Assessment of indoor air quality in comparison using air conditioning and fan system in printing premise

Printers contribute to various emissions consist with chemical contaminants. High concentration of the particulate matter can cause serious health problems. This study focuses on the indoor air quality in printing premise unit in Universiti Tun Hussein Onn, Malaysia. Field testing involving air sampling methods were taken from 900 hours to 1600 hours, for every 30 minutes using physical measurement which is Multi-Channel Air Quality Monitor (YESAIR), E-Sampler and Ozone Meter. Air sampling was recorded based on one sampling point and most suitable point for production. A comparison based on different ventilation using fan and air-conditioning were also taken and results is being compared based on OSHA and NIOSH standards. Besides that, the statistical analysis is being conducted in order to predict the effect on number of printers. From the result, the O3 concentrations show, 10% reduced for printing premise using fan ventilation compared to air-conditioning but remain the same value for PM2.5. The concentration of O3 increased when the number of printers decreased, while the concentration of PM2.5 increased the increase of printers number. Overall, the use of fan in printing premise is more suggested since the level is slightly lower than the printing premise using air-conditioning.


Introduction
Air is a precious resource for all humans and living things.Indoor air quality is significant to the human since most of the time spent in the buildings.According to Mohd Dzulkifli S.N. et al. (2014), poor level of indoor air quality since indoor air pollutants is not easy to dilute compared to outdoor pollutants.There are many factors that damage the air quality from rapid development such as increasing number of vehicles, factory's waste, dusts from construction works, industrial sources and materials use for building.Some of the electrical components used in the building are computers, printers, copiers and other electronic equipment [1].The Environmental Protection Agency (EPA) defines Indoor Air Quality (IAQ) as the temperature, humidity, ventilation and chemical or biological contaminants of the air inside a building [2].
Nowadays, printing services are very popular and it has been widely used in Malaysia.It became one of the most important services for people in their daily lives.Printing services have been used by many people include the workers and students from school or university.The services provided by printing premises are photocopy, scanning, binding and lamination, booklet and nametag.It is a well-known the fact that in the printing process hazardous substances occur in the air, threatening human health [3].There are few potential source from indoor pollutants from printers [4,5] whereby the main pollutants identified are from volatile organic compound [6], ozone [7] and fine particles [8].One of important factor in indoor environment is fine particle due to the effect to health and also for how inhabitants perceive the environment [9].
According to Kim et al. (2008), a fuser or also called as a toner fixation unit released a particles and addition to it, different condition of fuser from the operation of printer may contributed to different size of particle distributions.Damanhuri et. al., 2015 report that the emission rates of compound are significantly influence by printer speed and the coverage of printing job that affected the quality of indoor environment.Kiurski, J. S. et al., 2013 added that the printer that were used in printing premises for printing services is one of the items that emit the air pollution and it will lead to poor air quality.Some illnesses such as cough, headaches, eyes irritation or dizziness were caused by poor air quality.In a report by World Resources Institute 1998), indoor air pollution has been recognize as a global environmental problem.These pollutants include airborne particles and particulate matter such as gases, toxic chemicals and volatile organic compounds (VOCs).Based on a studies by U.S. Environmental Protection Agency (EPA), there is a cases where level of pollutants for indoor environment are higher than outdoor environment.EPA is concern about particles that are 10 micrometers in diameter which are "inhalable course particles" and below 2.5 micrometers which are "fine particles".Due to Fisk WJ (1987), 'buildings were assumed to shelter occupants from outdoor pollutants and little thought was given to pollutants generated or trapped indoors'.Table 1 shows the list of indoor air contaminants and acceptable limits based on ASHRAE standard 62-2004 and DOSH.
Therefore, this paper investigates the indoor air quality in printing premises.The investigation is directly to monitor the main potential pollutants with is the VOCs Ozone and fine particle.Besides that the IAQ parameters such as the temperature and relative humidity were also being recorded.

Analysis method 2.1 Mapping
Figure 1 shows the position of the printers inside the premise.The arrangement of furniture is being organized based on one cubicle and u-shape desk.

Sampling
The space for printing premise is about 16ft by 20ft with closed door as to control the contaminants value.The location situated in printing premises unit in University of Tun Hussein Onn Malaysia.The field testing involve are from air sampling methods which were taken from 0900 hours to 1600hours, for every 30 minutes using physical measurement which is Multi-Channel Air Quality Monitor (YESAIR), E-Sampler and Ozone Meter.The room temperature ranging in between 26°C-28°C with relative humidity in the range of 50-60 %.

Descriptive analysis
The descriptive statistics parameters that were used for analyses the data collected are the number of data, mean, mode, median, maximum number and minimum number.
From the descriptive statistics, the simpler interpretation of the data can be obtained and the data was presented in a more meaningful way.In order to determine the outliers of O3 and PM2.5, the box plot was used in the analysis.Outlier is an observation point that is distant from other observation.From the box plot obtained, the skewness of data can be obtained.

Correlation analysis
In order to achieve the objective for this research, the correlation analysis method was used.The correlation analysis was used to describe the linear relationship between two continuous variables which is between the numbers of printers operated with the level of contamination indoor air.The correlation measures the strength and direction of the linear relationship.This method can show whether and how strongly pairs of variables are related.

Descriptive statistics
The collected data were analysed and the values of mean, mode, and median were determined and tabulated in the Table 2.The results show that the mean of ground level ozone and PM2.5 are still comply the standard which is 0.05 and 150 μg/m 3 respectively.For comparison purposes, the mean of O3 for printing premise using air-conditioning is slightly high compared to printing premises using fan and based on the value of mean, mode and median, the distribution of monitoring records are almost symmetry or normally distributed.
Based on the monitoring records, the data of O3 and PM2.5 for air-conditioning and fan have been transfer into boxplot.From the information that was obtained from the boxplot, the skewness of the data can be known.The boxplot of the data can be seen in Figure 2, Figure 3, and Figure 4.Both boxplot for O3 and PM2.5 are negatively skewed and positively skewed respectively.Negatively skewed shows that the most frequent data to occur indicate a larger value and as positively skewed means that the most frequent data that were collected are smaller than median.

Correlation analysis
From the data collected, the relationships between the numbers of printers operated with the level of contamination indoor air PM2.5 and O3 were analysed.The correlation analysis method was used in this study in order to analyse the relationship.Table 3 shows the correlation coefficient for concentration of O3 and PM2.5.Based on the Table 3, the correlation coefficient of O3 in air-conditioning and fan system is -0.41 and -0.18 while correlation coefficient of PM2.5 is 0.07 and -0.09 respectively.The relationship for O3 is known as the negative relationship while the relationship for PM2.5 is known as positive relationship.Otherwise, the relationship of PM2.5 for fan is known as the negative relationship.The strength of the correlation can be analyzed based on the guide that Evans (1996) suggests that were tabulated in the Table 4. From the Table 4, the result of correlation of O3 was in the range of 0.4 < r < 0.59 which means the correlations are moderate.Meanwhile, the correlation coefficient of PM2.5 was in the range of 0.0 < r < 0.19 which means very weak.From the result, the concentration of O3 increased when the number of printers decreased.Meanwhile, the concentration of PM2.5 increased when the number of printers increased.Otherwise, the result of correlation of O3 and PM2.5 are in the range of 0.0 < r < 0.19.This indicates that the relationship in between PM2.5 and O3 is very weak.

Fig. 3. Boxplot of O3 in fan system
Based on the result from Brown et al. (1999), there are different results for contaminated indoor air when the number of printer use is different.From the recent reports, it has been identified and measured that the emissions of ultrafine particle were exist during operation of laser printers [4,15] and copiers [16].Further studies are needed to better understanding on the type of printer used and the types of printing activity such as fax, colour printer, copier, and scanner.

Graphical analysis
Figure 5 shows the graph of O3 against time while Figure 2.5 against time.The figure below shows the graph of O3 and PM2.5 against time for ten (10) days which are from 28 th February 2016 until 13 rd March 2016.The guidelines for both O3 that cannot be exceed which is 0.05 ppm.Meanwhile, the acceptable limit based on Department of Occupational Safety and Health (DOSH) for PM2.5 is 150 μg/m 3 .The critical result that was obtained for O3 is 1 st March 2016 and for PM2.5 is 3 rd March 2016.Based on the graph, the reading of O3 rose from 0.018 to 0.022 ppm starting from 12.15 until 2.30pm because on that time the printers are not working or at rest condition.Meanwhile, when the printers were at rest, both contaminations were volatile in indoor air.Also the surrounding was lack of airflow from an outdoor and the air in surrounding was caught at one place.This is the critical part where both contaminant emission from printers.A by-product from printing processes of laser printers and photocopiers is ozone.The fluctuate values of ozone is depending on airflow around printer, ozone diffusion in air, or the characteristic of ozone monitor used in this study [4].

Conclusion
Based on the discussion and the analysis, IAQ inside printing premise unit was found safe to occupants where the levels of contaminants inside the building are low.The result for air temperature, relative humidity, O3, VOCs and PM2.5 shows a positive sign for good IAQ and below DOSH standard and permissible limit by DOSH.Besides that, the relationships between numbers of printers operated with the level of contamination shows that using air-conditioning system, the relationship between the number of printers with the level of contaminate air for O3 is moderate (negative), indicated when numbers of printers operated increase, the concentration of O3 decrease.Meanwhile, the relationship for PM2.5 is weak (positive) indicated numbers of printer increases will cause increasing in concentration.Unlike O3 and PM2.5 the relationship shows a weak results when fan is applied.

Fig. 1 .
Fig. 1.Position of printer in the premise.

Table 4 .
Correlation guideline: absolute value of pearson's coefficient

Table 1 .
List of indoor air contaminants and the acceptable limits

Table 2 .
Descriptive statistics parameters