Final answer:
Permits issued after July 1st, 2008 are subject to environmental regulations that fall under the Clean Air Act amendments, which introduced marketable permits designed to reduce pollution emissions from power plants over time.
Step-by-step explanation:
Permits issued after July 1st, 2008 in the context provided are subject to environmental regulations based on the Clean Air Act. The Clean Air Act was amended in 1990 to address issues such as acid rain by reducing sulfur dioxide emissions from electric power plants.
Specifically, the amendment introduced a system of marketable permits, which are permits that can be bought and sold by firms and are designed to reduce total emissions over time. For example, a permit allowing the emission of a certain amount of pollution in one year could authorize less the following year.
This declining allowance system, sometimes referred to as "shrinkable" permits, was aimed at gradually reducing overall pollution levels. Furthermore, the final rule signed on October 1, 2015, and effective December 28, 2015, indicates that 2008 standards may remain in effect in some areas while a transition to the 2015 standards is being implemented.
Under this system, if the permits themselves are issued after July 1st, 2008, they would be subject to the evolving environmental standards and rules that have been implemented since then. This could include adjustments in the allowed pollution units year-on-year and adherence to both the 2008 and 2015 environmental standards until a complete transition has been made.