Table of Contents
Advertisement
CHAPTER 8
Filtering for Freshness
1. Necessity of Filters
Clean air is necessary for humans to live a comfortable and healthy life. Besides atmospheric pollution that has been
generated with the development of modern industries and the growth in the use of automobiles, air pollution in air-tight room
has progressed to the point where it adversely affects the human body, and is now a major problem.
Hay fever is now a symptom often seen in the spring and demands for preventing pollen from entering rooms are increasing.
2. Data Regarding Dust
The particle diameter of dust and applicable range of filters are shown in Table 1, and representative data regarding outdoor
air dust concentrations and indoor dust concentrations is shown in Table 2.
Table 1 Aerosol particle diameters and applicable ranges of various filters
Table 2 Major dust concentrations
Type
Outdoor air floating dust
concentration
Indoor dust concentration
Remarks:
1. The core diameter of outdoor air dust is said to be 2.1 µm, and the 11 types of dust (average diameter 2.0 µm) as set by
JIS Z8901 as performance test particles are employed.
2. Dust in office rooms is largely caused by smoking, and the core diameter is 0.72 µm. The 14 types of dust (average 0.8
µm) as set by JIS Z 8901 as performance test particles are employed.
3. The core diameter of dust generated in rooms where there is no smoking is approximately the same as outdoor air.
4. Smoking in general offices (as per Japan):
Percentage of smokers
Average number of cigarettes : Approx. 1/person·h (including non-smokers)
Smoking length of cigarette
Amount of dust generated by one cigarette : Approx. 10 mg/cigarette
86
Aerosol particle diameter (µm)
0.001
0.01
0.1 0.3
Solid
Fumes
particles
Fluid
particles
Clay
Oil fumes
Tobacco smoke
Major
Carbon black
particles
ZnO fumes
Sea salt
particles
Viruses
Atmospheric
Air filters
HEPA filter
Large city
Small city
Industrial districts
General office
Stores (product vending stores)
Applications with no tobacco smoke
: Approx. 70% (adult men)
: Approx. 4 cm
1
10
100
Dust
Mist
Sprays
Mud
Sand
Fry ashes
Coal dust
Cement
Pollen
Bacteria
Hair
dust
Medium to high efficiency filters
Fine dust, coarse
dust fillers
Reference data
1000
0.1 - 0.15 mg/m
0.1 mg/m
0.2 mg/m
10 mg/h per person
5 mg/h per person
5 mg/h per person
3
3
or less
3
or more
Advertisement
Table of Contents
