General Indoor Air Quality Test

Indoor air quality testing or monitoring can be conducted in relation to many different potential contaminants. However the most common and standard indoor environment comfort indicators are:

Carbon Dioxide

Carbon Monoxide

Temperature

Relative Humidity

All of these parameters can be tested for using the same meter and instantaneous results can be obtained without any lab analyses required. The meter utilised is also capable of data logging all the results at a given time interval. In other words a reading can be taken for each parameter every 30 seconds or minute for example. These readings are usually printed out after the consultation and it is then possible to analyse the results and determine when readings increase and decrease. The Building Biologist will make detailed notes of the location of every logged measurement so that it would be simple to determine when and where indoor air quality parameters increased and decreased.

Carbon Dioxide levels tend to become elevated in areas in which there is not enough ventilation. This problem can become worse as more people are located in a smaller area with little or no ventilation and fresh air exchange. This often occurs in meeting rooms and in buildings where the ventilation and fresh air exchange is generally not sufficient. As human beings we exhale Carbon Dioxide ( CO2 ) and this is why the concentration of CO2 increases when more people are present in one area. This is often the reason for fatigue and drowsiness in lecture and conference rooms. Many office buildings depend entirely on their HVAC (heating, ventilating and air conditioning) units as there are no openable / operable windows. This is where problems often arise as HVAC systems are generally costly and are therefore not readily replaced and in many cases not readily serviced either. Increased Carbon Dioxide levels will give rise to fatigue and a lack of concentration. This means that productivity will decrease and staff will not be comfortable in their work environment. This can also cause an increase in illness as the general well being of individuals is compromised.

The average level of naturally occuring carbon dioxide in the air is roughly 400ppm (parts per million). While most sources will say that carbon dioxide levels only become a problem at 1000ppm and above it is interesting to note that studies have found that fatigue can set in at 700ppm.

Carbon Monoxide is colourless and odourless and is created from the combustion of carbon containing fuels like petrol and gas. Motor vehicle emissions, gas heaters, gas stoves and cigarette smoke are just some sources of carbon monoxide. At low concentration levels it can cause headaches, nausea, disorientation and fatigue. It is important to note that foetuses, infants and the elderly are most susceptible to carbon monoxide exposure. When gas appliances are not operating correctly they can emit higher levels of carbon monoxide. It is also important to consider the location of vehicles in a home or workplace setting. It has been found that buildings close to busy roads, car parks located close to workspaces and garages adjoining bedrooms can potentially create problems with regards to carbon monoxide exposure. Prevailing winds and building design are important considerations in these types of cases.

The average level of naturally occuring carbon monoxide in the air is roughly 0.2ppm and it can become a problem when the levels are around 9ppm.

Temperature is a very subjective indoor air quality parameter as the idea of an ideal temperature varies dramatically amongst individuals. It is interesting to note that the ideal comfortable temperature 50 years ago was around 17 Degrees Celsius. However today that temperature would most often be regarded as cold and the ideal temperature now is closer to 21 Degrees Celsius. An individuals ideal temperature depends on many factors including genetic predisposition, disease state, pregnancy, clothing, level of activity and seasonal changes. In summer an ideal temperature would be between 22 - 24 Degrees Celsius and in winter between 20 - 22 Degrees Celsius. It is important that the difference between the indoor and outdoor temperature be kept as small as practically possible. Large variations between indoor and outdoor temperatures can increase the risk of adverse health effects.

It is very common to find that areas in which temperatures are elevated are often the areas in which individuals complain of feeling uncomfortable and experiencing fatigue and headaches. This also goes hand in hand with relative humidity which is discussed next.

Relative Humidity is one of the best indicators of indoor air quality and comfort. Ideal indoor humidity levels are between 45 - 55%. Anything below 40% (low humidity) is regarded as dry and may lead to symptoms such as dry eyes, nose and throat, increases respiratory illness and static electric shocks. Relative humidity levels above 60% (high humidity) are regarded as humid and can give rise to stuffiness, mould problems, headaches and fatigue. Evaporative coolers often cause increased humidity when there is not sufficient ventilation. In many cases the occupants are unaware that windows need to be open when this type of cooling is being used. When relative humidity levels rise our tolerance for higher temperatures drop. Building materials that are capable of controlling moisture (like concrete and breathable timber) can assist in controlling excessive relative humidity levels. Just think of the timber used in a sauna. If relative humidity levels are persistently high the risk of mould problems will increase and this in turn will cause adverse health effects.

This is why it is critical that a Building Biologist inspect and assess the building design and materials as well as conduct the indoor air quality monitoring. The understanding of the biology of a building enables the Building Biologist to understand what may be the cause of the elevated indoor air quality pollutants. This will in turn make it easier to provide recommendations to resolve any problems.