From an efficiency point of view, the regulation of conventional pollutants should take exposure into account—the more persons exposed to a given pollutant concentration, the larger is the damage caused by it and therefore the smaller is the efficient concentration level, all other things being equal. An alternative point of view, however, holds that this policy does not treat all citizens fairly. Rather, according to this viewpoint fairness requires that all citizens be protected by a uniform safe concentration threshold. What are the advantages and disadvantages of each approach? Which do you think represents the best approach? Why?