed in untreated diabetic rats; on the other hand these findings were less prominent in the diabetic rats treated with GBe. It is suggested that GBe treatment may protect disturbed slow axonal transport and pathological alterations of peripheral nerve with abnormal endoneurial microvasculature from diabetes mellitus by antioxidant activity.