cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers

by:Gewinn     2019-08-22
Objective: to investigate the relationship between reduced lung function and accumulated exposure of dust and gas in tunnel construction workers.
Methods: there are 651 male construction workers (
Drilling and blasting workers, tunnel concrete workers, grouting workers, tunnel boring machines)
In 2002-1989, an average of six years of lung activity was measured.
Outdoor concrete workers, Foreman and engineers are the reference population for low exposure.
Results: the variation component between workers in the working group was significantly reduced compared to the whole population, suggesting that the level of contact of workers in the working group was similar.
Annual decline inexposed non-
21 ML and 24 ml of smoking workers
People who smoke.
The decline in v1 for tunnel construction workers is 20-31 ml higher than that of low exposed workers, depending on the non-
Smokers and former smokers.
After adjusting the age and observation time, the cumulative exposure to nitrogen and two non-
Smokers and former smokers
Conclusion: cumulative exposure to nitrogen appears to be a major risk factor for decreased lung function among these tunnel construction workers, although other drugs may contribute to observed effects.
Contact with blasting smoke should be avoided, diesel exhaust emissions should be reduced, and breathing devices should be used to protect workers from dust and carbon dioxide.
Method operation description tunnel engineering follows the sequence of drilling, blasting, transporting broken rock out of the tunnel, spraying wet concrete on the tunnel wall, installing and maintaining ventilation pipes, cables, pipe, iron and carpentry work.
There are four groups of workers working mainly in the tunnel, hereinafter referred to as tunnel workers: drilling and blasting workers, tunnel concrete workers, spraying workers and tunnel boring machines (TBM)workers.
Three low-exposure occupational groups as reference groups: outdoor concrete workers, Foreman (
Check in the tunnel)
Engineer (
White collar workers).
Generally, tunnel construction workers work 1550 hours a year, while outdoor concrete workers, Foreman and engineers work 1650 hours.
Other details of the tunnel construction work are described elsewhere.
The research design and research population consists of male workers employed by a major Norwegian construction company.
All employees participated in the health examination, which was mainly conducted at the construction site.
Lung capacity measurements were included in the examination.
All tunnel construction workers, outdoor concrete workers, Foreman and engineers who conducted more than one lung function measurement between January 1-20, 1989 and June 31 were included in this study;
There were 663 workers.
12 workers were excluded from the queue: 3 were due to the lung capacity measurement error and 9 were due to the inability to determine if they were working in the tunnel.
As a result, the study population consists of 651 workers.
The company records provide the following information about each subject: name, social insurance number, title, total number of sick leave hours, weight, age and smoking status.
Among tunnel construction workers, the main information exposed to nitrogen appears to be a major risk factor for decreased lung function.
Carbon dioxide exposed to blasting and diesel power equipment should be reduced.
Construction companies that conduct routine health checks on workers should use this data to obtain information about the occurrence of respiratory diseases in tunnel construction workers and other workers.
As part of a regular company inspection, each worker received a questionnaire.
Smoking status is determined by the following questions: Do you smoke? (yes/no);
If so, how much? (
0, 20 cig/day).
Company doctors and a former long-term tunnel worker independently verified the title of the research population based on their own knowledge of the worker.
They also estimated the average time of engineers and foreman in the tunnel.
The foreman is assigned to 0%, 10% or 20% of the total working hours, while the engineer is assigned to 0% or 10%.
According to this assessment, the title was changed in 15 subjects.
The study was approved by the National Data Inspectorate and the regional medical ethics committee.
The exposure assessment details of the exposure assessment have been given elsewhere, and only a brief description is given here.
Visited 16 tunnel construction sites;
Individual exposure measurements of dust and gas exposure for at least two days were performed at random sampling of workers in each work group, excluding engineers and Foreman.
The shift time is 10 hours, two breaks at a time, 30 minutes at a time.
However, due to the limited battery capacity of the sampling device in a dusty environment, the sampling time is limited to 5-8 hours.
The sampling time is considered to be the representative of the entire work shift, because the sampling period is randomly selected within the shift, and tasks are often repeated on the same day.
Since 1980, there has been no significant change in the calculation of accumulated exposure technology and outdoor concrete construction technology in Norway.
In addition, until 2001, Norway had no regulations on the discharge of underground construction machinery.
11 due to geological differences at different locations, there may be temporary differences in quartz exposure.
However, due to the location of the tunnel construction in all parts of Norway, it is not expected that there will be a long-term difference in quartz exposure.
Exposure measurements cover 33% of all construction projects that the company carried out during the study.
Therefore, it is assumed that the average exposure level within the working group is for long-term exposure to α-
During the study, quartz, in addition to the jet operator.
In 1998, the Norwegian market introduced a new spray concrete rig with a closed cabin, but the measurement results of these rigs were not included in the calculation of cumulative exposure of spray concrete operators, because the use of these rigs during the study period is limited.
Policy measures must be taken to prevent excessive respiratory incidence among Tunnel construction workers, including reducing exposure to diesel exhaust gas and blasting smoke (
Nitrogen, especially)
And dust.
By exchanging diesel power equipment with electric equipment, improving the ventilation system, and using a closed ventilated cab, exposure can be better controlled.
Cumulative exposure of each agent (table 1)
Calculate each worker in the queue by multiplying the time spent in the workgroup by an arithmetic average (AM)
Exposure of the working group.
These calculations are based on the normal working hours of tunnel workers being 1550 hours/year and the normal working hours of other workers being 1650 hours/year.
A 2 ppm carbon monoxide level was assigned to the boring machine staff, which is equal to the detection limit of the read-through electro-chemical sensor.
Exposure to carbon monoxide may be low as exposure only occurs when a diesel-powered locomotive is used to enter and exit the tunnel.
In addition, the TBM equipment is electric and fresh air is continuously supplied to the Palm surface through the ventilation system.
No formaldehyde measurements were made for either the injection concrete operator or the TBM worker.
These workers are assigned to the AM level of drilling and blasting workers (0. 025 ppm)
Because the formaldehyde exposure sources of these groups are the same (
Diesel exhaust mainly)
The location of the workers is similar (
Mainly in front of the tunnel).
Outdoor ambient air levels are considered as estimates of exposure of outdoor workers to sulfur dioxide (15 ppb)
And carbon monoxide (0. 5 ppm)(
Personal communications from Norwegian Institute of Aviation, Kjeller, Norway).
View this table: view inline View pop-up table 1 Cumulative exposure * and exposure of unmeasured engineers and foreman in the tunnel construction workers operation group by comparing these workers in the tunnels of drilling and blasting workers.
Therefore, the engineer is assigned to 0 or 1/10 of the AM exposure level of the drill bit and blasting worker, while the foreman is assigned to the level of 0, 1/10, or the AM exposure level of 1/5 of drilling and blasting workers.
Cumulative exposure was adjusted to sick leave in addition to the engineer, as this information was only recently recorded.
There is no information about the use of the respirator.
However, in Exposure Study 9, we observed that workers do not normally wear a respirator during shift periods, and that they occasionally wear a dust mask, except for the jet operator and the boring machine worker.
Therefore, no adjustments were made to the use of the respiratory system.
Health checks are carried out on a regular basis per worker, at least once every 3-5 years, including lung capacity measurements.
Additional inspections were carried out on workers considered by the company to be engaged in overexposed work (
That is, the drilling and blasting workers and the spraying workers).
Therefore, the number of workers examined in this study was not equal, and the time period between lung function tests was different.
Four nurses and company doctors have received specialized training in calibration equipment and conducting inspections.
Lung capacity measurement using two bellow lung capacity meters (
Vitalograph S with PFT2 PLUS Printer, Buckingham, United Kingdom).
Calibration and measurement are carried out in accordance with the guidelines recommended by the American Thoracic Society.
The 13 recorded variables are forced lung capacity (FVC)
The amount of forced breath in one second (FEV1).
Using the reference values of the European Coal and Steel Community, lung function variables are expressed as a percentage of absolute and predicted values (ECSC).
There is no good reference data in Norway, so there may be deviations in percentage predictive values.
However, changes in lung function are unlikely to be affected.
The exposure values measured by the data analysis were used for sampling time because they were considered representative of the shift and no further adjustments were made.
Discovery logs best describe exposure data
Normal distribution, so log transformation is used for statistical analysis.
In order to assess whether the workers within the work group are in uniform contact with dust and gas, the Interior (GSDWW)
Between workers (GSDBW)
Geometric standard deviation is estimated.
Variance Component estimation limit maximum likelihood used in random effect variance analysis (REML)
Algorithm, because the number of repeated measurements by workers is not equal.
In order to assess the exposure contrast between the working groups, the group (GSDWG)
Between groups (GSDBG)
Between the workers (GSDBW)
The standard deviation was estimated by the mixed effect model, using REML, with fixed effect in the Operation Group and Random effect 15 in the subjects.
Calculate the contrast of the average exposure level between working groups as described by Kromhout and Heederik: 16 contrast = CTR (lnGSDBG)2/((lnGSDBG)2 + (lnGSDBW)2).
For statistical tests, the significance level is 0. 05 was chosen.
Longitudinal analysis of lung function data was based on first and last observation data for workers who had more than two examinations.
Changes in lung function (ΔFVC and ΔFEV1)
Defined as the difference in lung function between the last observation and the first observation (
Negative values indicate decreased lung function).
Individual lung function changes were assessed by comparing lung function at the first and last observations using a paired t-test.
Because of the small number of them, the TBM workers were excluded from the final analysis ((2)
Only blue collar workers; and (3)age groups (
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