Impact of Indoor Air Quality Towards Workers’ Health Performance on Safety Engineering Perspective

Ahmad Shah Hizam bin Md Yasir (GS40361) andMohd Ruzaimi bin Mohd Ariffin (GS38824) | | |

Abstract
Deterioration of air quality in working environments has now become an increasing and critical in both developed and developing countries. The potential risks and problems related to indoor air pollution has been recognized, and there is a need to measure and establish air quality standards for those working in any confined environments. For health and safety reasons, the indoor air quality (IAQ) in an enclosed building, where a few people are working in it, was investigated. This study aimed to determine the association between indoor air quality and the workers’ health performance in XYZ Company. A cross-sectional comparative study was conducted among 117 respondents. Assessments on IAQ perception level from staff were conducted through questionnaires, which consist of Indoor Air Quality and Health Performance Survey. The three IAQ variables tested in this study are ventilation, particles contaminant and thermal comfort. DOSH and STRIDE has also measured the IAQ level, which are the concentration of Carbon Dioxide (CO2), Carbon Monoxide (CO), temperature as well as humidity. All data collected were analyzed using descriptive and inferential statistics through SPSS Software. Based on the data analyzed, building occupants’ satisfaction level is identified. Findings show that level of IAQ inside the XYZ Company building is medium level as well as level of workers’ health performance. Results from Pearson Correlation analysis reveal that there is a negative and significant correlation between all three IAQ variables with workers health performance. The impact of IAQ towards workers’ health performance is R2 = 18%. Nevertheless, this research managed to provide better understanding and valuable information on how indoor air quality affects psychological performance and health condition of the occupants in office buildings. Recommendations are made to improve the indoor air quality performance in order to provide a comfortable working environment to the workers.

1. INTRODUCTION
Issues of occupational and health in the office have received tremendous attention from the management since the SARS and H1N1 outbreak in Malaysia. A lot of unidentified complain from tenant and the health and safety group recorded staff in the commercial building. These especially in terms of thermal comfort and humidifier fever have affected the absenteeism and productivity indirectly. Issue of energy efficient led to decreased ventilation rates for most interiors, with increased potential for build-up pollutant. Also, lower levels of potentially harmful pollutants might be expected to have greater effect indoor because of longer exposure times (Spengler & Sexton 2003).
Previous study by other researcher shown Americans, especially in urban environments, spends nearly 90% of their time indoors (EPA and the US Consumer Product Safety Commission, 2005). Contributing to the increase in Indoor Air Quality (IAQ) complaints, office workers today expect a clean, comfortable working environment. This is compounded by the public health concerns about the chemical and biological contaminants in air, water and food (Almond D. 2006). There are many sources of indoor air pollutants and among the common ones are Environmental Tobacco Smoke (ETS) emitted due to burning of tobacco products; various chemical substances such as formaldehyde emitted from furnishings; volatile organic compounds emitted from the use and application of solvents; and ozone emitted from photocopiers and laser printers (DOSH 2005). It should be noted here that ETS has been recognized as a human carcinogen by the International Agency for Research on cancer and exposure to it will increase the risk of coronary heart disease (IARC, 2002).
In the current situation where people concern about sustainability environment, building occupants seek to obtain comfort and efficiency in their office. Occupants demand to have priority in terms of comfortability to use and utilize the facilities and services as it must be fit for purpose of the user as this really need to take into consideration because they are going to spend almost 8 hours every day inside the building. Work productivity of workers may be demotivated and interrupted due to poor indoor air quality conditions. Poor indoor air quality and polluted environmental condition can give impact to workers health and also their works performance (Kamaruzzaman & Sabrani, 2011).
According to Kamaruzzaman and Sabrani (2011) many factors can effect air quality, such as poor and inappropriate ventilation system, terrible workers activities such as smoking inside the building, bad personal habits like unorganized clothes, hair and shoes, any product being used in the building such as powder and fiber, and lastly any processing method done such as heating, sawing, grinding or crushing. Therefore, by providing good air quality and comfortability in building can help to achieve better level of IAQ (Cheong and Choong 2001).
Sekhar, Tham & Cheong (2002) pointed that surveys and interviews with the building manager would provide additional information, which represent the evaluation of the users of the building. This paper is therefore purposely to determine the impact of IAQ towards workers health performance and the parameter that will be taken to analyze the condition in the buildings are namely i),Ventilation ii) Thermal Comfort, and iii) Particles Contaminant
According to Mahdi C. I and Zalini Yunus(2010), IAQ in Malaysia has become a critical issue and this has been approved by Department of Safety and Health (DOSH) 2005. In a review of literature conducted by Seppanen and Fisk (2002), they found that there was an increase in SBS symptoms associated with mechanically ventilated buildings, though they could not conclude the reasons for such an increase. More than eleven studies from six countries in Northern Europe and one from the United States of America (U.S.) were included in the review. Multiple deficiencies in Heating, Ventilation, and Air-Conditioning (HVAC) system design, construction, operation, or maintenance may contribute to the increases in symptom occurrence, including deficiencies that lead to pollutant emissions from HVAC systems. It is a known fact that the worker’s well-being and performance are affected by various aspects of the building, included but not limited to, exposure to daylight and access to views, air quality, temperature, odors, VOC, humidity, the design of the built environment, and opportunities for social gatherings and relaxation (Kolleeny, 2003; Madhavi and Unzeitig, 2005;Smith and Pitt, 2009). In addition, since people spend most of their time indoors and the IAQ has an impact on the workers (EPA and the U. S. Consumer Product Safety Commission, 1995), it is beneficial to get feedback from the workers themselves (Zagreus et al., 2004).
A lot of complaints from the occupants inside the building regarding the health problems heard. Based on the sick leave records 65% of the sick leave is because of the SBS Symptoms which are headache, fatigue, throat, and asthma. The frequency of staffs having sick leave has been increase from 11% to 53% since 1 year ago. Thus, this study was conducted to determine the impact and association of IAQ towards workers health performance in terms of safety engineering.

2. METHODOLOGY
A survey has been conducted at XYZ Company through questionnaires. The purpose is to investigate the level of staffs’ satisfaction on ventilation system, particles contaminant, thermal comfort and health performance. The place was chosen because this building used centralized air conditioning system and completely relies on ventilation system in providing air for the staffs in the building since this building is a confine space. There were 117 respondents who worked extensively 8 hours in the office daily involved in this survey. XYZ Company is comprised of six divisions which are Sel Pengawasan, Sel P4 Tumpangan RPS,Sel Bantuan, Sel PUSKOM, Sel Senggaraan and Sel Risik dan Selamat. All of these divisions were involved in these questionnaires.
A Data Analysis
Data was analyzed using the SPSS version 20. Both descriptive and inferential statistics were used for data analysis. The descriptive statistics that been used were percentage, frequency and mean score. All the data been tabulated in table and graph form. It simplified the calculation of percentage and easy to generate chart and graph. Inferential statistics been used were Pearson Correlation and Multiple Regression to test the research hypotheses. All hypotheses were being tested at 0.05 significant levels.

3. RESULT
As refer to the data collected, analysis has been made in getting the results of the evaluation made by the staffs. All the data tabulated basically based on the three objectives in this study which are first to investigate the level of IAQ and workers’ health performance, second to determine the relationship between IAQ and workers’ health performance and lastly to examine the impact of IAQ towards workers health performance.
A Demographic
All respondents involved were male which is 100%. Most of them 57.2% were age 41 years old and above. 75.2 % from them have been working in XYZ Company Building for more than 6 years.
B Mean Score
The overall mean score for IAQ is 2.37, which is medium. Table 1 shows the four variables and mean score tested in this study.
Table 1: Variable and Mean Score

Variable | Mean Score | Level | Ventilation | 2.08 | Low | Particles Contaminant | 2.57 | Medium | Thermal Comfort | 2.47 | Medium | Workers Health Performance | 2.78 | Medium |

C Relationship between IAQ variable and Workers’ Health Performance

Figure 1: Correlation of three independent variables of IAQ and Dependent variable health performance

Fig 1 shows that all three independent variables (ventilation, particles contaminant, thermal comfort) have relationship with the dependent health performance variable. Study results reveal an observed significant negative relationship between particles contaminant and health performance (n (117) r= - 0.372, p<0.01). The coefficient of linear association supports the degree to which particles contaminant relates with health performance. Thermal comfort and ventilation also shows significant negative relationship with health performance (n (117) r= - 0.252, -0.276, p<0.01) accordingly. Negative significant means that as the level of IAQ increase the number of workers sickness problems decrease. Therefore it can be concluded that all three independent variables (ventilation, particles contaminant, thermal comfort) have significant correlation with the dependent variable (health performance) with particles contaminant shows the strongest relationship followed by ventilation and thermal comfort.
D Impact of IAQ towards Workers Health Performance
In order to determine the impact and contribution of the IAQ parameters towards the workers’ health performance as the dependent variable a regression test has been conducted. As analyzed using SPSS Software, R2 is 0.184 which means the IAQ variants explain 18.4% of impact towards the health performance.
Then, the Anova F = 8.478 is significant. This means that all three parameters of IAQ have significant relationship with health performance. Meanwhile, Beta (β) Coefficients value shows that only two IAQ parameters give contribution towards health performance. The most strong contribution or highest β coefficient significant is particle contaminants with -0.549 followed by ventilation with -0.18. Thermal Comfort does not give contribution towards workers health performance. With significant >0.05 and negative β value, it reveals that if one unit of particles contaminant increase the sickness will reduce 54%.Similarly for ventilation , when one unit of ventilation being increase the sickness will reduce 18%.
As in conclusion, among the three independent parameters only two parameters play crucial role in contributing toward the workers’ health performance which are particles contaminant and ventilation.
To complement this study, discussion of findings is focusing to all the three objectives of the study. This is to determine the extent to which these three objectives were achieved overall.

4. DISCUSSION
A Level of IAQ in Their Office Buildings; in Terms of i) Ventilation, ii) Thermal Comfort and iii) Particles Contaminant and Level of Workers’ Health Performance.
The first objective was to determine the level of IAQ in their office buildings; in terms of ventilation, thermal comfort and particles contaminant. It is important to be seen as a measured level of satisfaction is the essence of the study and also serves as a measure to see the validity of the data available to assess further these objectives.
Elements of workers satisfaction on indoor air quality are ventilation, thermal comfort, and particles contaminant. Once the data is analyzed, the overall findings showed that majority of the respondents are in medium level (mean=2.37) in terms of ventilation (mean=2.08; low), particles contaminant (mean=2.57; medium) and thermal comfort (mean=2.47; medium).
IAQ level is one of the indicators to determine the air quality in the office building in term of ventilation efficiency and adequacy. Based on the results obtained, the ventilation system in this building is not efficient. The respondent’s majority does not satisfied with the air circulation in the building. In fact measurement data gained from DOSH and STRIDE also proven that the ventilation system in this building has worn out. As supported by a study conducted by Bohanon et al. (2005) saying that smooth and good air circulation inside a building is very important to be maintained to all the staffs to ensure that all the staffs can breathe well as its indicates that the ventilation system is working effectively.
Respondents mostly dissatisfied with the amount of clean air available inside the office which is caused by poor air filter and ventilation fan maintenance and service. Similarly, a previous case study conducted by Ooi et al. (1998) mentioned that good combination of natural ventilation by adequate opening window and door as well as effective mechanical ventilation fan and air filters provided in the building can help to provide fresh and clean air consistently. He reveals that 69% of IAQ level depends on ventilation efficiency which consistence with this study. Many studies also showed a high incidence of symptoms and complaints in mechanically ventilated buildings (Mendell & Smith 1990).
In this survey, some of the respondents also stated that the thermal comfort environment is acceptable to them, but preferred to be cooler/warmer in the thermal preference scale. These findings reflect the research done by Feriadi and Wong (2004), where people in the hot and humid climate generally prefer cooler environmental condition.
The issues that need to be highlighted the most under particles contaminant parameters are about obedience of staffs towards non-smoking area signage, and office cleanliness on dust and spider web at ceiling and furniture. These issues have decreased the satisfaction of IAQ level inside the building. According to Yang et al. (2008) uncontrollable smoking habits can give bad impact to the IAQ level inside the building, which it can give significant potential to the concentration of particles contaminant in the air. Furthermore this issue is also in line with a study done by Martin et al. (2007).He stated that smoking habits inside building can increase the particles contaminant level which reduce the IAQ level.
Level of workers’ health performance has been identified through surveys conducted stated that it is in medium level. Most of the respondents experienced the difficulty in breathing, having nasal symptoms, throat symptoms, aches and pain as well as feeling sleepy and exhausted. All these symptoms are most likely SBS symptoms which occur because of poor IAQ level. Symptoms have been correlated with larger open plan offices with occupants being more likely to perceive thermal discomfort, poor air quality and noise while also demonstrating more complaints of illness than occupants in cellular offices (Pejtersen et al 2006).
Thus, the findings can be seen that the level of satisfaction on indoor air is medium. The respondents were shown their satisfaction in some IAQ elements but otherwise shown their dissatisfaction on the other elements. Overall IAQ and health performance level is medium
B Relationship between indoor air qualities with the workers’ health of performance
In the third objective, the researcher attempted to see whether indoor air qualities have relationship with the workers’ health of performances or not. The analysis showed that all indoor air qualities variables have relationship with workers’ health performance. Particles contaminant has the strongest relationship followed by ventilation and thermal comfort.
In the current situation where people concern about sustainability environment, building occupants seek to obtain comfort and efficiency in their office. Workers demand to have priority in terms of comfortability to use and utilize the facilities and services, as it must be fit for purpose of the user. Work productivity of workers may be demotivated and interrupted due to poor environmental conditions.
Several studies on the strong association between particles contaminant and health performance which been identified in this study has also been supported this possibility. As for example, Zapulla(2008) revealed that high concentration of airborne, particles dust, and aerosol have high relationship towards health performance of the workers.
This finding is line with Wargocki et al. (2002) which published a report related with some quantitative relation between indoor air quality to workers’ health performance and productivity. He proved that the sick leave rate increase as the ventilation system rate reduces. In the report its stated that doubling the average ventilation rate to 24 L/s–1 per person would decrease the sick leave prevalence in an office from 2% (5 days per year) to 1.5% (3.8 days per year).
Similarly goes to a study conducted by Grimsurd et al. (2007) which done a research on investigating the relationship between ventilation system, level of CO2 and health performance. The findings proved that as the ventilation system runs effectively, level of CO2 decrease gradually(1500ppm) which still more than desired and the rates of students absent due to sickness reduce as well(20%).
Meanwhile, a recent study by Bjarne Olsen, chairperson for the International Center for Indoor Environment and Energy (ICIEE) in Denmark, indicated that improved thermal comfort, reduction in indoor pollutants of particles contaminant, and enhanced ventilation rates and effectiveness can increase workers health performance by 5 to 10 percent. Conversely, the research also indicates that a 10 percent decrease in tenant satisfaction with IAQ results in a 1 percent drop in health performance and productivity indirectly.
In addition, this study is also consistent with research done by Leyten et al. (2012) which reveals that the health performance of the workers is higher when in an air-conditioned environment with the matching comfort temperature approximately 22 degrees Celsius. In air-conditioned environments the prevalence of building-related symptoms including headache, fatigue and difficulty in concentrating is higher compared to free open air environment. This situation in parallel for dissatisfaction with the thermal environment and the indoor air quality which poor thermal comfort condition will bring difficulty in breathing, headache, and fatigue (Tanabe and Nishihara, 2004).
Hence, the analysis carried out clearly showed that majority of the respondents indicated that their health performance is decreased due to poor indoor air quality. Thus the XYZ Company management must be planning a variety of programs to improve IAQ level in their office building therefore the workers’ health performance as a whole can be further improved.
C Impact of Indoor Air Quality in the XYZ Company towards workers’ health performance
The fourth objective of this studies which to determine the impact of indoor air quality variants towards workers’ health performance has successfully achieved.
Many studies have found that occupants of office buildings with above-average ventilation rates (up to 40 cfm per person) have 10% to 80% fewer sick building syndrome (SBS) symptoms at work. A statistical analysis of existing data has provided a central estimate of the average relationship between SBS symptom prevalence in office workers and building ventilation rate. This analysis indicates a 15% increase in symptom prevalence as the ventilation rate drops from 17 to 10 cfm per person and a 33% decrease in symptom prevalence rates as ventilation rate increases from 17 to 50 cfm per person (Gibson, 2010).
There are also several studies that also supported this result which stated that ventilation and particles contaminant will give big impact towards health performance. Poor level of ventilation system and particles contaminant will have the impact of SBS and BRI symptoms like fatigue, drowsiness, throat irritation and chest tightness. From the result of indoor air pollutants and SBS comparison, the most significant pollutant that influences the SBS was CO2, CO, and TVOC (particles contaminant). Nazihah M Salleh et al (2011) study supports this study that inadequate of ventilation system lead to poor air circulation in the building which SBS Symptoms will occur among workers.
Indoor air pollutant result from this study showed that, the indoor air pollutant CO2 mean was lower compared to previous study conducted by Ooi et al. (2008). Increasing the level of CO2 in each building showed positive association to the occurrences of sick building syndrome thus increases in certain lower respiratory syndrome (Michael et al. 2000).
In addition, there are three critical reviews of this literature have been performed which in line with results gained. In the review by Seppänen et al. (2009), 20 out of 27 studies found a statistically significant increase in reporting of at least one SBS symptom among occupants of the study buildings with lower ventilation rates. In nine of these studies, there was at least an 80% increase in the fraction of occupants reporting at least one of the types of SBS symptoms in the buildings with lower ventilation rates. The second critical review was performed by an interdisciplinary group from Europe and concluded that by increasing the ventilation rate decreases the prevalence rates of SBS symptoms. This interdisciplinary group also concluded that ventilation rates below 25 liters per second per person [53 cfm per person] in offices can increase the risk of health and comfort problems (Michelle, 2011). The third critical review by another interdisciplinary group concluded that higher ventilation rates in offices, up to about 25 L/s [53 cfm] per person are associated with reduced prevalence of sick building syndrome symptoms (Ooi et al., 2008).

5 CONCLUSION Overall, this study shows that the level of workers satisfaction on indoor air quality at XYZ Company office building is medium. Its reveals that good level of IAQ will give better workers health performance. The results obtained from this study can be used as the control measure of IAP source in the future XYZ Company buildings by comparing the levels of air pollutants and air quality levels to the standard of Indoor Air Quality (DOSH, 2010). The findings may help the XYZ Company’s management to ensure that the health of all their workers are not affected by the indoor air problems or experienced any sick building syndrome (SBS) repeatedly in the future through the improvement of air quality levels. To maintain a good indoor air quality inside the buildings, occupants should practice good housekeeping; isolate fax-machines and printers have as well as conduct and manage periodical ventilation system maintenance. The most practicable control measures for indoor air problems are by controlling them at point of source. This is essential because the good indoor air quality can ensure that the health status of the office workers and the healthier the workers, the better their performance at work.

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