; and (C) the proximity of the chemical facility to large population centers. (2) List The Secretary shall maintain a list of covered chemical facilities that the Secretary designates under subparagraph (A). (3) Submission of information In making a determination whether to designate a chemical facility as a covered chemical facility under paragraph (1), the Secretary may require the submission of information from an owner or operator of a chemical facility with respect to the quantities of substances of concern that the owner or operator possesses or plans to possess. (c) Assignment of Covered Chemical Facilities to Risk-Based Tiers (1) Assignment The Secretary shall assign each covered chemical facility to 1 of 4 risk-based tiers, as established by the Secretary, with tier 1 representing the highest degree of risk and tier 4 representing the lowest degree of risk. (2) Provision of information The owner or operator of a covered chemical facility shall provide, at the request of the Secretary, any information in addition to information required by the Secretary under subsection (b)(3) that may be necessary for the Secretary to assign the chemical facility to the appropriate tier under paragraph (1). (3) Notification (A) In general Not later than 60 days after the date on which the Secretary determines that a chemical facility is a covered chemical facility or is no longer a covered chemical facility or changes the tier assignment of a covered chemical facility under paragraph (1), the Secretary shall notify the owner or operator of the chemical facility of the determination or change. (B) Required information A notification made by the Secretary under subparagraph (A) shall include— (i) the reason for the determination or change described in subparagraph (A)