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A medical device that converts liquid medicines into an aerosol or mist that is then inhaled through a mask or mouthpiece. Often used to deliver asthma medications that open blocked airways.
An atom with more electrons than protons has a negative charge and is called a negative ion. Negative ions are produced by rain showers, waterfalls, etc. and are thought to have a positive impact on human health, particularly to balance an overabundance of positive ions in the indoor environment. This is an area of great controversy.
A condition where the pressure in a space is less than that in surrounding areas. In this case, if openings exist, air from surrounding areas will flow into the negatively pressurized space, thereby containing the air in the negatively pressurized area. This can be useful for containing harmful particles in a particular area, such as in Tuberculosis isolation.
This is the European Norm (EN) two-part test of HEPA filtration. The first part of the test determines which sized particles pass most easily through the HEPA filter media. And because filter efficiency is correlated to the speed at which the air passes through the filter this test is performed at actual use speeds of the vacuum cleaner or air purifier being tested. In other words, the filter is tested under the real world conditions it will operate in.
Once the "most penetrating particle size" (MPPS) has been determined the second part of the test is conducted by testing the HEPA filter against only particles of the most penetrating particle size for an absolutely worst case scenario.
HEPA filters that pass the EN 1822 test have passed the world's most stringent test for HEPA filtration.