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# Pollution Concentration in Rooms

## Concentration of a pollution in a limited space as a room depends on the amount of polluted material spread in the room, supply of fresh air, outlets positions and construction, principles used for supply and outlet from the space.

The concentration of a pollution in a limited space as a room, container, tank etc. depends on

• amount of polluted material spread in the room or space
• amount of fresh supply air or fluid
• the outlet positions and constructions
• the principles used for supply and outlet from the space
• fluid flow in the space

The generic equation for pollution concentration (amount of polluting product to amount of fluid in space (like air a room)) can be calculated

c = q / n V (1 - e-nt) + (c1 - c2) e-nt + c2                                      (1)

where

c = concentration in the space (or in the room) at perfect mix (m3/m3) (kg/kg)

q = amount of pollution added to the space (m3/h) (kg/h)

n = volume changes per hour (h-1)

V = volume or mass of the space (m3) (kg)

e = the number 2.72..

t = time (h)

c1 = concentration in the space at start (m3/m3) (kg/kg)

c2 = concentration in the supply fluid (m3/m3) (kg/kg)

If the start concentration (t = 0) of the space and the concentration in the supply fluid is zero, equation (1) can be reduced to

c = q / n V (1 - e-nt)                                   (2)

Note! After some time the concentration in the room will stabilize. The table below shows the value of c when the amount of pollution q = 1, and the volume of the space V = 1.

For full table - rotate the screen!

Pollution Concentration in Rooms
Volume changes per hour
(1/h)
Concentration of pollution - c - (m3/m3) (kg/kg)
Time - t - (min)
1020408016032064012802560
0.5 0.1599 0.3070 0.5669 0.9732 1.4728 1.8610 1.9903 2.0000 2.0000
1 0.1535 0.2835 0.4866 0.7364 0.9305 0.9952 1.0000 1.0000 1.0000
2 0.1417 0.2433 0.3682 0.4653 0.4976 0.5000 0.5000 0.5000 0.5000
4 0.1216 0.1841 0.2326 0.2488 0.2500 0.2500 0.2500 0.2500 0.2500
8 0.0921 0.1163 0.1244 0.1250 0.1250 0.1250 0.1250 0.1250 0.1250
16 0.0582 0.0622 0.0625 0.0625 0.0625 0.0625 0.0625 0.0625 0.0625
32 0.0311 0.0312 0.0312 0.0313 0.0313 0.0313 0.0313 0.0313 0.0313
64 0.0156 0.0156 0.0156 0.0156 0.0156 0.0156 0.0156 0.0156 0.0156

## Related Topics

• ### Ventilation

Systems for ventilation and air handling - air change rates, ducts and pressure drops, charts and diagrams and more.

## Related Documents

• ### Air Change Rates in typical Rooms and Buildings

Fresh air (make up air) rquirements - or recommended air change rates (ACH) for typical rooms and buildings like auditoriums, kitchens, churches and more.
• ### Air Contaminants - Exposure Limits

Exposure limits for various air contaminants.
• ### Air Intakes and Outlets

Ventilation systems - air intakes and outlets - rules of thumbs.
• ### Carbon Dioxide Concentration in Rooms Occupied with People

Carbon dioxide concentration in a room may indicate air quality and ventilation system efficiency.
• ### Design of Ventilation Systems

Design procedure for ventilation systems - air flow rates, heat and cooling loads, air shifts according occupants, air supply principles.
• ### Gases Solved in Water - Diffusion Coefficients

Diffusion flux [kg/m2s] tells how fast a substanse solved in another substance flows due to concentration gradients. Diffusion constants [m2/s] for several gases in water.
• ### Outdoor Supply Air Rates

Recommended supply air rates of outdoor air - with or without smoking - in rooms like banks, assembly halls, hotels and many more.

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## Citation

• The Engineering ToolBox (2003). Pollution Concentration in Rooms. [online] Available at: https://www.engineeringtoolbox.com/room-polution-concentration-d_120.html [Accessed Day Month Year].

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12.8.9