Respiratory symptoms and ventilatory functions among quarry workers in Edo state, Nigeria.
Study subjects
Quarry site workers, Ikpeshi community, Edo State, Nigeria
Adult quarry workers aged 18 years and above who had worked in the quarry for at least one year, working in the production area (milling, grinding, breaking and loading of stones). 53.9% had worked in the quarries for 1-5 years; less than a quarter were smokers. Significantly younger than the office-worker controls (p < 0.05). Workers with contraindications to spirometry were excluded.
Descriptive cross-sectional study of quarry workers in Ikpeshi community, Akoko-Edo local government area, Edo State, southern Nigeria
Quarry office workers (controls), Ikpeshi community, Edo State, Nigeria
Adult quarry workers aged 18 years and above who had worked in the quarry for at least one year, working in the administrative offices. 37.8% had worked in the quarries for 1-5 years; less than a quarter were smokers. Significantly older than the site workers and more often married (both p < 0.05). Workers with contraindications to spirometry were excluded.
Descriptive cross-sectional study of quarry workers in Ikpeshi community, Akoko-Edo local government area, Edo State, southern Nigeria
Quarry workers who smoke (site and office groups pooled)
Smokers among the 113 adult quarry workers (both site and office groups); the paper reports only that less than a quarter of respondents in both groups were smokers, without an exact count. All respiratory symptoms assessed were lower among smokers than non-smokers, an association the authors attribute to the small number of smokers.
Descriptive cross-sectional study of quarry workers in Ikpeshi community, Akoko-Edo local government area, Edo State, southern Nigeria
Non-smoking quarry workers (site and office groups pooled)
Non-smokers among the 113 adult quarry workers (both site and office groups); more than three quarters of respondents in both groups were non-smokers, but the paper gives no exact count.
Descriptive cross-sectional study of quarry workers in Ikpeshi community, Akoko-Edo local government area, Edo State, southern Nigeria
Lung function assays
Spirometry - quarry site workers (dust-exposed group)
FEV1 and FVC in the 76 quarry site workers were significantly lower than in the 37 office-worker controls: FEV1 2.77 +/- 0.73 L vs 3.14 +/- 0.78 L (p = 0.02 in the Results body; the abstract rounds this to p < 0.05), FVC 3.48 +/- 0.84 L vs 3.89 +/- 0.92 L (p < 0.05). FEV1/FVC and PEFR were also measured, but their per-group values appear only in Table 3, which is not reproduced in the cached full text, so they are not recorded here. The site workers also had a significantly higher occurrence of chest tightness (35.5% vs 16.2%, p < 0.05); cough (23.7% vs 13.5%), sputum (21.1% vs 16.2%) and dyspnoea (7.9% vs 5.4%) were higher in the exposure group without reaching statistical significance. No dust sampling was carried out, so exposure is recorded as group membership with no concentration.
Exposure conditions
| Condition | Agent | Concentration | Duration |
|---|---|---|---|
| Occupational quarry dust exposure in the production area (milling, grinding, breaking and loading of stones); no dust sampling performed, so no concentration is recorded EXPOSURE:isara-quarry-dust |
dust ENVO:00002008 |
— | — |
Outputs
| Group | Output | Description |
|---|---|---|
| treated | Measured FEV1 and FVC in quarry site workers LF:isara-site-workers-spirometry-output-exposed · under EXPOSURE:isara-quarry-dust |
fev1: 2.77 liter (mean; standard deviation ±0.73 liter; n=76)
fvc: 3.48 liter (mean; standard deviation ±0.84 liter; n=76)
|
Evidence
The mean (SD) FEV1, and FVC were significantly lower among the exposure compared with the control group; 2.77L (0.73) versus 3.14L (0.78), p = 0.02, and 3.48L (0.84) versus 3.89L (0.92), p < 0.05.
States the mean and SD of FEV1 and FVC recorded on this assay's site-worker output and on the companion office-worker assay's output, with the exact p-value for FEV1.
The exposure group had significantly higher occurrence of chest tightness (35.5%) compared with 16.2% of the controls (p < 0.05).
Supports the symptom-prevalence findings carried in this assay's description; chest tightness was the only symptom with a statistically significant excess in the dust-exposed site workers.
Although we did not carry out dust sampling of the site and office environment in this study, it is expected that the level of respirable dust will be higher in the site environment than the office environment.
Justifies recording the quarry-dust exposure condition without a concentration value: the study measured no dust levels, so exposure is group membership only.
Spirometry - quarry office workers (control group)
FEV1 and FVC in the 37 office workers (administrative staff at the same quarries, designated the control group): FEV1 3.14 +/- 0.78 L, FVC 3.89 +/- 0.92 L. The controls were significantly older than the site workers (mean age 42.6 +/- 12.7 vs 36.2 +/- 10.9 years, p < 0.05); note that the age difference runs against the lung-function difference, since FEV1 and FVC decline with age yet the older office group had the higher values. Wheeze (10.8% vs 10.5%) and nasal congestion (27.0% vs 25.0%) were non-significantly higher in this control group.
Exposure conditions
| Condition | Agent | Concentration | Duration |
|---|---|---|---|
| Administrative office environment at the same quarries (control condition; no dust sampling performed) COND:isara-office-environment |
— | — | — |
Outputs
| Group | Output | Description |
|---|---|---|
| control | Measured FEV1 and FVC in quarry office workers LF:isara-office-workers-spirometry-output-control · under COND:isara-office-environment |
fev1: 3.14 liter (mean; standard deviation ±0.78 liter; n=37)
fvc: 3.89 liter (mean; standard deviation ±0.92 liter; n=37)
|
Evidence
The mean (SD) FEV1, and FVC were significantly lower among the exposure compared with the control group; 2.77L (0.73) versus 3.14L (0.78), p = 0.02, and 3.48L (0.84) versus 3.89L (0.92), p < 0.05.
States the control-group mean and SD of FEV1 (3.14 +/- 0.78 L) and FVC (3.89 +/- 0.92 L) recorded on this assay's output.
The controls with a mean age of 42.6 ± 12.7 years were significantly older than the exposure groups with a mean age of 36.2 ± 10.9 years (p < 0.05) and a higher proportion of them were married (p < 0.05).
States the mean age and SD recorded on this assay's study_subject and documents the age imbalance between the two groups.
Spirometry - quarry workers who smoke (both groups pooled)
Among the 113 quarry workers (site and office groups pooled), smokers had significantly lower lung function than non-smokers: FEV1 2.91 +/- 0.77 L vs 3.39 +/- 0.69 L (p = 0.01), FVC 3.61 +/- 0.91 L vs 4.26 +/- 0.74 L (p < 0.05), PEFR 6.56 +/- 2.43 vs 7.98 +/- 1.67 (printed unit L; PEFR is a flow conventionally in L/s or L/min, recorded as printed) (p < 0.05). The paper does not report the number of smokers, only that less than a quarter of respondents in both groups were smokers, so no sample_size is recorded. Smoking was not significantly associated with the prevalence of respiratory symptoms, which the authors attribute to the relatively few smokers identified.
Exposure conditions
| Condition | Agent | Concentration | Duration |
|---|---|---|---|
| Cigarette smoking (self-reported current smoking; no dose or pack-year data reported) EXPOSURE:isara-cigarette-smoking |
smoke ENVO:01000838 |
— | — |
Outputs
| Group | Output | Description |
|---|---|---|
| treated | Measured FEV1, FVC and PEFR in quarry workers who smoke LF:isara-smokers-spirometry-output-smokers · under EXPOSURE:isara-cigarette-smoking |
fev1: 2.91 liter (mean; standard deviation ±0.77 liter)
fvc: 3.61 liter (mean; standard deviation ±0.91 liter)
peak expiratory flow: 6.56 liter (mean; standard deviation ±2.43 liter)
|
Evidence
In both groups, smokers had significantly lower mean (SD) FEV1, FVC and PEFR compared with non-smokers; 2.91L (0.77) versus 3.39L (0.69), p = 0.01, 3.61L (0.91) versus 4.26L (0.74), p < 0.05 and 6.56L (2.43) versus 7.98L (1.67), p < 0.05.
States the mean and SD of FEV1, FVC and PEFR recorded on this assay's smoker output and on the companion non-smoker assay's output, with the exact p-value for FEV1.
Less than quarter of the respondents in both groups were smokers.
Documents why the smoker and non-smoker outputs carry no sample_size: the paper gives only this bound, not the number of smokers.
Spirometry - non-smoking quarry workers (both groups pooled)
Non-smoking quarry workers (site and office groups pooled): FEV1 3.39 +/- 0.69 L, FVC 4.26 +/- 0.74 L, PEFR 7.98 +/- 1.67 (printed unit L; PEFR is a flow conventionally in L/s or L/min, recorded as printed). These are the comparator values for the smoker assay. The paper does not report the number of non-smokers, so no sample_size is recorded.
Exposure conditions
| Condition | Agent | Concentration | Duration |
|---|---|---|---|
| Non-smoking quarry workers (comparator condition for the smoking contrast) COND:isara-nonsmoking |
— | — | — |
Outputs
| Group | Output | Description |
|---|---|---|
| control | Measured FEV1, FVC and PEFR in non-smoking quarry workers LF:isara-nonsmokers-spirometry-output-nonsmokers · under COND:isara-nonsmoking |
fev1: 3.39 liter (mean; standard deviation ±0.69 liter)
fvc: 4.26 liter (mean; standard deviation ±0.74 liter)
peak expiratory flow: 7.98 liter (mean; standard deviation ±1.67 liter)
|
Evidence
In both groups, smokers had significantly lower mean (SD) FEV1, FVC and PEFR compared with non-smokers; 2.91L (0.77) versus 3.39L (0.69), p = 0.01, 3.61L (0.91) versus 4.26L (0.74), p < 0.05 and 6.56L (2.43) versus 7.98L (1.67), p < 0.05.
States the non-smoker mean and SD of FEV1 (3.39 +/- 0.69 L), FVC (4.26 +/- 0.74 L) and PEFR (7.98 +/- 1.67) recorded on this assay's output.
Response comparisons
FEV1 in quarry site workers vs office workers
FEV1 2.77 +/- 0.73 L in site workers vs 3.14 +/- 0.78 L in office workers, p = 0.02 (Results body; the abstract gives p < 0.05). The paper reports no difference value, so change_value is omitted. The control output lives on the office-worker assay.
Statistical test: Student's t-test
FVC in quarry site workers vs office workers
FVC 3.48 +/- 0.84 L in site workers vs 3.89 +/- 0.92 L in office workers, p < 0.05 (a significance threshold, not an exact p-value, so p_value is omitted). The paper reports no difference value, so change_value is omitted. The control output lives on the office-worker assay.
Statistical test: Student's t-test
FEV1 in smoking vs non-smoking quarry workers
FEV1 2.91 +/- 0.77 L in smokers vs 3.39 +/- 0.69 L in non-smokers, p = 0.01, pooled across both worker groups. The paper reports no difference value, so change_value is omitted. The control output lives on the non-smoker assay.
Statistical test: Student's t-test
FVC in smoking vs non-smoking quarry workers
FVC 3.61 +/- 0.91 L in smokers vs 4.26 +/- 0.74 L in non-smokers, p < 0.05 (threshold only, so p_value is omitted), pooled across both worker groups. The paper reports no difference value, so change_value is omitted. The control output lives on the non-smoker assay.
Statistical test: Student's t-test
PEFR in smoking vs non-smoking quarry workers
PEFR 6.56 +/- 2.43 in smokers vs 7.98 +/- 1.67 in non-smokers (printed unit L, recorded as printed), p < 0.05 (threshold only, so p_value is omitted), pooled across both worker groups. The paper reports no difference value, so change_value is omitted. The control output lives on the non-smoker assay.
Statistical test: Student's t-test
Protocols
KoKo Legend spirometry per ATS/ERS 2005 criteria
FEV1, FVC, FEV1/FVC and PEFR measured with a KoKo Legend spirometer (Model 314000, Serial 2007LB0538). A minimum of 3 and a maximum of 8 acceptable and repeatable forced expiratory manoeuvres were done with the study participant seated and upright according to ATS/ERS 2005 criteria. The best test (acceptable curve with the highest sum of FVC and FEV1) was used for interpretation. The spirometer was calibrated daily before the first participant and after the 8th participant or after 4 hours of continuous usage, using a valid certified accurate 3L calibration syringe. Airflow obstruction was defined as FEV1/FVC <70%.
Equipment: KoKo Legend spirometer (Model 314000, Serial 2007LB0538); Certified accurate 3L calibration syringe
Respiratory symptom questionnaire adapted from the BOLD questionnaire
Structured questionnaire adapted from relevant sections of the Burden of Obstructive Lung Diseases (BOLD) questionnaire, administered on the study participants by the researchers. Collected socio-demographic characteristics and respiratory symptoms of interest: cough, sputum, wheezing, chest pain, dyspnoea and nasal congestion.