Indoor Air Monitoring

Experts have long been monitoring the levels of air pollution in our towns and cities and there is now a growing amount of evidence which suggests that indoor air monitoring is also necessary. Some studies show that the air in our homes is even more polluted than that outside of it – in addition to this many of us spend more time at home than we do outside it. Thus we are exposed to a great deal of air pollution for a good part of our daily lives. It makes sense if we are at home so much to do something about monitoring the quality of the air we are breathing – particularly if there are family members who suffer from allergies such as asthma.

In many buildings, and particularly our homes, there is not as much ventilation as there should be. This means that there is not enough air from outside coming in – which means harmful particles remain in the atmosphere rather than being removed via cross currents of air. Often, the very products that we use to clean our homes add to the level of pollutants already there. Detergents, disinfectants and air freshening sprays all add to the chemicals that we are breathing. Small wonder that an increasing number of people are investing in indoor air monitoring systems.

An indoor air quality or IAQ monitor generally has three sensors which detect the presence of carbon monoxide, carbon dioxide and oxygen gases. When oxygen is consumed it produces a current which is proportionate to the concentration of gas that is in the air. Oxygen is detected by means of an electric or fuel based sensor. Because the sensor is directly exposed to oxygen on a consistent basis it has an expected life of between eighteen months and two years.

The other two gases, carbon monoxide and carbon dioxide are detected through an electrochemical sensor, much like the oxygen sensor – and infrared detection sensor respectively. The electrochemical sensor absorbs very small amounts of gas and this, along with the electric output is controlled by a diffusion barrier. Infrared sensors operate via the transmission of infrared beams through carbon dioxide. The amount of beam energy absorbed is directly related to the amount of carbon dioxide in the air. The sensor then detects how much of the infrared beam’s energy is left after passing through the gas and converting it to a reading of how much carbon dioxide there is in the air.