signs); and, show the Premises to prospective purchasers, current or prospective investors, Mortgagees, ground lessees or insurers, or, during the last twelve (12) months of the Term (or following any Event of Default), prospective tenants. If reasonably necessary, Landlord may temporarily close all or a portion of the Premises to perform repairs, alterations and additions. However, except in emergencies, Landlord will not close the Premises if the work can reasonably be completed on weekends and after normal business hours. Entry by Landlord shall not constitute a constructive eviction or entitle Tenant to an abatement or reduction of Rent. Notwithstanding anything to the contrary in this Lease, except in the event of an emergency, neither Landlord nor any Landlord’s agents, employees or contractors shall access the labs or clean rooms within the Premises (collectively, the “Labs”) without being accompanied by a representative of Tenant; provided however, that Tenant shall (a) provide Landlord with prior written notice of the location of such Labs, and (b) make a representative of Tenant available to Landlord during regular business hours within twenty-four (24) hours after written request therefor (and in the event that Tenant fails to make such representative available within such 24-hour period, Landlord shall be permitted to access the Labs without the presence of a representative of Tenant).
15.ENVIRONMENTAL MATTERS.
15.1Hazardous Materials. Tenant shall not cause nor permit, nor allow any of Tenant's or Tenant’s affiliates’ employees, agents, customers, visitors, invitees, licensees, contractors, assignees or subtenants (individually, a “Tenant Party” and collectively, “Tenant's Parties”) to cause or permit, any Hazardous Materials (as defined herein) to be brought upon, stored, manufactured, generated, blended, handled, recycled, treated, disposed or used on, under or about the Premises, the Building, the Common Area, Property or the Project, except for (a) routine office and janitorial supplies in usual and customary quantities stored, used and disposed of in accordance with all applicable Environmental Laws, and (b) subject to the terms and conditions of Section 15.6 below, commercially reasonable amounts of Permitted Hazardous Materials (as hereinafter defined) in the ordinary course of Tenant’s business to the extent consistent with the Permitted Use and stored, used and disposed of in accordance with all applicable Environmental Laws. Tenant agrees, if requested by Landlord to deliver copies of all Material Safety Data Sheets prepared by manufactures, importers or suppliers of any chemicals. Tenant shall not install, operate or maintain any above or below grade tank, sump, pit, pond, lagoon or other storage or treatment vessel or device on the Property without Landlord’s prior written consent which may be withheld in Landlord’s sole discretion. As used herein, the term “Environmental Laws” means all applicable present and future statutes, regulations, ordinances, rules, codes, judgments, orders or other similar enactments of any governmental authority or agency regulating or relating to health, safety, or environmental conditions on, under, or about the Premises or the environment, including without limitation, the following: the Comprehensive Environmental Response, Compensation and Liability Act; the Resource Conservation and Recovery Act; and all state and local counterparts thereto, and any regulations or policies promulgated or issued thereunder. The term “Hazardous Materials” means and includes any substance, material, waste, pollutant, or contaminant listed or defined as hazardous or toxic, under any Environmental Laws, asbestos and petroleum, including crude oil or any fraction thereof, natural gas liquids, liquefied natural gas, or synthetic gas usable for fuel (or mixtures of natural gas and such synthetic gas) and explosives, flammables, or radioactive substances of any kind. As defined in Environmental Laws, Tenant is and shall be deemed to be the “operator” of Tenant's “facility” and the “owner” of all Hazardous Materials brought on the Premises by Tenant, its agents, employees, contractors or invitees, and the wastes, by-products, or residues generated, resulting, or produced therefrom. Tenant and Tenant's Parties shall comply with all Environmental Laws and to the extent of Tenant’s actual knowledge, promptly notify Landlord in writing of the violation of any Environmental Law or presence of any Hazardous Materials (other than Permitted Hazardous Materials in compliance with Section 15.6) and office and janitorial supplies as permitted above, in, on, under or about the Premises or the improvements or the soil or groundwater thereunder. Tenant shall neither create or suffer to exist, nor permit any Tenant Party to create or suffer to exist any lien, security interest or other charge or encumbrance of any kind with respect to the Property, including without