Here are some other examples in the pressure-state-response framework.
An environmental agency monitors the level of pollutants in
the air. A typical unit of measure is parts per million. An
environmental agency responds to that level of pollution by issuing
permits to facilities that are causing the pollution. However, it is
only recently that these agencies are looking at the pressures causing
the state: the amount of toxic material that is being used or released
into the environment.
Another example is a general measure of air quality: the number of
days that air quality is considered "good." Because air quality
problems come from automobiles, environmental agencies measure the
number of vehicles that have been inspected or the number that meet
certain emission standards. However, the pressure behind the problem
is the amount that people drive. The emission controls on cars over
the last two decades have dramatically decreased the amount of
pollution generated per gallon of gasoline used. However, because
people are driving much more than they used to, some metropolitan
areas have actually seen air quality get worse. If the pollution per
mile driven goes down by half but people are driving three times more
than they used to, the result is more pollution.
A third example is the problem of what to do with trash. It is not
uncommon to measure the amount of material that is landfilled or the
amount incinerated. Environmental agencies also count the number of
inspections done on incinerators or permits for landfills. However,
the pressure is the amount of product being purchased for which the
ultimate end is the landfill or incinerator.