Carbon dioxide, indoor air concentrations

Posted on Październik 23, 2007

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limits carbon dioxide

Techniques for analyzing IAQ include collection of air samples, collection of samples on building surfaces and computer modelling of air flow inside buildings. The resulting samples can be analyzed for mold, bacteria, chemicals or other stressors. These investigations can lead to an understanding of the sources of the contaminants and ultimately to strategies for removing the unwanted elements from the air.


Carbon Dioxide

Pollution is the introduction of pollutants into the environment to such a point that its effects become harmful to human health.
Carbon dioxide is a surrogate for indoor pollutants emitted by humans and correlates with human metabolic activity. Carbon dioxide at levels that are unusually high indoors may cause occupants to grow drowsy, get headaches, or function at lower activity levels. Humans are the main indoor source of carbon dioxide. Indoor levels are an indicator of the adequacy of outdoor air ventilation relative to indoor occupant density and metabolic activity. To eliminate most Indoor Air Quality complaints, total indoor carbon dioxide should be reduced to below 600 ppm above outdoor levels. NIOSH considers that indoor air concentrations of carbon dioxide that exceed 1,000 ppm are a marker suggesting inadequate ventilation (1,000 ppm equals 0.1%). ASHRAE recommends that carbon dioxide levels not exceed 700 ppm above outdoor ambient levels. The UK standards for schools say that carbon dioxide in all teaching and learning spaces, when measured at seated head height and averaged over the whole day should not exceed 1,500 ppm. The whole day refers to normal school hours (i.e. 9.00am to 3.30pm) and includes unoccupied periods such as lunch breaks. Canadian standards limit carbon dioxide to 3500 ppm. OSHA limits carbon dioxide concentration in the workplace to 5,000 ppm for prolonged periods, and 35,000 ppm for 15 minutes.

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