6 conditions is a result from gases, microbial contaminants or particulates which is a
factor of the IAQ level. From here, we knew that IAQ represent the condition of a building which indicates either it is healthy or not. According to ASHRAE 2009, by
implementing air in occupied spaces with a concentrations that is not at a harmful level and no conditions that can affect the occupants health and comfort and gives
dissatisfaction, we can gain good IAQ. Both indoor air pollution levels and thermal environmental parameters should be included in the considerations.
Indoor air quality IAQ is said to be effected by indoor air environment IAE which mainly established by the thermal environment, wet environment and air quality Yang
2012. Thus, to study more on IAQ and its factors and effects, we also should study on indoor air environment. ASHRAE 2009 indicates that those aspects of human
health and diseases that are resulted by causes in the IAE is included in indoor environmental health. Occupational health which relates to workplace airborne
contaminants is the area which is defined clearly of indoor environmental health. In the IAE, contaminants that is observed giving problems comprise allergens, tobacco
smoke, radon, and formaldehyde. Even though air is composed mainly of gases, air contaminants can be divided into two class which is either particles or gases.
2.2.1 Factors affecting IAQ in a building
There are many factors that affect IAQ in a building. According to ASHRAE 2009, air borne contaminants which can affect the level of IAQ may be transported from the
outdoor or discharged indoors by many factors. Based on Industry Code of Practice on Indoor Air Quality, ICOP IAQ 2010, there are six sources of poor IAQ in a building
listed which are the occupant of the building, inadequate materials used for the construction of the building, the activities performed in the building, high and
inadequate use of normal products, combustion gases, and poor ventilation.
One of the factors that contributes to poor level of IAQ is the occupants themselves. As we already know, we exhaled carbon dioxide when we are breathing. Other than
that, our body also released human VOCs such as human skin flakes. According to
7 Mohamed and Sulaiman 2011, in dust particulates or humid environment which
consist of human skin flakes and other dead or decaying biological materials, it is typically found the nutrients which are need by the microbes to grow. Thus, both of
carbon dioxide and human VOCs are pollutants which influence the level of IAQ of a building Wang and Zhang 2010. Also, in a study by Karina and Maria 2010, they
have proved that the present of occupants in air conditioned indoor environment had significant impact on the temperature inside a room. Which as stated earlier,
temperature is one of the factor which includes in IAQ factor as it can be related with affecting discomfort as it is too high or low. This is also supported from a study by
Jang Yeul and Wan Je 2009 that the duration of a buildings occupancy affect the concentrations of the IAQ pollutants most.
Besides the occupants themselves influenced the level of IAQ in a building, the activities done in a building also contributes as an IAQ factor. There are many
activities that we did in a buildings which affects the IAQ level. For an example when we clean our carpet, we might as released the dust particles which is a pollutant into
the air thus it affect our comfort and health which directly affect the IAQ in the building. This theory is supported by Marzuki et al., 2010 that in their research, they
have concluded that one of the important factor that influence the indoor concentrations pollutants is the surrounding human activities. Although some of our
activities with the objective of making indoor environment healthier, often they also decreases our air quality. For an example, carbon monoxide particles and dust is
emitted into the air as we used gas burner for cooking or lighting a fireplace. Sunyoung et al., 2013, Duflo et al. 2008. This is also proved by a research by Isabelle
et al. 2000, which concluded there are many complex mixtures of gases and particles that are emitted by combustion that contaminated indoor and outdoor air.
Another factor that contributes to the IAQ status in a building is the environment of the building itself. For an example, a building located in a industrial location would
tend to have more pollutants in the outdoor air which might be absorbed into the building by the ventilation, occupants or much more. According to Christopher 2001,
the status of pollutants in the indoor environment is either brought in from outdoor air or emitted from indoor sources. When there are not enough outdoor air is brought in
8 to dilute the pollutants or to carry the pollutant out of the building, the concentrations
of the air pollutants will increase USDHHS 2006. Another research which have similar finding by Jang Yeul and Wan Je 2009 that is there are many factors that
affect the level of IAQ in a building, including the environmental factors i.e., temperature, humidity, the amount of ventilation, and the air flow speed, the location
of the building, and the pollutant origins. Environment of the room should also be taken into the consideration such the temperature of the room, glare from the lights
and much more. According to Po et al., 2001, their research found that the occupants of the building is experiencing some poor indoor air quality symptoms due to lower
temperature than recommended by the guidelines and also glare problems.
The level of IAQ is also affected by the contamination levels in the building. In a research by Gunnar and Peder 2001, they have stated that it can be generally assumed
that an increase of indoor air complaints is caused by indoor air pollution one way or another. We can say that indoor air pollution will always result to bad IAQ. Indoor air
pollution can be caused by many factor. Gases or particles released into the air from a wide variety of sources Sunyoung et al., 2013. As stated by Yau et al., 2012, indoor
air pollutants or inadequate ventilation may be the cause of IAQ problems. Without proper ventilation, the level of contamination would rise thus resulting in poor IAQ.
Jang Yeul and Wan Je 2009 supported this theory in their study by stating that IAQ level will decrease with the decrease in ventilation performance because of revised
airtightness in buildings and the increasing usage of materials and furniture that accommodate high level of contaminations in the building. Lastly, according to John
and Vina 1998, IAQ level is degraded as there were cross contamination between ventilation and the inlets for the outdoor air which is contaminated because the IAQ
level depends on the external air which is used for the ventilation.
2.2.2 Effects of poor IAQ in a building
