Indoor air quality research within a furniture factory

Abstract

Improving conditions and quality of life depends, among others, on the environment. People spend most of their time in a day inside buildings to work, sleep, eat, rest, and do sports and other activities. The article refers to a case study based on research on indoor environment within a furniture factory; the research is achieved via instruments for collecting diverse indoor parameters, such as temperature, CO 2 , PM (particulate matter) concentrations, noise, and humidity levels. All data recorded are needed to evaluate the conditions of the indoor climate in which the workers are activating. The measuring methods are shortly introduced and the IAQ (indoor air quality) index is expressed. The personnel activating in this factory is working intensely, standing up, and having to wear a mask considering the Covid-19 context. Thus, it is important to depict each aspect that might trigger a concern if IAQ limits are over passed, not mentioning the synergetic context of the diverse effects. Through revealing the IAQ, and the comfort/discomfort level PMV/PPD (predicted mean vote and predicted percentage dissatisfied) employees and company management can benefit from this awareness and enhance the behaviour in such a way that one might improve the indoor condition. The rapid and irreversible climate changes, mostly due to increasing pollution level and exhaust of greenhouse gases should push humanity to make more studies of this kind and, accordingly, realize the need of improvement and development of new solutions whereby one can sustain the indoor environment as proper as possible, in addition to the outdoor climate.

Full text

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Indoor air quality research within a furniture factory
R V Corlan1, I Ionel1*, M E Boatca2, A Draghici2, R M Balogh1 and D Bisorca1
1Politehnica University of Timisoara, Faculty of Mechanical Engineering, Bv. M
Viteazu 1, 300222, Timisoara, Romania
2Politehnica University of Timisoara, Faculty of Management in Production and
Transportation, 14 Remus Street, Timisoara, 300191, Romania
E-mail: ioana.ionel@upt.ro
Abstract. Improving conditions and quality of life depends, among others, on the environment.
People spend most of their time in a day inside buildings to work, sleep, eat, rest, and do sports
and other activities. The article refers to a case study based on research on indoor environment
within a furniture factory; the research is achieved via instruments for collecting diverse indoor
parameters, such as temperature, CO2, PM (particulate matter) concentrations, noise, and
humidity levels. All data recorded are needed to evaluate the conditions of the indoor climate
in which the workers are activating. The measuring methods are shortly introduced and the
IAQ (indoor air quality) index is expressed. The personnel activating in this factory is working
intensely, standing up, and having to wear a mask considering the Covid-19 context. Thus, it is
important to depict each aspect that might trigger a concern if IAQ limits are over passed, not
mentioning the synergetic context of the diverse effects. Through revealing the IAQ, and the
comfort/discomfort level PMV/PPD (predicted mean vote and predicted percentage
dissatisfied) employees and company management can benefit from this awareness and
enhance the behaviour in such a way that one might improve the indoor condition. The rapid
and irreversible climate changes, mostly due to increasing pollution level and exhaust of
greenhouse gases should push humanity to make more studies of this kind and, accordingly,
realize the need of improvement and development of new solutions whereby one can sustain
the indoor environment as proper as possible, in addition to the outdoor climate.
1. Introduction
The increasing interest in indoor air quality (IAQ) generated a rising number of research papers
published on this theme, with the aim of qualitative and quantitative assessments and development of
policies, standards, and regulations worldwide [1].
Due to the global warming and the pollution increasing in the city, IAQ has become an important
subject of debates when analysing and assessing workplace wellbeing [2]. Measuring and analysing
the related parameters of the IAQ has been improved, but dust spectrography and dust control remain
a field of continuous debates and interpretations; different context of measurements has provided
general framework of the investigations and have created new opportunities for other indoor
investigations, too [3, 4, 5].
The problem has arisen in the case of furniture manufacturing plants, where indoor air pollution in
the form of dust has a negative impact on the health of workers [4, 5]. Standards, norms and the legal
framework have tried to include dust control elements as parameters required to assure operational
licenses. Literature review led to the conclusion that numerous studies aim to research one or another

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parameter of IAQ, but no paper provided a comprehensive overview of indoor physical environment
in a furniture factory by studying dust, microclimate, and noise altogether. From this perspective, the
current study aims to be original research on indoor work environment in a Romanian furniture
manufacturing company.
2. Research methodology
2.1. The research scenario
Dust, microclimate, and noise (regarded as parameters of indoor environment) were measured in a
furniture manufacturing company operating in Timisoara, Romania. Research methodology is
presented in the form of a process flow chart in Figure 1.
Figure 1. Process flow chart of research
methodology
Research was initiated with a thorough research of applicable national legislation and relevant
standards for measurement and interpretation of results. The synthesis of this step is reflected in Table
1, which contains a series of legislative acts and relevant standards regarding occupational exposure to
noise, dust, and microclimate-related factors.
The standards and applicable legislation presented in Table 1 were used for interpretation of
measured values and determination of measurement approach. For example, ISO 9612:2006 standard
presents a detailed framework for measurement of noise in various scenarios, while Government
Decision 1/2012 provides maximum acceptable levels of dust for various types of wood (inhalable
fraction).

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Table
1
.
Determination
of noise, microclimate
,
and dust at
the workplace: a
ppl
icable
laws and standards in Romania for furniture manufacturing industry
Parameter
Name Type
Noise Government decision 493/2006 regarding minimal
health and safety requirements referring to workers’
exposure to risks generated by noise Legislative act
Noise STAS 7150-77 Industrial acoustics. Methods for
measuring noise level in industry
Standard
(applicable
only at
national level)
Noise ISO 9612:2009 Acoustics - Determination of
occupational noise exposure – Engineering method Standard
IAQ
Government Decision 53/2021 to modify Government
Decision 1218/2006 establishing minimum
requirements for health and safety at work to ensure
workers’ protection against risks related to chemical
agents, as well as Government Decision 1093/2006
regarding minimum health and safety requirements
for workers’ protection against risks related to
exposure to carcinogens and mutagens at work
Legislative act
Dust,
IAQ Government Decision 1/2012 to update Government
Decisions 1218/2006, 1093/2006 and 355/2007 Legislative act
Dust Government Decision 355/2007 regarding supervision
of workers’ health Legislative act
IAQ Government Decision 1091/2006 regarding minimum
health and safety requirements at work Legislative act
All Law 319/2006 of Health and Safety at Work Legislative act
The second step of the research consisted in a site visit to understand particularities of the physical
environment, to observe work organization and discuss with production and health and safety
managers to achieve a comprehensive overview of the workplaces planned for analysis.
The third step consisted in preparation and calibration of apparatus and performing the
measurements as per standards and legislation already presented in Table 1. Further, data was
transferred to computer devices and analysed with dedicated software. Based on observations in
second stage and conclusions derived from data analysis, the authors proposed a series of
improvements that would minimize risks involved by exposure to analysed parameters.
It is necessary to mention that the furniture company manufactures both standard and customized
products. Therefore, operations are split between completely automatized manufacturing of wood
parts (processing cells), semi-automated operations (such as edge application, milling and drilling) and
manual operations prominent especially in the case of customization of wood parts (special works). To
obtain a complete overview on the indoor environment in the factory, measurements were performed
at multiple workplaces relevant for each category of operations.
2.2. Microclimate conditions and noise - measurement with Testo 816-1 and Testo 480 apparatus
Noise measurements were performed with testo 816-1 sound level meter, which allows measurement
of noise in workplaces, industrial and production environments, and public places [6]. With a
measuring range of 30 … 130 dB(A) and a frequency range of 20 –8,000 Hz, the Testo sound level

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meter has a memory of 31,000 data sets. Another valuable feature of this sound level meter is the
associated software that enables data transfer to computer devices and analysis of each dataset
(including charts). As per ISO 9612:2009 methodology, the measurements were taken at a height of
170 cm (the level of workers’ ear) considering that the workers perform tasks only in standing
position. In addition, position of workers during tasks was considered when positioning the apparatus
for measurements.
Microclimate parameters were measured using Testo 480 apparatus, a climate measuring
instrument. The apparatus measures temperature, humidity, air velocity, pressure, CO2 and lighting
[7]. The main advantages of the Testo 480 apparatus are: portable device (weights ~435 g), internal
memory capacity for 60,000,000 values, high measurement accuracy, digital sensors, facile
calibration, user-friendly interface and dedicated software for data transfer and analysis [8]. The
apparatus is positioned at workers’ height, in a place reflecting the most frequented areas of each hall.
2.3. Dust particles measurement with Grimm 1.108 optical particle counter
Measurement of airborne dust particles was performed using a GRIMM 1.108 portable laser aerosol
spectrometer and dust monitor. The apparatus uses laser and particle beam to identify particle size and
corresponding concentration; the particle size range is 0.3…20 µm (with 15 channels) and allows a
maximum particle concentration of 0.1 mg/cm3 [9]. Like Testo apparatuses, the particle counter has
dedicated software for data transfer and analysis. To obtain information on workers’ exposure to dust,
during measurements the apparatus was placed at workers’ height (to reflect dust concentration at the
level of workers’ nose and mouth region).
3. Research results and discussions
The chapter presents research results for microclimate, dust and noise, followed by discussion on
findings.
3.1. Microclimate conditions within the furniture factory
Company operations take place in two halls. Consequently, microclimate conditions were measured
for each hall, as the indoor environment for workplaces inside the hall is the same. Majority of
manufacturing operations take place in the first hall, while in the second one only assembly and
packaging for delivery are taking place.
Table 2. Average value of microclimate parameters
Hall Temperature
(˚C) Humidity
(%) Air velocity
(m/s) CO2
(ppm) PMV PPD
(%)
1 23.1 44.9 0.003 618.0 1.53 52.7
2 20.9 47.5 0.000 699.2 1.29 39.9
3.2. Analysis of the dusting level within the furniture factory
The airborne dust level inside the two halls was measured for five workplaces: assembly, special
works, drilling and milling machine, edge application machine and processing cell. Table 3 presents
the average values obtained after measurement of dust by fraction (alveolic, inhalable and thoracic).

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Table 3. Average levels of dusting by fraction for analysed workplaces
Fraction
(mg/m3) Workplace
Assembly Special
works Drilling and
milling
machine
Edge
application
machine
Processing
cell
Inhalable Average 0.57 2.12 0.23 0.13 0.28
Minimum 0.21 0.49 0.05 0.02 0.01
Maximum 2.47 11.36 0.86 1.06 1.34
Thoracic Average 0.36 1.17 0.13 0.08 0.13
Minimum 0.19 0.39 0.05 0.02 0.01
Maximum 1.17 4.67 0.38 0.22 0.41
Alveolic Average 0.11 0.33 0.05 0.03 0.03
Minimum 0.08 0.14 0.02 0.01 0.01
Maximum 0.33 1.27 0.10 0.05 0.07
Table 3 shows that in the analysed factory the average values of wood dust are considerably below
the 3 mg/m3 exposure limit. Figure 2 presents indoor air quality expressed in µg/m3 by type of
particles (alveolic, thoracic and inhalable fractions) for the five workplaces analysed in the study. The
charts highlight that special works involve considerably higher risk of exposure to dust, with the peak
dust level being ~8,000 µg/m3 for the inhalable fraction.
Figure
2
.
I
AQ
–
values
measure
d at 1 minute
-
intervals: a. assembl
y, b.
special w
orks, c. drillin
g an
d
milling machine, d. edge application machine, e. processing cell
b.
d.

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3.3. Analysis of the noise level within the furniture factory
Noise level was measured at five workplaces as follows: assembly, special works (for milling,
polishing, and cutting operations), drilling and milling machine (at the command panel and start/stop
area), edge application machine (command panel area) and a processing cell (command panel area).
Measured average noise levels for each workplace are presented in Table 4. For all the workplaces,
average noise level did not overpass the superior exposure value of 85 dB (A) recommended in
Government Decision 493/2006, meaning that overall workers are not exposed to high risk from this
point of view. However, for milling and polishing tasks, noise recorded significant variations, with
peak levels overpassing the superior exposure value recommended by law (101.4 dB for milling and
90.9 dB for polishing).
Table 4. Average noise level measured for selected workplaces
S. no. Workplace Average measured value (dB)
1 Assembly 66.01
2 Special works - milling 81.80
3 Special works - polishing 81.53
4 Special works -cutting 75.51
5 Drilling and milling machine – command panel 79.93
6 Drilling and milling machine – start/stop area 77.77
7 Edge application machine 83.37
8 Processing cell 79.00
Figures 3 and 4 present noise variations for milling and polishing tasks, highlighting peak and
minimum noise levels. A concerning aspect highlighted by the two charts is the significant fluctuation
of noise level, involving exposure to sudden increases in noise level. This involves risk of hearing loss
if workers are exposed for long periods of time.
Figure
3
.
Noise
measurement
in the
case of the
milling operation a
Figure
4
.
Noise
measurem
ent
in the
case of
the
polishing operation a
a Red line highlights peak levels and blue line highlights minimum measured noise level
3.4. Discussion
Level of CO2 is a strong indicator of indoor air quality, values under 1,000 ppm being considered the
safety upper limit for CO2 concentration [1,10]. The US Department of Labour elaborated an
Occupational Health and Safety Administration Technical Manual (OTM); as per section III chapter 2
of the OTM, CO2 concentrations above 600 ppm determine minimal complaints on air quality at the
workplace [10]. Taking into consideration that the furniture factory does not have any ventilation
systems in the two analysed halls, measured concentrations of CO2 reflect the necessity of
implementing a solution to ensure a higher quantity of fresh air. Additionally, all microclimate factors
have a combined effect generating potential discomfort in the workplace: temperature in the first hall

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is higher than recommended for work in standing position and air velocity is very low. This is
confirmed by the PMV/PPD report, where PMV was above 1 for both halls, while PPD was ~53% for
the first and ~40% in the second hall, respectively.
Microclimate parameters are significant not only for assessment of comfort, but also for a
comprehensive overview of risk of exposure to dust: high humidity and low temperatures reduce dust
circulation in air [11]. Therefore, the combination of high temperature and relatively low humidity
recorded in the factory enhance dust circulation, potentially intensifying health risks for exposed
workers.
According to the Romanian Government Decision 53/2021, the dust exposure limit for an eight-
hour shift is 10 mg/m3 (inhalable fraction). In the case of wood dust, limit value for workplace
exposure is 5 mg/m3 for softwood dust and 3 mg/m3 for hardwood dust (inhalable fraction).
Nevertheless, research on 15 Australian furniture factories indicates there is minimal difference
between exposure to various types of wood used [12]. In the analysed factory, average inhalable
fraction of airborne particles was well below the exposure limit, a result consistent with findings of
extensive research on exposure to wood dust in the European Union [13]. This is mainly due to the use
of effective exhaust systems, retaining majority of dust exhausted during operation.
However, analysis of measured values highlights fluctuations and high levels of airborne particles
during manual operations (special works); at this workplace there is no exhaust system, hence the high
levels of dust generated expose workers to considerable risk. A comparative study conducted in two
furniture factories revealed that exhaust systems reduce the risk of exposure to dust but do not ensure
complete protection, as IAQ in a furniture factory is affected by alveolic particles, smoke, and volatile
organic compounds [14]. This confirms the importance of setting an exhaust and ventilation system
for special works in the analysed factory, as fluctuations in quantity of dust propelled during certain
operations expose to sudden changes in IAQ. Lastly, noise levels did not overpass (on average) the
maximum exposure limit. Similar studies on noise evaluation indicate noise exposure levels higher
than 85 dB(A), proving necessity of workers protection against noise [15, 16]. From this point of view,
in the furniture factory analysed in this study, workers are generally exposed to lower hearing loss risk
as compared to the industry average, mainly due to modern machinery used in production. Along with
dust exhaustion systems, the machinery used in the factory generate lower levels of noise than
previous technologies, creating a safer industrial environment. Nevertheless, results should be treated
with caution, considering that in the case of special works the maximum measured noise levels were
significantly higher than the 85 dB(A) exposure limit.
Based on the analysis of indoor environment parameters, the authors proposed solutions to reduce
workers exposure to health and safety risks. Table 5 presents identified problems and proposed
solutions.
Table 5. Proposed measures to reduce negative aspect of IAQ in the furniture factory
Workplace Problem Solution
Special works Sudden generation of high quantity of
airborne dust and high fluctuation of
measured dust quantity
Installation of dust exhaustion
system
All CO2 > 600 ppm Installation of HVAC system
with continuous check of air
velocity (to maintain it in the
recommended limits)
Special works Exposure to sudden increase of noise
level Introduction of personal
protective equipment
(soundproof headphones)

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4. Conclusions
The study was aimed at analysing indoor environment in a Romanian furniture factory based on
measurement of microclimate, dust, and noise. The apparatuses used enabled accurate and thorough
analysis of proposed parameters, ensuring data reliability. There were no significant abatements from
recommendations and requirements imposed by national legislative framework. However, there were
exceptions identified and their root cause was analysed. Additionally, the study contains a few
improvement proposals to reduce the impact of the analysed parameters on workers’ health. In
comparison with previous research on indoor environment in furniture factories, the current study also
reveals the importance and positive outcomes of new generation machinery and equipment in
reduction of occupational hazards generated by noise, dust, and microclimate conditions.
The originality of this study comes from the assessment of multiple parameters in the same
environment, highlighting the added value of multilateral/interdisciplinary approach to research
industrial indoor environment.
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