maxitfloor.com - Emissions

Emissions

It seems entirely logical that if something in a building is the cause of health problems for its occupants, one likely source is the air that people breathe inside the building. Indoor air can be affected by emissions from ventilation systems and office equipment, but also from building materials, etc.

With continuing interest in the indoor environment, the question of emissions from building materials has remained at the top of the agenda. Emissions from building materials can be of two kinds:

Primary Emissions	Emissions that can be said to be built into the material and released successively, normally at a decreasing rate. The emissions from casein-containing levelling compounds are typical primary emissions.
Secondary Emissions	Emissions that can occur as the result of reactions between different materials mixed together. Moisture often plays an important role in this. A typical secondary emission is 2-ethylhexanol that can occur when PVC flooring is adhered to a moist, highly alkaline substrate such as concrete.

Building material and emissions

Most building materials produce emissions to a greater or lesser extent. One significant group of emissions are VOCs (volatile organic compounds). These are added together to give the TVOC (total volatile organic compounds). For building materials with a large surface area, the rate of emission is normally given as µg/m2 *hour. Since the VOC can be made up of thousands of different chemical compounds, the amount of each compound should be normalised. This is done using so- called toluene equivalents. This means that the emission of each compound is calculated as if it was toluene.

Since TVOC can be made up of thousands of different compounds, it is obvious that there cannot be any direct relation between the amount of TVOC and the extent of health problems. A high TVOC can consist of totally harmless compounds in high amounts. On the other hand, a low TVOC can be made up of compounds harmful even in very low dosages. A low TVOC is therefore no guarantee of good indoor air quality. Because of this, TVOC measurements identify compounds present in the highest concentrations, that can be checked for any known health hazards.

However there are emissions that are significant despite the fact that they do not show up at all in the TVOC measurements. They come from compounds that have an odour at extremely small concentrations – below the detection limit of the VOC equipment. Odours that people do not like – bad smells – are the most important, since a bad smell indicates that here is something to avoid. In order to cope with smelly emissions, there are different techniques using test panels of people that can be skilled or non-skilled.