1. Dust limits of outdoor environment
Of air cleaning technology, the most ordinary one is the counting concentration of dust grain with size of more than or equal to 0．5μm.
As for outdoor atmosphere dust concentration, the difference is great among difference regions, and statistics is made in 3 typical regions. Massive statistical data analysis obtains outdoor counting concentration of the 3 typical regions.
Industrial cities: the counting dust concentration is maximum 3X105 grains/L, and maximum amount is approximately 106 grains/L (serious pollution).
Suburb areas of cities (exclusive of suburb industrial parks): the counting dust concentration is no more than 2X105 grains/L;
Non-industrial areas or rural areas: the counting dust concentration is maximum 1X105 grains/L.
Massive researches show that, as for cleanness rooms with purification of level 100 and below for the efficient air cleaning system, when the atmosphere dust concentration varies within 106 grains/L, and the influences on dust concentration in the cleanness room are omitted. In purification design computation, 106 grains/L are taken as the outdoor atmosphere dust concentrations, and it is also insured in engineering.
2. Dust capacity of indoor unit volume
Dust capacity in the operation room includes persons and building surfaces, and equipment surface. Practice shows that, the persons’ dust capacity is dominant, and the persons’ behaviors have larger influences on dust capacity. Under general conditions, in the design computation: when persons are still: 105 grains/（P·min） average dust capacity when persons are active: 5x105 grains／（P·min） Floor surface grains: 1．25x104 grains／9min·m2） When persons are still: 2 Cleanness operation room layout. At present, purification of cleanness operation room in China include 4 levels :100, 1000, 10000 and 100000. Only a fewer operation rooms are given with more than level 100 and less than level 10000. Based on cleanness levels, the cleanness operation rooms are classified into one-way flow cleanness room, quasi-one-way cleanness room and turbulent flow cleanness room.