The word negative is always associated with something bad or the lack of something good. It is the opposite of the word positive.
In the world of minimizing contact with harmful airborne contaminants the word negative is often used in conjunction with negative air pressure, or making a specific room or area negative.
Hospitals have rooms where they isolate a patient that has a highly communicable disease where the air in the room is constantly being filtered through a HEPA based air filtration system and air handler. The pressure in the room is slightly lower than the air outside the room so when the door to the room is opened all the air moves into the room thus keeping any airborne pathogens from escaping the room.
Negative pressure rooms are common at the CDC in Atlanta and in R&D labs around the world where highly toxic or corrosive chemicals and materials are used for product development. These rooms use both HEPA and Carbon or other adsorptive materials to remove airborne particulate as well as gaseous pollutants.
Pure Air Systems, based in Indianapolis, Indiana manufactures high end, commercial grade HEPA and Carbon based, fan-powered air filtration systems which are used in many of these negative room applications. Their systems can move from 50 CFM up to 2,000 CFM of air through the scanned HEPA filters where in many cases the units themselves are the only air moving device creating the negative pressure.
These systems can also be attached to or be part of the air handling units working in conjunction with cooling and heating systems.
In many instances homes can be under negative pressure when the HVAC system is not properly balanced making the home slightly negative which in this case is bad. That means every time the air handler fan comes on the house tends to draw some air in from the outside which means you are bringing in warm, moist or cold air all the time. Getting your HVAC systems balanced is recommended.
For more information on the complete line of HEPA and Carbon based air filtration systems please go to our website at: http://www.pureairsystems.com or call us on our toll-free number at: 800-869-8025.