Relative humidity
For a pleasant working environment, it is important to make sure relative humidity does not fall below 40%. When relative humidity is less than 40%, the risk of disease is increased. Generally, it can be stated that symptoms that are caused by dry air vary, but three main factors can be distinguished: static electricity, moisture stability and health effects.
Static electricity
Dry air can cause static electricity in an environment. Static electricity can be diminished by increasing the relative humidity of air. Machines in a machine park give off static electricity as a result of friction. When there are more machines present that are active during a longer period of time, more friction will take place and the risk of static electricity increases. This mainly occurs at dry machine elements. In computer rooms, there is also a static electricity risk. Most static electricity is caused at a relative humidity of between 30 and 35%.
Moisture stability
Moisture stability means the ability of a material or product to maintain a certain level of moisture, despite fluctuations of relative humidity in its environment. Most materials give off or take up moist. This can cause damage to a material or product. In many sectors –such as vegetables, fruits, flowers and granes- this process is irreversible. When relative humidity is too high, this can also cause problems for antiques, paintings, books, papers, etc. Most damage to older products is caused by air humidity fluctuation.
Health effects
As temperatures increase, relative humidity decreases. Dry air can cause health effects, such as dry nose and throat. This causes a higher susceptivity to pathogens such as viruses. When it is cold, a higher air humidity makes people believe it is warm. This causes the heater to be on less often.
It appears that the climate for bacterial growth is worst when relative humidity is between 40 and 60%. Viruses can survive least at a relative humidity of between 47 and 70%. For people, relative humidity is most pleasant between 40 and 60%. For people that suffer from allergies and astma, relative humidity must be between 45 and 55%.
High relative humidity can cause constriction.
Desirable relative humidity and temperature for each activity
Below, a table is shown that outlines ideal temperatures and relative humidity for each sector in a given situation. This table is derived from JDK air-handling.
Activity | Temperature (°C) | Relative humidity (%) | Activity | Temperature ( °C) | Relative humidity (%) |
Backery
|
Leather
|
1
| |||
Biscuits and cookies
|
16-18
|
50
|
Storage room
|
10-16
|
40-60
|
Fermentation
|
24-27
|
70-75
| |||
Flour storage room
|
18-27
|
50-65
|
Libraries and Museums
|
21-27
|
40-50
|
Bread cooler
|
21
|
60-70
| |||
Confectionery
|
24-27
|
65-70
|
Paper products
| ||
Mixing bread dough
|
24-27
|
40-50
|
Binding
|
21
|
50-65
|
Yeast storage room
|
0-7
|
60-75
|
Wrinkling
|
24
|
60-65
|
Printing office
|
24-27
|
45-55
| |||
Granes
|
Storage room
|
24-27
|
40-60
| ||
Packing
|
24-27
|
45-50
| |||
Textile
| |||||
Confectionery
|
Cotton processing
|
24-27
|
50-55
| ||
Chocolate sales
|
17-18
|
50-65
|
Cotton spinning
|
16-27
|
50-70
|
Storage room
|
16-20
|
50-65
|
Articficial silk spinning
|
20-24
|
85
|
Cotton weaving
|
27
|
56-60
| |||
Food industries
|
Wire torsie articficial silk
|
21
|
60
| ||
Apple storage room |
-1
|
75-85
|
Silk processing
|
24-27
|
65-70
|
Banana ripening
|
20
|
90-95
|
Wool refining
|
27-29
|
65-70
|
Banana storage room
|
16
|
85-90
|
Wool spinning
|
27-29
|
50-60
|
Citrus fruits storage room
|
16
|
85
|
Wool weaving
|
27-29
|
60
|
Eggs storage room
|
2-13
|
75-80
| |||
Granes storage room
|
16
|
30-45
| |||
Mushrooms storage room
|
0-2
|
80-85
|
Tabacco
| ||
Potatoes storage room
|
4-16
|
85-90
|
Sigars and sigarettes
|
21
|
55-65
|
Sugar
|
27
|
30
|
Processing and storage
|
24
|
70-75
|
Tomatoes storage room
|
1
|
85
|
Packing
|
32
|
88-95
|
Tomatoes riping room
|
21
|
85
| |||
Wood processing
| |||||
Hospitals
|
End products
|
18-21
|
35-40
| ||
Children’s ward
|
24
|
50-65
|
Fixing
|
24-24
|
40-50
|
Operation room
|
24
|
55
|
Processing
|
18-24
|
35-40
|
Hospital rooms
|
24
|
40-50
| |||
Conservatories
|
27
|
70-80
| |||
Painting companies
|
22-24
|
40-50
|
Read more: https://www.lenntech.com/calculators/humidity/relative-humidity.htm#ixzz6OmxBEjis
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