ABSTRACT
Environmental problems occur as a side-effect of other activities. Economists have emphasized that they are a case of negative externalities. If they are left unchecked this is because the losers are different from those whose activities create the problems. This is not always the case. Sometimes the problem is created by those who suffer from it. An important example is indoor air pollution, which is very widespread in poor countries and occurs as a result of cooking with low-quality stoves or open fires using traditional fuel like wood, charcoal or agricultural wastes. The problem is left unchecked because the victims do not have the resources or technology to deal with it, and perhaps also because they do not understand the extent of the harmful effects on their health.
