| 摘要: | 目的：本研究透過重覆性測量的研究設計來探討不同強度的職業噪音暴露與不同頻率的噪音對血壓正常勞工及高血壓勞工在動態血壓(包括收縮壓、舒張壓)及心跳速率的影響。
方法：本研究以中台灣某家航空製造業公司員工作為研究對象，進行全廠區現場訪視、均能音量調查及收集現場相關資料。我們先針對噪音暴露較高之廠區利用八音度音頻分析儀作環境噪音採樣，並且進一步對噪音平均值≧90 dBA之工作位置作不同頻率之頻譜分析。我們依據環境噪音採樣結果作相似暴露族群之分類，並且徵求得現場勞工24名(5名高血壓)與93名辦公室勞工(14名高血壓)參與本研究。我們測量參加者在工作日及非工作日24小時的噪音暴露及動態血壓與心跳速率，並且收集員工個人問卷與健康檢查資料作為干擾因子的控制。資料分析以混合式線性迴歸模式來分析不同程度噪音暴露在白天時間(7:30-16:30)、夜晚時間(16:30-23:00)、睡眠時間(23:00-7:30)及24小時平均對於不同分組之動態血壓與心跳速率之影響。
結果：高噪音暴露組(≧80 dBA)相較於血壓正常的辦公室勞工在工作日白天時間、睡眠時間與24小時平均有顯著較高的動態收縮壓(5.14 mmHg，95% CI=0.85-9.43；5.76 mmHg，95% CI=0.61-10.91；3.99 mmHg，95% CI=0.80-7.19)與舒張壓(3.41mmHg，95% CI=0.19-6.63；4.14 mmHg，95% CI=0.19-8.08；2.68 mmHg，95% CI=0.21-5.14)。高血壓勞工相較於非高血壓勞工無論在工作日或非工作日都有顯著較高的24小時動態收縮壓(12.64 mmHg，95% CI=10.30-14.98；10.33 mmHg，95% CI=7.82-12.83)與24小時舒張壓(8.00 mmHg，95% CI=6.26-9.74；7.22 mmHg，95% CI=5.31-9.13)；而且兩組在工作日的動態收縮壓與舒張壓差異明顯大於在非工作日。噪音每上升1分貝會使高血壓勞工在工作日與非工作日24小時平均的即時暴露收縮壓(0.25 mmHg，95% CI=0.15-0.36；0.29 mmHg，95% CI=0.18-0.40)、舒張壓(0.16 mmHg，95% CI=0.09-0.23；0.23 mmHg，95% CI=0.15-0.31)與心跳速率(0.18 beat/min，95% CI=0.12-0.24；0.25 beat/min，95% CI=0.17-0.32)顯著增加，並且持續至60分鐘延遲暴露仍有顯著上升的現象。我們也發現高血壓勞工之收縮壓、舒張壓與心跳速率受到急性噪音暴露的影響會明顯高於非高血壓勞工。此外，1000 Hz之高噪音暴露勞工(≧70 dBA)相較於血壓正常之辦公室勞工在工作日白天時間(4.17 mmHg，95% CI=-0.70-9.04，P=0.092)、睡眠時間(8.44 mmHg，95% CI=3.85-13.02，P=0.0005)與24小時平均(3.33 mmHg，95% CI=-0.27-6.94，P=0.069)有明顯較高的動態收縮壓。噪音每上升1分貝會使1000 Hz之高噪音暴露勞工(≧70 dBA)、1000 Hz之低噪音暴露勞工(<70 dBA)與血壓正常之辦公室勞工在工作日24小時平均的即時暴露收縮壓(0.41 mmHg，95% CI=0.26-0.55；0.16 mmHg，95% CI=0.05-0.27；0.19 mmHg，95% CI=0.13-0.26)、舒張壓(0.26 mmHg，95% CI=0.15-0.36；0.17 mmHg，95% CI=0.09-0.25；0.20 mmHg，95% CI=0.15-0.24)與心跳速率(0.25 beat/min，95% CI=0.16-0.33；0.31 beat/min，95% CI=0.23-0.39；0.15 beat/min，95% CI=0.11-0.19)顯著增加，並且持續至60分鐘延遲暴露仍有顯著上升的現象；我們也發現1000 Hz之高噪音暴露勞工(≧70 dBA)之收縮壓與舒張壓受到急性噪音暴露的影響會明顯高於1000 Hz之低噪音暴露勞工(<70 dBA)與血壓正常之辦公室勞工；而1000 Hz之低噪音暴露勞工(<70 dBA)之心跳速率也會明顯高於血壓正常之辦公室勞工。
結論：職業噪音暴露強度大於80分貝以上會影響航空製造業勞工的動態收縮壓與舒張壓，而且對於高血壓勞工在動態血壓及心跳速率都有顯著較高的影響。此外，1000Hz的噪音暴露可能對勞工的動態血壓及心跳速率有較大的影響。
Objectives:
This repeated-measure study aimed to investigate effects of occupational noise exposure at different intensity and frequencies on ambulatory blood pressure and heart rate among normotensive and hypertensive workers in the aviation industry.
Methods:
We selected an aircraft manufacturing company in Central Taiwan as the study population. We performed the preliminary walk-through survey for environmental noise exposure and measured 8-hr time-weighted-average equivalent sound level at different frequencies in the workplace with noise levels above 90 A-weighted decibel (dBA) . We classified all workers into different similar exposure groups and recruited 24 (5 hypertensive) field workers and 93 (14 hypertensive) officers as study subjects. We measured personal noise exposure, ambulatory blood pressure and heart rate over 24 hours on the working and non-working days. We collected some confounders from health check-ups and self-administered questionnaires. The linear mixed-effects regression models were used to investigate effects of noise exposure on ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) during the daytime (7:30-16:30), nighttime (16:30-23:00), sleep time (23:00-7:30) and over 24 hours between different classified groups.
Results:
Workers exposed to ≥ 80 dBA had significantly higher mean values of ambulatory SBP (5.14 mmHg, 95% CI=0.85-9.43; 5.76 mmHg, 95% CI=0.61-10.91; 3.99 mmHg, 95% CI=0.80-7.19) and DBP (3.41 mmHg, 95% CI=0.19-6.63; 4.14 mmHg, 95% CI=0.19-8.08; 2.68 mmHg, 95% CI=0.21-5.14) than normotensive officers during the daytime, sleep time and 24-hour average on the working day. Hypertensive workers had significantly higher mean values of ambulatory SBP (12.64 mmHg, 95% CI=10.30-14.98; 10.33 mmHg, 95% CI=7.82-12.83) and DBP (8.00 mmHg, 95% CI=6.26-9.74; 7.22 mmHg, 95% CI=5.31-9.13) compared with normotensive ones on both working and non-working days. Such differences between hypertensive and normotensive groups were obviously higher on working day than on the non-working day. Per 1-dBA increase in the 24-hour average noise exposure was significantly associated with transient elevations of SBP (0.25 mmHg, 95% CI=0.15-0.36; 0.29 mmHg, 95% CI=0.18-0.40), DBP (0.16 mmHg, 95% CI=0.09-0.23; 0.23 mmHg, 95% CI=0.15-0.31) and HR (0.18 beat/min, 95% CI=0.12-0.24; 0.25 beat/min, 95% CI=0.17-0.32) among hypertensive workers on both working and non-working days. Such effects on SBP, DBP and HR still persisted at the 60-min time-lagged noise exposure and were more pronounced in hypertensive workers than in normotensive ones. In addition, workers exposed to ≥ 70 dBA at 1000 Hz had obviously higher mean values of ambulatory SBP during the daytime (4.17 mmHg, 95% CI=-0.70-9.04, P=0.092), sleep time (8.44 mmHg, 95% CI=3.85-13.02, P=0.0005) and over 24 hours ( 3.33 mmHg, 95% CI=-0.27-6.94, P=0.069) than normotensive officers on the working day. We also found that per 1-dBA increase in 24-hour average noise exposure among workers exposed to ≥ 70 dBA at 1000 Hz, those exposed to <70 dBA at 1000 Hz and normotensice officers was significantly associated with transient elevations of SBP (0.41 mmHg, 95% CI=0.26-0.55; 0.16 mmHg, 95% CI=0.05-0.27; 0.0.19 mmHg, 95% CI=0.13-0.26), DBP (0.26 mmHg, 95% CI=0.15-0.36; 0.17 mmHg, 95% CI=0.09-0.25; 0.20 mmHg, 95% CI=0.15-0.24) and HR (0.25 beat/min, 95% CI=0.16-0.33; 0.31 beat/min, 95% CI=0.23-0.39; 0.15 beat/min, 95% CI=0.11-0.19) on the working day. Such effects on SBP, DBP and HR still persisted at the 60-min time lagged noise exposure. In addition, workers exposed to ≥ 70 dBA at 1000 Hz had the greatest effects on SBP and DBP as well as those exposed to <70 dBA at 1000 Hz had the highest impact on HR.
Conclusions:
Exposure to occupational noise ≥ 80 dBA may increase ambulatory SBP and DBP in aviation industry workers. Hypertensive workers may be more susceptible to noise exposure than normotensive ones on ambulatory blood pressure and heart rate. Noise exposure at 1000 Hz may have the greatest effects on ambulatory blood pressure and heart rate in workers. |
