> higher [rates] when pollution was declining The above part sounds weird, but I suspect that it's supposed to illustrate the following part "to depress spendi

> higher [rates] when pollution was declining The above part sounds weird, but I suspect that it's supposed to illustrate the following part "to depress spending until the environment improved". In depressing spending until the environment improved, there would be higher rates while pollution declines and (I suspect) there would continue to be higher rates until an optimal level of pollution is reached.