; (2) in subparagraph (E) by striking the period at the end and inserting ; and ; and (3) by adding at the end the following: (F) to an airport operator of a congested airport (as defined in section 47175) and a unit of local government referred to in paragraph (1)(B) to carry out a project to mitigate noise, if the project— (i) consists of— (I) replacement windows, doors, and the installation of through-the-wall air-conditioning units; or (II) a contribution of the equivalent costs to be used for reconstruction, if reconstruction is the preferred local solution; (ii) is located at a school near the airport; and (iii) is included in a memorandum of agreement entered into before September 30, 2002, even if the airport has not met the requirements of part 150 of title 14, Code of Federal Regulations, and only if the financial limitations of the memorandum are applied. . 163. Lead emissions (a) Study The Secretary of Transportation shall enter into appropriate arrangements with the National Academies of Sciences, Engineering, and Medicine under which the National Research Council will conduct a study and develop a report on aviation gasoline. (b) Contents The study shall include an assessment of— (1) existing non-leaded fuel alternatives to the aviation gasoline used by piston-powered general aviation aircraft; (2) ambient Pb concentrations at and around airports where piston-powered general aviation aircraft are used