An Australian stocks and flows model for asbestos.

All available data on asbestos consumption in Australia were collated in order to determine the most common asbestos-containing materials remaining in the built environment. The proportion of asbestos contained within each material and the types of products these materials are most commonly found in was also determined. The lifetime of these asbestos containing products was estimated in order to develop a model that projects stocks and flows of asbestos products in Australia through to the year 2100. The model is based on a Weibull distribution and was built in an excel spreadsheet to make it user-friendly and accessible. The nature of the products under consideration means both their asbestos content and lifetime parameters are highly variable, and so for each of these a high and low estimate is presented along with the estimate used in the model. The user is able to vary the parameters in the model as better data become available.

Unit pricing of household garbage in Melbourne: improving welfare, reducing garbage, or neither?

Charging for household garbage collection per unit of waste is becoming more popular. Discussions in the practical literature focus on unit pricing as a way to encourage diversion to recycling and reduction in waste, but the economics literature emphasizes welfare maximization through charging at the marginal social cost. In the present study unit pricing was examined from both perspectives through a case study on unit pricing by volume in Melbourne, Australia, using longitudinal data. The marginal social cost per unit weight was estimated using a custom costing model and a valuation of environmental externalities. This cost was applied to a derived regression equation for change in waste quantities with unit price. The results suggest a very weak link between marginal pricing and change in garbage quantities, with an arc elasticity of demand at the margin of -0.02. Small reductions in garbage may have been achieved by local governments that overtly used pricing systems to this end. Enforced reduction of standard bin sizes had much more impact on waste quantities and did not lead to any significant management or political problems.