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CORRELATION BETWEEN OCCUPATIONAL EXPOSURE TO OIL MIST AND SPRAY FROM METALWORKING MACHINERY AND HEALTH SELF-ASSESSEMENT AMONG WORKERS IN METALWORKING INDUSTRY, LATVIA
Zane Garsele
Sixth year student, Riga Stradins University, Latvia
Edgars Girons Sixth year student, Riga Stradins University, Latvia
Edgars Licis Sixth year student, Riga Stradins University, Latvia
Elza Apeinane Sixth year student, Riga Stradins University, Latvia Dr. Iveta Iljenkova Jurmala Hospital Dr. Zanna Martinsone
Riga Stradins University, Latvia, Department of Occupational and environmental medicine, Latvia Institute for Occupational Safety and Environmental Health, Latvia
Introduction. Oil mist and spray exposure as a part of occupational environment in the field of metalworking industry is associated with number of occupational health issues, particularly various allergic and hypersensitivity reactions.
Aim. The aim was to investigate the potential relation between occupational exposure to oil mist and spray and health self-assessment among workers in metalworking industry.
Materials and methods. Oil mist and spray was collected and analyzed using P-Trak Ultrafine Particle Counter Model 8525 (measures spray concentration by particles per cm2 (pt/cm2)) and electrical low pressure impactor ELPI+ (measures spray concentration by mass, number, surface area - pg/m3 and give particle characteristics by size distribution 6 nm -10 pm). Health self-assessment questionnaire (established by ESF project "The development of up-to-date diagnostic and Research Methods for the risk caused by nanoparticles and ergonomic factor at Workplace" Agreement No.2013/0050 /1DP/1.1.1.2.0/13/APIA /SEDA /025) were conducted on workers (n=36) exposed to oil mist and spray. Questionnaire covered four categories of ques-tions: occupational history, lifestyle, subjective symptoms and satisfaction with health in general. Statistical analysis was done by Microsoft Excel and SPSS 20.0.
Results. Employees of the metalworking companies enrolled in this study were exposed to oil sprays and oil mist in different concentrations. In none of the companies enrolled in our study, the occupational exposure limits of oil mist and oil spray didn't exceeded the occupational exposure limit - 5 mg/m3, regulated by Cabinet of Ministers of the Republic of Latvia.
Complaints about the state of health at the moment among employees in metalworking industry more frequently were registered with increasing age of the employees (p = 0.002) and with higher oil mist and oil spray exposure (number of particles / cm2) in measurements done using the P-Trak Ultrafine Particle Counter (p=0.005).
Longer work experience in metalworking industry is associated with lower results in health self assessment questionnaire. Significant correlation with increasing length of work experience in the field of metalworking industry in total (p=0.012) and length of work experience in the field of metalworking industry in groups (p=0.003) and decreased levels of health self-assessment among respondents was obtained.
Conclusion. As anticipated, workers with longer occupational history in the industry and lower occupational air quality showed poorer self-assessment health rates.
Besides the results of measurement obtained also the technical solutions how the manufacturing process is organized as well as work habits of the workers should be taken in consideration when looking for links between the occupational environment and health conditions. Further research should be done exploring the correlation between the exposure to oil mist and spray and anticipated work-related health issues also including a bacterial and fine particulate contamination of oil mist and spray as an important health hazard. It is required to make additional studies with bigger population and number of respondents to gain more statistically significant results and to get better understanding on effect of oil mist and oil spray on health of employees of metalworking industry. It is important to inform the employees of metalworking industry about the harmful effects of oil sprays and oil mist.
Ключевые слова: Metalworking industry, oil mist and oil spray, occupational exposure to oil mist and oil spray, health self-assessment. Metalapstrade, ellas migla un ellas aer-osols, ellas miglas un ellas aerosola arodekspoztcija, veseltbas pasnovertejums.
SAISTlBA STARP METALAPSTRADES PROCESA RADUSOS ELLAS MIGLAS UN
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AEROSOLA ARODA EKSPOZlCIJU UN METALAPSTRADES INDURSTIJA STRADAJOSO
VESELlBAS PASNOVERTEJUMU, LATVIJA
INTRODUCTION
Metalworking belongs to those working industries were the employees are exposed to various occupational risk factors, furthermore in most of the cases employees are exposed to number of risk factors at the same time, thereby increasing each other's harmful influences [1].
According to the study "Work conditions and risks in Latvia, 2012-2013" companies with key performance areas in manufacture of basic metals are listed between does companies were legislation requirements regarding occupational risk assessment more frequently are not followed. Furthermore nor employers nor employees still aren't sufficiently informed or do
not understand importance of the occupational risk assessment in the process of establishment of labor protection system in the company [2].
In order to reduce heat and friction and to remove metal particles in industrial machining and grinding operations various metalworking fluids are used extensively. At the moment, liquids that are used in metalworking industry are made out of complex chemical compounds, which are divided depending on the type and concentration of containing oils [3, 5, 6]. Regardless of the specific process of metalworking, liquids are richly floated or sprayed over the treated surface as well as between the contact surfaces [3, 4, 5,]. During those processes, liquids undergo mechanical and thermal exposition, resulting in production of sprays. In the working environment, production sprays are found as mist, steam, smoke, gas, metal particles and bio-sprays. These by products are outspread by disintegration under influence of and mechanical forces, by evaporation and later condensation under effect of heat, as well as incorrect use of the liquids, whereas liquids are sprayed directly in the air of working space [7].
Aerosols produced in the metalworking industry, such as oil sprays and oil mist, are important and harmful work environment factors affecting health [4, 8, 9]. When evaluating the possible effect of the particles on human health, not only the size of the particles is significant, but also the amount of particles in a set unit of area (concentration), the dimensional size of particles (diameter, surface area and volume) , shape, structure, specific gravity, density and other characteristics [8,10].
The most dangerous and harmful particles are the ones that can be inspired into the lower airways. These are the particles that are smaller than five micrometers, since they have the ability to penetrate lower airways and reach alveoli as well as gastrointestinal tract. Larger particles can cause conjunctivitis and irritation of upper respiratory tract, throat irritation and cause complaints on cumbersome odors [8, 10].
Data of research showed that most of particles produced during the metalworking process are the ones under five micrometers or the inspirable particles [11]. By exploring the apportionment of the inspirable particles even further, fraction of nano-particles exceeds the fraction of torakal fraction. This means that production sprays predominantly consist of smallest of particles with ability to enter the lower airways [12]. Nowadays, the most topical of the small particles are the nano-particles (with size smaller than 0,1 ^m or 100 nm) and the presence of them in air. Pollution of working environment with nano-particles and their potential risks on human health has been recognized as one of the most essential problems and challenges [13].
Employees of the metalworking industry are exposed to oil mist and oil spray inhaling them or in direct contact with the skin. The exposition and contact usually happens at the moment of cleaning or maintaining the machines, when cleaning the produced parts or by the condensation of aerosols on the skin [4, 7, 8, 9].
Production sprays have diverse effects on person's health. Occupational exposure of production sprays is mainly connected with the harmful effects on the airways and skin [2, 9].
Some of the most common symptoms are allergic reaction in airways (allergic rhinitis, hypersensitive pneumonitis, bronchial asthma) as well as in other organs (contact dermatitis, exema, allergic conjunctivitis) [4, 8, 9, 13, 14].
Described lesions of airways varies from upper airway irritation, slightly increased predisposition to upper airway infections and mild, reversible decrease in indicators of
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respiratory functions up to chronic bronchitis, bronchial asthma, hypersensitive pneumonitis and respiratory distress [10, 16, 17, 18].
In contact with the skin production sprays mostly causes allergic contact dermatitis. In case if the production spray is contaminated with biological agents, scene of infectious complications, such as piodermia, may rise [8, 10, 17].
There is a unifying view on positive correlation between long work experience in metalworking industry, appearance of respiratory symptoms and the severity of symptoms [23]. Barring the cumulative occupational exposure to aerosols, there is also significance in ones susceptibility, when looking on varying severity of respiratory diseases [8, 17].
Prolonged exposition to aerosols is connected with development of oncologic processes. Research has described development of skin, urinary bladder, colon, cervical prostate and other oncologic processes [17, 19, 20, 21, 22, 23].
Occupational Exposure Limit (OEL) is a concentration of chemical substances and compounds in the air of working environment, that does not cause decreased health or development of diseases of a person working in the field and that can be discovered using newest investigative techniques, if the chemical exposure is not longer than eight hours per day and not longer than 40 hours per week [24].
Based the regulations Nr.325 of cabinet of ministry of Latvian Republic, OEL of oil spray in the air of workspace is 5mg /m3 [27]. In most of the other countries defined OEL for oil spray matches the OEL in Republic of Latvia - 5mg/m3, as it is in United States of America, United Kingdom and Finland [25, 26]. In other countries OELs for oil spray ranges from 1mg/m3 in Sweden [26] to 3mg/m3 in Japan [25].
MATERIAL AND METHODS
Three metalworking companies in different regions in Latvia were contacted and two of them (further in text - company A and company B) were willing to participate in the study. The study was conducted according to the Helsinki Declaration and the provisions of human rights convention. Approval from RSU Ethics Committee was obtained, that this study fits the ethical requirements.
Oil mist and spray was collected and afterwords analyzed using measuring equipments „P-Trak Ultrafine Particle Counter Model 8525" and electrical low pressure impactor „ELPI+" which enabled to measure spray concentration (by mass, number and surface area) including particles in size distribution from six nanometers up to 10 ^m owned by Riga Stradins university Institute for Occupational Safety and Environmental Health Laboratory of Hygiene and Occupational Diseases (accredited laboratory).
Health self-assessment questionnaire (established by ESF project "The development of up-to-date diagnostic and Research Methods for the risk caused by nanoparticles and ergonomic factor at Workplace" Agreement No.2013/0050 / 1DP/1.1.1.2.0/13/APIA /SEDA /025) were conducted on workers exposed to oil mist and spray. Questionnaire covered four categories of questions: occupational history, lifestyle, subjective symptoms and satisfaction with health in general. In total 36 valid questionnaires were included in this study.
Data obtained from measurements carried out at the metalworking companies and surveys handed out to workers were cross-checked using statistical data analysis. Following statistical methods were used for data processing: Microsoft Excel and IBM SPSS 20.0. Considering the small sample size, Fisher's
exact tests was used to examine the significance of the association (contingency) between the two kinds of classifications. Statistical significance was attained when a p-value was less than the significance level (p < 0,05).
RESULTS OF THE STUDY
Population of research were 36 people from two different metalworking companies - A and B. Age ranged from 18 to 66 years, with median age of 38,4 years (SD=16,9) (Fig.1.). 34 of the subjects were male and two were women. Such gender
distribution can be explained with the specific work conditions and job responsibilities for employees working in metalworking industry. Taking into consideration the wide range of age, in the further study two proportionally equivalent groups were established (Fig.2.). First age group - aged 18 to 30 year olds corresponded with 19 individuals (52,8%), whereas median age was 25,6 years (SD=2,9). Second age group - aged 31 to 66 year olds corresponded with 17 individuals (47,2%), whereas median age was 49,8 years (SD=9,8) (Fig.2.).
Fig.1. Age distribution
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20
15
16 14 12 10
5
6 4 2 0
19
17
IS -30 years old
Age groups
31 - 66 years old
Fig.2. Age groups
Work experience of the respondents was recorded in two ways - experience in the current specific company (A or B) as
well as total work experience in the metalworking industry. Work experience in the mentioned companies varies from six months
to 10 years. Combined work experience in the metalworking industry varied from six months to 39 years. Based on the received data on work experience in the metalworking industry, three groups- separated by work experience in the specific company (A or B) and total work experience in the mentioned
field. First group included all individuals with work experience five years and less, second group included individuals with work experience from six to 10 years, and the third group included individuals with work experience from 11 and more years in the field (Fig.3.).
Fig.3. Work experience in groups
With the help of P-Trak Ultrafine Particle Counter Model 8525, ultra small particle (range of device - from 20 to 1000 nm) concentration was determined, which was expressed as particle count on square centimeter (pt/ cm2). In both involved companies, measurements were done in the breathing area of the employees. Measurements were carried out during the active work process, determining the oil mist and oil spray particle count on square centimeter (pt/cm2).
In the company A, the minimal detected amount of oil mist and oil spray particles were 11900 pt/cm2, the maximal detected particle count was 500000 pt/ cm2. The median value of measurement series was 63825 (SD = 40587 pt/cm2) (Fig.4.). As reference value, the measurements from companies canteen were taken. Canteen had no sources of oil mist or oil spray. The minimal detected particle count in the reference room was 4540 pt/cm2, the maximal detected particle count reached 5760 pt/m2, median particle count in the reference area was 5121pt/cm2 (SD = 610 pt/cm2) (Fig.5.).
The minimal detected particle count in the company B was 10700 pt/cm2, the maximal detected particle count was 48600
pt/cm2, the median value of measurement series was 12630 pt/cm2 (SD = 12226 pt/cm2) (Fig.4.). As reference value, the measurements from companies office premises were taken. Office area had no sources of oil mist or oil spray. The minimal detected particle count in the reference area was 5800 pt/cm2, the maximal detected particle count reached 6590 pt/cm2, median particle count in the reference area was 6232 (SD=323 pt/cm2) (Fig.4.).
In the company A, concentration of particles in industrial premises in all categories (minimal, maximal and median pt/ cm2) were higher, compared to company B (Fig.4.). On the other hand, company B had higher value of particle concentration in the reference rooms, compared to company A (Fig.5.). It can be explained with the fact, that the entrance to the reference area in company B is located right next to manufacturing premises.
The large values and peaks in standard deviation (SD) in both companies can be explained and grounded by the fact, that metalworking is a cyclic process, whereas the highest concentration of particles is observed only at certain moments of work routine.
Company The minimum number of particles (pt/cm2) The maximum number of particles (pt/cm2) Average value (spt/cm2)
A 11900 500000 63825 (SD=140586,64)
B 8650 48600 12630 (SD=12226,42)
Fig.4. Oil spray particles per square centimeter (pt/cm2) in companies industrial premises
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Reference area The minimum number of particles (pt/cm2) The maximum number of particles (pt/cm2) Average value (pt/cm2)
Recreation - canteen area 4540 5760 5121
(company A) (SD=610,23)
Office space (company B) 5800 6590 6232 (SD=322,99)
Fig.5. Oil spray particles per square centimeter (pt/cm2) in reference areas
Oil spray particle number concentration (N) (1/m3), as well as oil aerosol spray particle mass concentration (M) (mg/m3) were measured using electronic low pressure impactor ELPI+ (range of device from six nanometers to 10^m).
In the company A, minimal oil spray N was measured at 47451,98/m3, maximal oil spray N reached 252133,47/m3, the average measurement of N=136905,90 (SD = 85525,20/m3).
In the companies A reference room, oil spray particle count concentration reached 70379,03/m3.
In the company B, minimal oil spray N was measured at 24271,50/m3, maximal N reached 30957,49/ m3, the average measurement of N=26710,22 (SD=2398,23/m3). Oil spray particle count concentration in the reference area of the company B reached 24901, 8/m3 (Fig.6.).
Company N in reference areas (1/m3) N in industrial premises
Minimal N (1/m3) Maximal N (1/m3) Average N (1/m3)
Company A 70379,03 47451,98 252133,47 136905,90 (SD=85525,20)
Company B 24901,8 16818,56 30957,49 17095,39 (SD=2398,23)
Fig.6. Oil spray particle number concentration (N) (1/m3) in the industrial premises and reference areas
In the company A, the minimal oil spray M value was 0,02mg/m3, the maximum M value was 0,06mg/ m3, median M value of the measurements was 0,04 mg/ m3 (SD=0,01mg/m3). Concentration of oil spray in the companies A reference area was 0,3 mg/m3.This result can be explained by the higher amount of larger particles in the air, which results in higher values of M. This means that increased size of particles increases the weight of the measured particles (Fig.7.).
In the company B, the minimal oil spray M value was 0,2 mg/m3, the maxi-mum M value was 0,8mg/m3, median M
value of the measurements was 0,6 mg/m3 (SD=0,24 mg/m3). Concentration of oil spray in the companies B reference area was 0,4mg/m3 (Fig.7.).
When comparing results in the manufacturing rooms of both companies A and B, the company A showed higher values in all of the categories (minimal, maximal and median value of measurements, expressed as particle count in one cubic meter), compared to company B. Whereas, when comparing results from the reference area, company B showed higher values compared to company A.
Company M in reference area (mg/m3) M in industrial premises
Minimal N (1/m3) Maximal N (1/m3) Average N (1/m3)
Company A 0,3 0,02 0,06 0,04 (SD=0,01)
Company B 0,4 0,2 0,8 0,6 (SD=0,24)
Fig.7. Oil spray particle mass concentration (M) (mg/m3) in companies industrial premises and reference area
In the reference area of company A, the nano-particles comprised 97% of all particles in the rooms' air. In the manufacturing premises, nano-particles comprised 96% of all particles in the air. Employees of the company A are exposed to high levels of nanoparticle concentration in both - the reference area and manufacturing premises (Fig.8.).
In the reference room and manufacturing room of company B, the percentage of nano-particles in the air is lower compared to company A. In the reference area - 84%, and in the manufacturing room 71% of all particles in the air (Fig.8.).
In the company B, the employees are exposed to lower levels of nano-particles compared to company A (Fig.8.).
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The average total number of nanoparticles (1/m3) The average total number of particles in total (1/m3) Nano Particle Number (%) of the total number of particles Comment
Company A
Reference area 68111,14 70379,03 97% Employees are exposed to high level of nanoparticle concentration in the air.
Industrial premises 136905,90 (SD=85525,20) 136905,87 (SD=85525,24) 96%
Company B
Reference area 21009,99 24901,80 84% Employees are exposed to slightly lower level of nano-particle concentration in the air.
Industrial premises 17095,39 (SD=2398,23) 24015,81 (SD=5775,03) 71%
Fig.8. Nanoparticle exposure in companies A and B
Fisher's exact test, which is suitable for analysis of small groups, was used to determine the connection between exposition to oil mist and oil spray produced in the metalworking processes and the state of health of the employees of metalworking industry. Results of the measurements gained using P-Trak Ultrafine Particle Counter and ELPI+ were analyzed as well as results from the health self assessment questionnaires filled out by the employees. In all cases, the level of statistical reliability did not exceed p value over 0,05 (p<0,05). Although by using Fisher's exact test statistically significant results were abstained as mentioned above with p value being less than 0,05 (p<0,05) it is more accurate to speak in terms of trends rather than statistical significance.
A correlation has been established between results of data from P-Trak Ul-trafine Particle Counter and data gained from health self assessment questionnaire. There is a trend showing a connection between median air pollution (pt/cm2) and present complaints on health (p = 0,005) - the higher the pollution of air in the workplace, the bigger number of respondents had health complaints at the moment. (Fig. 9.).
By examining the results gained from ELPI+ device, statistically reliable compatibility between obtained N values and health self assessment questionnaire data were not established.
Same goes for data gained from ELPI+ device - M values do not correlate with health self assessment questionnaire answers.
Analyzing the health self assessment questionnaire a trend of a compatibility between age of the employee and health complaints at the moment was obtained (p=0,002), which can be explained with physiological changes of ageing. Employees were divided into two age groups - first one aged 16 to 30 year olds, second one from 31 to 66 year olds. The second age group showed lower health self assessment questionnaire results compared to first age group (p=0,000). This again emphasizes on the decreasing state of health with age (Fig. 9.).
Reliable connection was established between both - work experience in the groups divided by age (p=0,012) and work the numerical value of work experience in the industry (p=0,003) and the data from health self assessment questionnaire.
It means that with increased experience in the metalworking industry, level of self assessed health decreases. Connection between experience in the specific company and level of health self assessment was not established. It can be explained by a fact that several individuals with longer experience in the field had just recently transferred to the particular company.
Due to the small sample of individuals, data from both companies were analyzed together (Fig.9.).
Health self-assessment Heath complaints now Health complaints in previous 6 months
Average concentration level of particles(pt/cm2) 0,336 0,005** 0,528
Age 0,623 0,002** 0,345
Age groups 0,000** 0,146 1,000
Work experience in years (in current workplace) 0,402 0,620 0,136
Work experience in years (in metalworking industry) 0,012* 0,765 0,375
Work experience in met-alworking industry in groups 0,003** 0,214 0,476
*p<0,05 **p<0,01
Fig. 9.Correlation between measurements of oil mist and oil spray and health self-assessment questionnaire
DISCUSSION
Working in metalworking industry is associated with different occupational hazards, one of them includes exposure to oil mist and oil spray. Numerous studies have been conducted disclosing
correlation between exposure to oil mist and spray and their harmful effects on the employees working in the metalworking industry.
Employees are exposed to oil mist and oil spray by inhaling these substances or by direct contact with skin causing various allergic and hypersensitive reactions [4, 7, 8].
Although in none of the companies that participated in our study the occupational exposure limit of oil spray regulated by Cabinet of Ministers of the Republic of Latvia wasn't exceeded, results of our study show a trend in increasing number of complaints registered among those employees that were exposed to higher levels of oil spray concentration in their work spaces. Similar results were achieved in a research carried out in Finland, whereas harmful work related factors proved to affect respiratory tract of employees involved in metalworking. Results claim that respiratory diseases of varying severity developed even to those employees of metalworking industry, which worked under conditions not exceeding the allowed values of OELs. From which it was concluded that in order to lower the incidence of occupational diseases and complications in connection with respiratory tract, the levels of OEL of oil sprays should be lowered. [27].
Discoveries and suggestion done by researchers in Finland can be attributable to situation in the Republic of Latvia indicating that there is a necessity to review and reduce the existing OEL of oil spray.
The fact that not only the structure and concentration of particles in the air has significance on the health of an individual, but also the size of the particles, is becoming more recognized. Oil mist and spray produced during the metalworking processes are mainly composed of small-sized particles less than five micrometers, thus easily entering the lower airways [11, 12].
The presence of nano-particles in the air and their potentially harmfull effect on the airways should be emphasized. The presence of nano-particles in the air of the working environment isn't a completely unexplored area among researchers and labor protection system workers. Potentional risks on human health has been recognized as one of the most essential problems and
challenges. Results of our study also points out the significance of this aspect. Nano-particles were accounted for most of the particles registered in the indoor air of both companies.
Only few countries have worked and enforced legislations regulating OEL for nano-particle in occupational environment [11]. Republic of Latvia isn't one of those countries yet.
As national wide study indicates metalworking industry in Latvia is among those industrial fields that show the most troublesome data concerning occupational health problems and legislations. Lack of understanding among employers and employees regarding occupational hazards is one of the key factors that cause this problem [2].
It is essential to inform and educate both - employers and employees working in metalworking industry about the harmful effects of oil sprays and oil mist and how to protect one's health.
CONCLUSIONS
Employees from both metalworking companies that enrolled in the study are exposed to oil mist and oil spray in different concentrations daily. Nevertheless OELs for oil spray regulated by Cabinet of Ministers of the Republic of Latvia were not infringed in non of the metalworking companies enrolled in the study.
High proportion of nano-particles were detected in measurements made in both industrial and reference premises of both companies enrolled. Conducted measurements shows that oil mist and oil spray produces a high occupational exposure to
nano-particles among employees working in metalworking industry.
Complaints about the state of the health more frequently were registered with increasing age of the employees as well as among those employees being exposed to higher oil mist and oil spray exposure.
Decreasing levels of health self-assessment among employees were abstained with increase of the age of the employees as well as with longer work experience in years in the metalworking industry.
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[24] Legislation of the Republic of Latvia, Cabinet Regulation No. 325 (2007) Ministru kabineta noteikumi Nr.325
"Labour Protection Requirements when Coming in Contact with Chemical Substances at Workplaces"
[25] Hsin-I Hsu, Mei-Ru Chen, Shih-Min Wang, Wong-Yi Chen, Ya-Fen Wang, Li-Hao Young, Yih-Shiaw Huang, Chung Sik Yoon, Perng-Jy Tsai: Assessing Long-Term Oil Mist Exposures for Workers in a Fastener Manufacturing Industry Using the Bayesian Decision Analysis Technique. Aerosol and Air Quality Research, October, 2012, 12 (5); 834-842.
[26] Ministry of social affairs and health (2007) "Legislation on Occupational Safety and Health", Helsinki http://stm.fi/ (Accessed 24.03.2016)
[27] Jaakkola MS, Suuronen K, Luukkonen R, Jarvela M, Tuomi T, Alanko K, Makela EA, Jolanki R: Respiratory symptoms and conditions related to occupational exposures in machine shops. Scandinavian journal of work, environment & health, January 1, 2009; 35 (1); 64-73.
