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A4OM <br /> 2.2.1 QA/QC Sample Designation <br /> Sample duplicates will be labeled numerically and will not indicate the point from which the <br /> sample was collected. Times for all duplicate samples will be 12:00 on the day of sampling. <br /> 2.3 Sample Collection <br /> Prior to sampling, each canister will have its vacuum checked with a dedicated gauge, with <br /> the expected vacuum ranging from -28 to -29" Hg. If any canister differs from the others by <br /> 3" Hg or more, the canister will not be used as the integrity of the canister may have been <br /> compromised. <br /> Building conditions should reflect current occupancy conditions, including typical use of any <br /> HVAC system. The occupant will not make changes to the building envelope during <br /> sampling that could potentially alter results (i.e. leaving a window or door open). <br /> 1) The canister will be placed such that the inlet is at breathing height, between 3 ft and 5 ft <br /> above the floor. <br /> a) This height can be achieved using a stand or table, if available, or through attaching <br /> a short length of stainless-steel or Teflon tubing to the Summa®canister using <br /> stainless steel air-tight fitting and attached to the inlet of the tubing. <br /> b) The intake of the tubing will be located at approximately breathing height. <br /> 2) Both ambient air canisters and indoor air canisters will be set-up prior to opening the <br /> canister valves. <br /> 3) Once the canisters are in place, the valve of the indoor air canister will be opened, and <br /> the start time and vacuum gauge reading will be recorded. This process is repeated for <br /> each other canister as quickly as possible. <br /> 4) Each indoor air canister will be equipped with an 8-hour flow controller, for commercial <br /> non-residential buildings, or a 24-hour flow controller for residential buildings. After 8 or <br /> 24 hours and when the pressure is at approximately 5" Hg, the valve will be closed, and <br /> the final vacuum and time will be recorded. <br /> 2.4 Ambient Air Samples <br /> Ambient (i.e., outdoor) air samples are helpful to identify potential contributions to indoor air <br /> concentrations from building air exchange with outdoor air and will be collected any time <br /> indoor air samples are collected. <br /> • Locations for ambient air samples will include one upwind, one downwind, and one <br /> crosswind location. <br /> • Ambient air sampling will be conducted concurrently with indoor air sampling. Sample <br /> locations will be outside and adjacent to the targeted building. Per USEPA (2015), <br />