Editing Smoke testing (mechanical) (section)

=== Infectious disease control ===
[[File:Smoke generator.png|alt=A hand grasping a small blue apparatus with white smoke emerging from its top|thumb|upright|A smoke generator used to visualize air flow.  Smoke generators provide a low-cost method to visualize air flow patterns around [[Hierarchy of hazard controls|hazard control]] measures, including in and around [[Fume hood|fume hoods]] and pressure differences between adjacent areas or rooms.<ref name=":0">{{Cite journal|url=https://www.cdc.gov/niosh/docs/2014-102/default.html|title=Current Strategies for Engineering Controls in Nanomaterial Production and Downstream Handling Processes|date=November 2013|website=U.S. National Institute for Occupational Safety and Health|pages=9–20|access-date=2017-03-05|doi=10.26616/NIOSHPUB2014102|doi-access=free}} {{PD-inline}}</ref>]]
In [[infectious disease]] control a smoke test is done to see whether a room is under [[Negative room pressure|negative pressure]]. A tube containing smoke is held near the bottom of the negative pressure room door, about two inches in front of the door. The smoke tube is held parallel to the door, and a small amount of smoke is then generated by gently squeezing the bulb. Care is taken to release the smoke from the tube slowly to ensure the velocity of the smoke from the tube does not overpower the air velocity. If the room is at negative pressure, the smoke will travel under the door and into the room. If the room is not at negative pressure, the smoke will be blown outward or will stay stationary.