WTC monitoring scope update, July 2002

NYC 9/11 Public Portal Document

a. Based on consultation with resident or owner, aggressive or modified aggressive air sampling will be conducted. Residents shall not be present in their apartment during aggressive air sampling activities.

We do not see the benefit or need to -U_s_c a leaf blower to_ aggitate the ind-oor enyironroent to this extent during sampling. An electric leafblower is capable ofproducting air velocities of 155 to 210 mph according to Scars. These air velocities are far removed from any air velocities that occurinindoor environments. (And, yes, you can reduce the air velocities from a leafblower to some extend, but what is thepoint?') We understand tihatsuchatec^quewaS-Used in mmCTs’eabins in Montana but this isless than pursuasive given the differences between those indoor environments and those ofoccupied apartments in Manhatten, Why would we dp_this?_ What is the benefit? We are not aware ofany expert on indoor air quality who has used or would advocate die use_ ofsuch high air velocities. In addition, the fact that we propose that the resident or owner decide whether to use iive (leafhlower)pr tnodified aggressive sampling protocols sjiggeste that the aggressive protQcpl is not goro or key to our study. Moreover, it will add another stratification to our study and reduce our power to- interpret the study results. There is also the potential to damage furnishings in the dwellings throng theuse ofthis technique. It will only take a fey highly publicized incidence to tarnish our whol effort. We recommend that we do not propose the use offiip aggressive sampling protocoj,

1. Before beginning-aggressi veair SdUlpmu;g, forced air equipment (such as a 1 horsepowerelectric leafblower) shalFbe used todircctexhaust air against walls, ceilings, floors and other surfaces. \^Qicn directing flic exhaust, caution shall be taken to mimimzc disturbance and potential damage to hxrnislnngs and pc];rsonal beiongaigs: hr For modified aggressive air sampling forced an equipment shall not be employed. The terminology used here is incorrect and confusing because a 20-in fan is a form of forced air equipment. iii. All other procedures arc identical for aggiessivc and modified aggiessive air sampiittg: b. One 20-inch fan shall be installed per 10,000 cubic feet of room space and run at low speed. The fen shall operate continuously throughout sampling and shall not be turned off until sampling is completed. How long before sampling should the fan be turned on? This. is an unportant issue because we want to sample at or near_^eady state and the air moved by the fan has a time constant the will partially determine how long it wll take to achieve steady state. At a minimum.-the time prior tQ_ sampling when the fanjshould be turn on should be specified.. c. For studio apartments 3 air samples shall be collected. For 1 -bedroom apartments and above 5 air samples shall be collected. Sampling equipment shall be placed in living areas and away from obstructions. The sampling cassette must be placed on a tripod directed downward at .a 45. degree angle and not taped to existing surfaces. d. Common spaces will be sampled without flic use offorced air devices (fens, leafblowcrs etc): For small spaces, less than 160 square feet, 3 air samples will be collected. For large

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