Pollution is a by-product of human activity. It occurs when the environment becomes scarce—when dumping garbage imposes a cost. There are benefits as well as costs to pollution; the efficient quantity of pollution occurs where the difference between total benefits and total costs is maximized. This solution is achieved where the marginal benefit of additional pollution equals the marginal cost. We have seen that an alternative approach shows that efficiency is also achieved where the marginal benefit of pollution abatement equals the marginal cost of abatement.
Economists measure the benefits of pollution in terms of the costs of not dumping the pollution. The same curve can be read from left to right as the marginal benefit curve for emissions and from right to left as the marginal cost curve for abatement.
The costs of pollution are measured in two ways. One is through direct surveys. Respondents can be asked how much compensation they would be willing to accept in exchange for a reduction in environmental pollution; alternatively, they can be asked how much they would pay for an improvement in environmental quality. A second approach infers the marginal cost of increased pollution from other relationships. The effects of pollution on house prices or rental values, for example, allow economists to estimate the value people place on environmental quality. Pollution costs can also be estimated on the basis of the costs they impose on firms in production.
Three types of policies are available to reduce pollution. Moral suasion is sometimes used, but it is effective only under limited conditions. Command-and-control regulation is used most commonly, but it is likely to be inefficient. It also fails to provide incentives for technological change in the long run. The most promising policies are the incentive approaches, which include emissions taxes and marketable pollution permits. Both can be designed to reduce emissions at the lowest cost possible, and both create an incentive for firms to search out new and cheaper ways to reduce emissions.
Although public policy has stressed command-and-control methods in the past, pollution rights exchanges are now being introduced. Past policies may have been inefficient, but they have succeeded in improving air quality, at least in the nation’s cities.
Suppose the dry-cleaning industry is perfectly competitive. The process of dry cleaning generates emissions that pollute the air, and firms now emit this pollution at no cost. Suppose that the long run equilibrium price for dry cleaning a typical item is $5, and a pollution-control program increases the marginal cost by $1 per item.
Now suppose the dry-cleaning industry in the community is monopolistically competitive. Suppose the initial price per unit of dry-cleaning is $6. Suppose that a charge levied on dry-cleaning firms for the pollution they generate increases the cost of a unit of dry-cleaning by $1.
Suppose local government regulations allow only a single firm to provide dry-cleaning services to a local community, and this firm generates pollution as in Problem 1. The firm initially charges a price of $4 per item. Now a pollution-control program is imposed, increasing the firm’s marginal and average total costs by $1 per item.
Suppose the marginal benefit (MB) and marginal cost (MC) curves for emitting particulate matter are given by the following schedules, where E is the quantity of emissions per period. The marginal benefits and costs are measured at the quantities of emissions shown.
| E/period | MB | MC |
|---|---|---|
| 0 | $230 | $0 |
| 200 | 190 | 10 |
| 400 | 150 | 30 |
| 600 | 110 | 50 |
| 800 | 70 | 70 |
| 1,000 | 30 | 90 |
Now suppose that rising incomes increase marginal cost as follows:
| E/period | New MC |
|---|---|
| 0 | $0 |
| 200 | 30 |
| 400 | 70 |
| 600 | 110 |
| 800 | 150 |
| 1,000 | 190 |
