勞働科学 84巻
84巻 1号
瀬尾明彦，鳥居克紘，土井幸輝
チームリフティングにおける筋骨格系負担
−作業姿勢と足場の高さの違いが作業負荷に与える影響−
労働科学，84（1），６～15，（2008）
本研究は、2人でのチームリフティングにおいて、2人の荷物保持姿勢や足場の高さなどの作業条件が作業者の筋骨格系に及ぼす影響を調べた。その結 果、直立での保持に比べるとしゃがみの保持では腰部負担が高くなることがわかった。また、自分が直立であっても相手がしゃがみ姿勢をとったり相手と足場の 高さが異なったりすると、体幹の前傾は大きくなり、操作力も高くて互いに押し合う方向に変移していた。そのため、同じ姿勢で足場の高さに差がない条件に比 べると、腰部および上肢の負担が高く、荷物の持ちやすさも低下することが明らかになった。
キーワード : 荷物取り扱い作業；チームリフティング；作業姿勢；筋骨格系負担；腰部椎間板圧縮力
Akihiko SEO，Katsuhiro TORII， Kouki DOI
Musculoskeletal Workload During Materials Handling Performed by Team Lifting: Effects of Working Posture and Standing Height on the Workload
THE JOURNAL OF SCIENCE OF LABOUR，84（1），６～15，（2008）
Team lifting is performed when heavy materials handle in limited work spaces and assistive devices. In this study, the effects of differences in working postures and standing height between two lifting members on musculoskeletal workload were investigated. Ten healthy male subjects performed two-person team lifting with a 30 kg box. The working postures of the two lifting members included a "both standing", a "both squatting", and a "pair of standing and squatting". The differences in standing height between the two lifting members were 0 cm, ±20 cm and ±37.5 cm. The effect of standing height was studied only in the "both standing" condition. Working posture, floor reaction force, electromyogram (EMG), and subjective complaints during box holding were recorded. The hand force was estimated by the floor reaction force. The back compression force and joint torque were estimated by 2-dimensional static biomechanical analysis. The results showed that the back compression force and the EMGs of the trapezius and the low back muscles in the "both squatting" were higher than that in the "both standing" posture. In the "pair of standing and squatting" posture, the hand force of the squatting side member was larger than that of standing side member. The back compression force was also larger in the squatting posture than in the standing posture. When the standing height was the same, the subjects held the box by pulling each other. When the standing height was different, the subjects held the box by pushing each other, and the hand force of high-side member was larger than that of the low-side member. The back compression forces in both high- and low-side members were higher than that in the same standing height.
Key Words: Manual materials handling；Team lifting；Working posture；Musculoskeletal load；Back compression force
福原 驍，金原清之，辻 克彦
ブース式フード内の流れ--作業者および作業台が流れに及ぼす影響--
労働科学，84（1），16～24，（2008）
近年、吹出し側に送風機を用いない密閉式プッシュプル型換気装置が局所排気装置と同様に有効な換気装置として認められた。しかし、排風機のみを使用 する水平流による密閉式プッシュプル型換気装置の内部は局所排気装置であるブース式フードと同様である。したがって、従来ブース式フードで指摘されている 問題点は送風機を用いない水平流による密閉式プッシュプル型換気装置についても言えるだろう。今回はブース式フードにおいてブース内に作業者が立ち入った 場合、さらに作業台が置かれた場合について、吸込み側開口部の大きさが作業者の呼吸域近傍の流れにどのような影響を及ぼすかについて数値シミュレーション によって検討し、排風機のみの水平流による密閉式プッシュプル型換気装置についても考察を行った。
キーワード：ブース式フード；局所排気装置；プッシュプル型換気装置；呼吸域；数値シミュレーション
Isamu FUKUHARA, Kiyoyuki KANEHARA ，Katsuhiko TSUJI
Flow in Booth-Type Hoods: Influence of a Worker and A Worktable on the Flow
Flow In Booth Type Hoods−Influence of Worker and Worktable on Flow−
THE JOURNAL OF SCIENCE OF LABOUR，84（1），16～24，（2008）
Recently, a push-pull type ventilation system not using a supply-side fan has been recognized as an effective ventilation system and as a local exhaust system. however, the inside of a push-pull-type ventilation system using only an exhaust fan to generate horizontal airflow is the same as the inside of a booth-type hood functioning as a local exhaust system. Therefore, as regards a push-pull-type ventilation system relying on horizontal flow without a supply fan, there would remain the same problems pointed out with respect to a usual booth-type hood. In this paper, the influence of suction-side opening sizes on the flow in the neighborhood of a worker's breathing zone was investigated by numerical simulations in the cases when a worker entered a booth and when a worktable was additionally set in the booth. Further, the influence of a push-pull-type ventilation system using only an exhaust fan for horizontal flow was discussed.
Key Words: Booth type hood; Local exhaust system; Push- pull ventilation system; Breathing zone; Numerical simulation
松元 俊，佐々木司，崎田マユミ，内藤堅志，青柳直子，高橋悦子，酒井一博
看護師が16時間夜勤時にとる仮眠がその後の疲労感と睡眠に及ぼす影響
労働科学，84（1），25～29，（2008）
本研究は，看護師が16時間夜勤時にとる仮眠がその後の疲労感と睡眠に及ぼす影響を調べた。記録なしを除く仮眠取得は100%であった。夜勤中に保 障された2時間かそれ以上の仮眠取得群（≧120群）と，2時間未満の仮眠取得群（＜120群）に分けて解析した。その結果，群間では，夜勤開始から夜勤 明けの夜眠後までの疲労感，昼眠と夜眠の睡眠時間，就床時刻に差はみられなかった。また，両群とも夜勤後の昼眠取得は100%であったが，疲労感は夜眠後 まで回復しなかった。≧120群では＜120群より，夜勤中の忙しさが低く，休憩時間が長い傾向があった。そのため，16時間夜勤での疲労回復には仮眠時 間保障だけでなく負担軽減などの調整も必要であると考えられた。
キーワード：仮眠；16時間夜勤；看護師；疲労感；昼眠
Shun MATSUMOTO, Tsukasa SASAKI, Mayumi SAKITA, Kenshi NAITO, Naoko AOYAGI, Etsuko TAKAHASHI, Kazuhiro SAKAI
The Effects of the Naps Taken by Hospital Nurses in 16-hour NightShifts on their Subjective Fatigue Feelings and Subsequent Sleeps
THE JOURNAL OF SCIENCE OF LABOUR，84（1），25～29，（2008）
The effects of naps taken by hospital nurses during 16h nightshifts on subjective fatigue feelings and following sleeps were studied. Twenty-two hospital nurses with the mean age of 29.1 completed sleep logs and reported fatigue feelings and business at work by means of visual analog scales as well as resting periods during their shifts. The results were compared between those who took a nap of 120 min or more guaranteed by the hospital and those who took a nap of less than 120 min during a nightshift. The levels of fatigue feelings, day and night sleeps and the start times of naps were not significantly different between the two groups. The group of nurses with a nap of 120 min or more reported lower levels of business at work and longer resting periods than those with a nap of less than 120 min. Therefore, the two-hour nap was not considered enough to facilitate recovery from fatigue due to a 16h nightshift. These results pointed out the need to improve working conditions including arrangements about work load during the long-hour nightshifts. The day sleep following the nightshift was short in both the groups, whereas the fatigue from the nightshifts did not recover before the subsequent night sleep. Further studies were suggested necessary to examine the influence on sleep of different daily life activities associated with gender differences.
Key Words: Night time nap；16h nightshifts；Hospital nurse；Subjective fatigue feelings； Day sleep
84巻 2号
吉川 徹，長須美和子，松田文子，水野有希，上野満雄，酒井一博
清掃労働者における腰痛の訴えと腰痛に関連した欠勤状況
労働科学，84（2），33～42，（2008）
清掃職場における腰痛の訴え(腰痛有訴率)と腰痛に関連した欠勤状況を明らかにするため，全国自治体職場の清掃職員6,675名と事務職員 1,200名を対象に自記式質問紙調査を行った。調査は2005年11月から2006年1月に実施した。清掃職員5,046名(有効回答率75.6%)と 事務職員 725名(有効回答率60.7％)の回答のうち，腰痛の訴えは清掃職員には68.8%(3,550名/4,866名)，事務職員には51.1%(365名 /712名)に認められた。腰痛既往のある対象者のうち，調査日から遡って過去一年間に腰痛を理由として欠勤を経験した者(以下，腰痛による欠勤経験者) は，清掃職員では29.0％ (1,062名/3,657名)，事務職員では15.8% (63名/398名)に認められた。事務職員と清掃職員の腰痛による欠勤経験の有無に関する性・年齢調整後オッズ比は1.95(95%信頼区間 1.43-2.66)であった。一方，腰痛による欠勤経験者のうち，清掃職員による欠勤の内容(複数回答)は，「有給休暇の利用」が77.5％(836名 /1,062名)と最も多く，「病気休暇の利用」は27.7％(294名/1,062名)，「公務災害として欠勤」5.6％(60名/1,062名)で あった。清掃事業における腰痛は依然として欠勤の大きな理由であり，清掃事業運営における労務管理上，腰痛対策を適切に講じることが重要と確認された。ま た，腰痛経験者の中に，療養の際に公務災害としてではなく有給休暇を利用したものが多かったことから，疾病の罹患状況に鑑みた腰痛の業務上認定の基準や公 務災害認定･労働災害補償制度の運用制度の見直しなどの検討を行っていく余地があると考えられた。
キーワード: 清掃作業従事者；作業関連性腰痛；有訴率；欠勤；労働災害補償
Toru YOSHIKAWA， Miwako NAGASU，Fumiko MATSUDA,Yuki MIZUNO, Mitsuo UENO， Kazuhiro SAKAI
Prevalence Rates of Low Back Pain and Sick Leaves Related to it Among Municipal Garbage Collection Workers in Japan
THE JOURNAL OF SCIENCE OF LABOUR，84（２），33～42，（2008）
The prevalence rates of low back pain and sick leaves related to low back pain among municipal garbage collection workers in Japan were studied. Replies to a unanimous questionnaire were collected from 6,675 garbage collection workers and 1,200 clerical workers in selected municipality offices during a period from November 2005 to January 2006. The rate of those having experienced low back pain during a one-month period among 5,046 garbage collection workers (valid response rate 75.6%) and 725 clerical workers (valid response rate 60.7%) was 68.8%(3550/4866) and latter was 51.1%(365/712) respectively. Those who had experienced absence from work due to low back pain during the past one-year period accounted for 29.0% (1,062/3,657) among the garbage collection workers and 15.8%(63/398) among the clerical workers. Moreover, the odds ratio of garbage collection workers concerning the absence rate due to low back pain was 1.95 (95% confidence interval 1.43-2.66) compared clerical officers with the age and sex adjustment. About the means of taking absence related the low back pain those who used paid leaves accounted for 77.5 % ( 836/1,062), while those who used official sick leaves accounted for 27.7 % (294/1,062) and those who resorted to the workers compensation scheme accounted for 5.6 %( 60/1,062). The absence rate of the garbage collection workers was higher than that of the clerical workers. It was found important to take appropriate preventive measures within the personnel management of these workers. It was suggested by the results that it was necessary to review the criteria for recognition of work-related low back pain. A range of preventive measures were suggested to reduce the absence rates due to low back pain.
Key words: Garbage collection workers；Work-related low back pain；Prevalence rate； Sick leaves；Workersﾕcompensation
奥村隆志，細田 聡，施 桂栄，余村朋樹，井上枝一郎，村上保夫
一専門病院における安全文化レベル評価に関する調査研究
−安全文化評価ツールを用いて−
労働科学，84（2），43～61，（2008）
本研究では152床を有する心臓循環器の専門病院（総従業員数は301名）の安全文化を調査し，組織内の潜在リスク把握を目的とした。調査に用い た安全文化評価ツールは10分野，36項目からなり，安全の仕組みに対して共通志向を有しているかを従業員が相互評価するものである。結果，全般的に従業 員の相互の評価に大きな差が生じていた。具体的には，「不具合処理」，「情報経路・コミュニケーション」，「作業条件」の3分野は評定値得点，共有性得点 とも平均値に比べ有意に低く，改善すべき優先度の高いのはこれらの分野である。中でも，「意思疎通能力」，「ボトムアップ経路」，「環境条件の把握」， 「現場実態の把握」の4項目は対策が望まれる結果であった。ただし，医師に対しては上記の内容に留まらず，広範囲の分野，項目で評価が低く，非常に大きな 認識の差が生じており，安全に対して医師の行動や態度に問題があると組織全体として認識していた。
キーワード：安全文化；安全文化評価ツール；潜在リスク；質問紙調査；病院
Takashi OKUMURA, Satoshi HOSODA, Guirong SHI,Tomoki YOMURA, Shiichiro INOUE,Yasuo MURAKAMI
A Study on the Safety Culture Level at a Specialty Hospital by Means of a Safety Culture Assessment Tool
THE JOURNAL OF SCIENCE OF LABOUR，84（２），43～61，（2008）
With the aim of understanding organizational factors related to human error, we investigated the safety culture of a specific organization using a safety culture assessment tool. This tool was used to characterize the mutual differences between three layers of a managers, supervisors and workforces. The investigation was carried out at a special hospital with 152 beds applying heart circulation machines. The tool was effective to characterize the organization with notable differences among mutual evaluations. The three categories of "trouble-shooting", "information channels and communication" and "work environment" had evaluations below the average levels, and were thus considered a high priority for improvement. Further, compared with average levels, the results for the items "communication", "bottom-up channel", "controlling environmental conditions" and "controlling spot conditions" were evaluated to be important, indicating an acute need for taking immediate measures. For core physicians, however, evaluation results were low not only for the three categories and the four items mentioned above but also for a wide range of other variables, with remarkable differences in recognition in each layer. This was recognized as an issue affecting the whole organization since the problem in physiciansﾕ actions or attitudes was crucial for safety.
Key words：Safety culture ； Safety culture assessment Tool ； Potential risk ； Questionnaire survey ； Hospital
堀口俊一，寺本敬子，西尾久英，林 千代
「児科雑誌」に発表された仮称所謂脳膜炎（鉛毒性脳症）に関する研究の足跡（１）
平井毓太郎による究明まで
労働科学，84（2），62～71，（2008）
幼児の仮称所謂脳膜炎の原因は明治時代から大正時代の終わりにかけて原因不明であった。1923年，平井毓太郎によって，その原因が母親の使用す る含鉛白粉によることが確認されるまで，約30年間に多くの研究がなされた。著者らは所謂脳膜炎の名称が初めて現れた児科雑誌第3号（1895年）から， 平井が原因を確認した第281号（1923）までの間に発表された57編について，その発表形式，発表内容によって分類するとともに，初めて所謂脳膜炎の 名称と解説がなされた2編，該脳膜炎の診断に重要な所見を指摘した報告5編，該脳膜炎の統計的観察の報告1編，唯一の小児鉛中毒の報告1編，平井による原 因確認の初めての報告，計10編について考察した。これらの研究のユニークな足跡から，中毒を引き起こす因子として日常の生活行動を綿密に観察することの 重要性が示された。
キーワード：鉛中毒；鉛毒性脳症；仮称所謂脳膜炎；平井毓太郎；児科雑誌
Shunﾕichi HORIGUCHI， Keiko TERAMOTO，Hisahide NISHO，Chiyo HAYASH
Development of Studies on So-called Meningitis (Lead Encephalopathy) Reported in Acta Paediatrica Japonica and Leading to the Confirmation of the Cause of the Meningitis by Ikutarou Hirai
THE JOURNAL OF SCIENCE OF LABOUR，84（２），62～71，（2008）
The cause of "so-called meningitis named tentatively" of infants was not clarified for a long period in our country from the middle of the Meiji Era (1868～1912) until the end of the Taisyo Era (1912～1926). Many studies on the so-called meningitis had been presented for about 30 years until Ikutarou Hirai confirmed in 1923 that the meningitis was caused by lead-containing face powder being used by mothers. A survey on 57 reports relating to the so-called meningitis published in ﾒJika-zasshiﾓ (Acta Paediatrica Japonica) was conducted from No. 3 in 1895 that carried the first report of the so-called meningitis to No. 281 in 1923 that published Hiraiﾕs report confirming the cause of the meningitis. According to the form of publication in the journal, these 57 reports were classified into 18 original papers, 5 speeches presented at meetings, 25 abstracts of papers presented in meetings and 9 abstracts from other domestic journals. Through examining the contents of the reports, these reports were classified into six categories: 12 review papers, 27 papers on clinical examinations, 4 on clinical pathology, 6 on clinical symptoms, 6 on case reports and 2 on statistical observations. Among the 57 reports, special consideration was given to the following ten reports: two reports on naming and explaining the so-called meningitis for the first time, five reports indicating findings important for the diagnosis of the meningitis, one report on the statistical observations of the meningitis, one report on the sole lead poisoning case of an infant and lastly Hiraiﾕs first report confirming the cause of the so-called meningitis. The unique development of these studies demonstrated the importance of close observations of daily life activities as causative factors of poisonings.
Key words: Lead poisoning; Lead encephalopathy; So-called meningitis named tentatively; Ikutarou Hirai; "Zika-zasshi"( Acta Paediatrica Japonica)
84巻 3号
鈴木安名
専属産業医の選任義務のない法人における人事担当者によるメンタルヘルス施策立案
労働科学，84(3), 75～88，(2008)
専属産業医の選任義務のない１部上場企業２社，１部上場企業の関連会社６社と1省庁の人事担当者を調査対象者として，メンタルヘルス施策を立案す るために必要な条件を検討した。実際に施策立案がなされるように，行政の指針等にもとづいた講義と討論による教育実践を行い，施策立案にかかわる条件をヒ アリング調査した。安全配慮義務の法的な認識と業務実態把握の方法に違いを認め，結果として立案された施策は数と内容に大きな差があった。専属産業医の選 任義務のない法人で，人事担当者がメンタルヘルス対策を立案するためには，安全配慮義務が雇用契約における債務として理解され，適切な形で業務実態が把握 される事が重要と考えられた。
キーワード：メンタルヘルス対策；人事担当者；嘱託産業医；安全配慮義務；産業教育
Yasuna SUZUKI
Planning of Mental Health Measures by Personnel Management Staff Members in Corporations Served by Part-Time Occupational Physicians
THE JOURNAL OF SCIENCE OF LABOUR，84(3), 75～88，(2008)
Procedures required for personnel management staff members in planning mental health measures for corporations served by part-time occupational physicians were investigated. Existing planning processes of mental health measures were studied in two publicly quoted companies, five affiliated companies and a ministry with a focus on roles of personnel management staff members. The discussion by these members following a lecture were referred to. Differences were noted among the workplaces studied in engaging part-time physicians in dealing appropriately with individual cases. The recognition of the corporate obligations for securing safety and health at work, provision of mental health care for employees in need, rehabilitation procedures and coordination with attending physicians were considered important. The particular roles of personnel managers in workplaces without full-time occupational physicians were emphasized. It was considered necessary to establish practical mental health support measures in these workplaces and train personnel managers about their planning.
Key words：Mental health care；Personnel management staff members；Part-time industrial physicians；Duty to care for safety；Industrial education
宮本直和，白土男女幸，濱田明美，飯 聡，西村由二三，仲井朝美，芳田哲也
包丁研ぎ動作の技術習得に関する筋電図学的考察
労働科学，84(3), 89～98，(2008)
未熟練者の技術習得過程おける包丁研ぎ動作の変化について，3次元動作解析や筋電図，および研ぎ上がった包丁の刃先形状を縦断的に測定して検討し た。包丁研ぎの練習期間が進行すると一研ぎにおける動作時間が短く腰および膝の変位量が大きくなったが，動作の再現性は低かった。また尺側手根屈筋の筋活 動が大きくなり，さらに包丁を押し出す際の拮抗筋である上腕二頭筋の活動は2日目，1週間目では見られたが3週間目では消失した。研ぎ上がった包丁の刃先 形状は 3週間後においてのみ凹凸形状になった。以上のごとく，技術習得過程における包丁研ぎ動作や筋活動は顕著に変化し，それらは刃先形状の凹凸形成に影響して いる可能性が示唆された。
キーワード：刃；動作解析；形状評価；筋活動；トレーニング
Naokazu MIYAMOTO, Minayuki SHIRATO, Akemi HAMADA, Akira II, Yoshifumi NISHIMURA, Asami NAKAI, Tetsuya YOSHIDA
A kinematic and electromyographic study of skill acquisition for sharpening a Japanese kitchen knife
THE JOURNAL OF SCIENCE OF LABOUR，84(3), 89～98，(2008)
The purpose of this study was to investigate the process in which a beginner acquired skill for sharpening a Japanese kitchen knife during three weeks of training. The surface electromyograms (EMG) were recorded from: the flexor carpi ulnaris (FCU), biceps brachii (BB), triceps brachii (TB) and deltoid posterior (DP) of both upper limbs, and body motion was captured by four digital video cameras during sharpening of a knife by a beginner. Furthermore, knife edge shapes were examined microscopically before and after sharpening. Measurements were performed immediately after the first training day (N1), the following day (N2) and one (N3) and three (N4) weeks later. The motion duration per each stroke of sharpening became shorter, while the reproducibility of the motion duration and motion range per each stroke declined in proportion to the duration of training. The trajectory length of the hip and knee during one stroke became longer. With regard to EMG, the activities of FCU during one stroke became larger and steadier. From N2 and onward the EMG activities of DP appeared during the pulling phase of sharpening motion and the amplitude of DP gradually increased during the training period. Additionally, the EMG activities of BB and TB, which were an antagonist and an agonist of the elbow extension, respectively, were observed during the pushing phase at N2 and N3, while the EMG of BB disappeared it N4. The roughness of edges at the front and central region sharpened by a beginner were greater at N4 than at N1, N2, and N3. These results suggest that the whole body motion and muscle activities of the upper limbs for sharpening a kitchen knife change during beginner training, and that those changes may relate to the increase in the roughness of knife edges.
Key words：Knife edge； Motion analysis； Shape evaluation；Muscle activity； Training
佐々木司，久保智英
時短勤務中に発症した"Karoh-Shogai"事例における時間外労働時間
労働科学，84(3), 99～104，(2008)
過労障害（脳出血）を呈した時短勤務中のホワイトカラー労働者の発症前時間外労働時間を検討した。時間外労働時間は発症3ヵ月前，またそれは休日 に増大した。発症1ヵ月前の増大は，脳･心臓疾患の労災認定基準（2001）に踏襲した。一方，発症1週間前では増大は示されなかった。また本事例の発症 は，基礎疾病としての高血圧，育児の過重負担，育児時間に挿入される時間外労働時間の増大が，三位一体のプロセスによるものと考えられた。本知見は，今後 ワーク・ライフバランスの名の下に男性管理職の育児参加，育児中の女性労働者の管理職登用，さらには中高年労働者の介護の際に，時短勤務下であっても適切 な労働時間管理の必要性を示唆するものである。
Tsukasa SASAKI , Tomohide KUBO
Hours of Actual Overtime Worked in a Karoh-shogai Case Developing Despite Reduced Work Hours
THE JOURNAL OF SCIENCE OF LABOUR，84(3), 99～104，(2008)
In this paper, we studied working conditions, especially actual hours of overtime worked, for a white-collar worker for whom left putamen hemorrhaging (1 cc) was suffered on July 13, 2006.This allowed us to calculate hours of overtime worked over the six-month period leading up to the onset of the case, as specified in standards applicable to industrial accidents reported in 2001 involving cerebral and cardiac diseases. As results, the total monthly hours of overtime worked in the three months preceding to the onset were 87.6, 43.8 and 85.8, respectively, rising above 100 to 135.0，135.2 and 141.1 hours from three months before the onset. The hours of overtime worked on the holidays for each of the three months was remarkably high, before the onset were 90.7，93.5 and 80.5 hours. The result was consistent with the standards defining industrial injuries involving cerebral and cardiac diseases adopted in 2001, which state that hours of overtime worked generally should have increased in the month prior to the onset. However, hours of overtime worked during the week before the onset was 14.3 hours, and the lowest weekly total for any of the four weeks leading up to the onset.
Therefore, this suggests that the mechanism leading to the findings in our study is ﾔtrinityﾕ as the progression of three separate factors: hypertension childcare burdens, and hours of overtime spilling over into childcare time. Although our findings involve a case in which hypertension was the underlying disease, this onset pattern may recur in future cases in which young white-collar workers, in pursuit of the ideal work-life balance, face the increased burdens of childcare alongside work; or when women in their child-rearing years face increased workloads following promotion to an administrative position. Since an earlier study appears to indicate that numbers of hours worked is a poor index of cardiovascular health, we will further analyze Victim Aﾕs workload and over-fatigue status.
Key words： Karoh-shogai (over fatigue disorder)； White-collar worker； Overtime work； Left putamen hemorrhaging；Reduced work hours
84巻 4号
久保智英，佐々木司，松元 俊
ノルマによる心理的ストレスが連続睡眠短縮夜とその後の回復夜の睡眠構築に及ぼす影響
労働科学，84(4), 119～128，(2008)
本研究は，課題にノルマを与えた際の心理的ストレスが10日間の連続睡眠短縮夜とその後4日間の回復夜の睡眠構築に与える影響を検討した。課題を 達成した群（達成群）と達成できなかった群（非達成群）に分けて比較した結果，睡眠効率，SWS，S2，%SWS，S2には条件間に有意差は検出されな かったが，REM潜時とREMS（分），%REMSに有意差がみられた。またSOREMpも非達成群に多く観察された。とりわけ，非達成群のREM潜時は 睡眠短縮夜を終えても，もとの水準に回復しなかった。本研究より，ノルマによる心理的ストレスの影響はREM睡眠変数に影響する事が示唆された。
キーワード：心理的ストレス；過労死；REM睡眠；連続睡眠短縮；ノルマ
Tomohide KUBO，Tsukasa SASAKI，Shun MATSUMOTO
Impact of Psychological Stress Due to Assigned Task on Sleep Architecture Under the Condition of Repeated Sleep Restriction and Subsequent Recovery
THE JOURNAL OF SCIENCE OF LABOUR，84(4), 119～128，(2008)
The purpose of this study was to examine the impact of psychological stress on sleep architecture under the condition of sleep restriction with assigned tasks and subsequent restoration periods. Male participants (N=16; mean age; 27.3, range; 19 - 38) were required to attend a laboratory for sixteen consecutive nights for recording their performance under the following conditions: adaptation night (A; 23：00-7:00), baseline night (B; 23：00-7:00), sleep restriction night 1-10 (SR1-SR10; 01：00-6:00) and recovery night 1-4 (R1-R4; 23：00-7:00). The data of four participants were, however, excluded from the analysis because of technical failures. To expose the participants to psychological stress due to assigned tasks, they were required to complete English transcription tasks by SR10. We informed the participants we would not pay compensation (255,000 yen) at all if they could not complete the assigned tasks in time. Therefore, the psychological stress in this study was mainly due to the factors of assigned tasks. However, we paid the compensation regardless of their achievement at the end of the experiment. sleep architecture was evaluated by sleep efficiency, %S2, %SWS, %REM sleep and REM sleep latency. To reveal the impact of the psychological stress on sleep architecture, we classified all variables into the completed group (N=6) and the non-completed group (N=6), according to the achievement of the tasks.
Most characteristic findings in this study were the variables of REM sleep. To sum up, we observed shorter REM sleep latency and greater REM sleep (in minutes), %REM sleep in the non-completed group compared with the Completed group (REM sleep latency; F1,10=5.957, p=0.035, REM sleep; F1,10=7.736, p=0.019, %REM sleep; F1,10=13.054, p=0.005, respectively). It should be noted that participants in the non-completed group had difficulty in recovering from the impact of psychological stress, and had not recovered by the fourth night of recovery sleep. In summary, the results suggested that psychological stress in this study had an impact on the expression of REM sleep.
Key words：Psychological stress； Karoshi (Death due to over-fatigue)； Rapid eye movement sleep； Repeated sleep restriction； Assigned task
木村康寛, 和久直樹, 高島 充, 大川井宏明
座位継続時における居眠りと空気動圧センサーによる体動波の出現周期･活動量の関連
労働科学，84(4), 129～139，(2008)
現在，車や電車の居眠り運転が社会問題となっており，居眠り運転は重大な事故を引き起こす。そこで本研究は，座位における居眠りと活動様態の関連 に注目し，座面空気動圧センサー(エム・アイ・ラボ)による無拘束・無装着の生体計測手法を用いて，座位継続中に生じる体動波様態の推移を調査した。その 結果，居眠りをした場合には，移動RMS値が初期値の10～30％に低下した。この低下は居眠り時前も居眠り時にも現われた。これに対して，「居眠りな し」の例では25％以上を維持した。
キーワ−ド：居眠り予兆；空気動圧センサー；無拘束計測；体動波；座位
Yasuhiro KIMURA , Naoki WAKU, Mitｓuru TAKASHIMA, Hiroaki OKAWAI
Evaluation of the Dozing-off Level During Prolonged Sitting by Means of Quantitative Measurement of Body Motion and its Periodicity Using a Dynamic Air Pressure Sensor
THE JOURNAL OF SCIENCE OF LABOUR，84(4), 129～139，(2008)
Recently, the drowsy state leading to dozing off driving during car driving has been a social problem because of a traffic accidents induced. In the present study, we investigated body motion wave (BMW) changes during 90-minute sitting by using a non-restraint, non-attachment measurement system with a dynamic air pressure sensor. As a result, in dozing case, it was found that the moving root mean square value of the body motion wave decreased by 10-30 percent with reference to that of the baseline level. Such decrease appeared in both before and during drowse/dozing off. On the other hand, the above value in non-dozing case kept greater than 25 percent.
Key words：Prediction of Dozing off ；Dynamic air pressure sensor；Non-restraint measurement；Body motion wave(BMW)；Sitting position
福田宇志
踏切における歩行者・自転車利用者のリスクテイキング行動--警報時間の影響--
労働科学，84(4), 140～150，(2008)
リスクテイキング行動を生じさせる警報時間の影響を明らかにしようとした。降りきった遮断機をくぐって渡り始めた歩行者・自転車利用者は２名見ら れたが，踏切の直前に着くやいなや降りきった遮断機をくぐって渡り始めていた。警報が鳴り始めてから遮断機が降り始めるまでの期間の歩行者・自転車利用者 の横断実行率は90％以上(90.5～100％)と非常に高かったが，遮断機が降り始めてから遮断機が降りきるまでの期間では4.7～36.8％低 い，63.2～90.0％であった。遮断動作後の横断実行率を合計警報時間が長い朝時間帯と短い昼時間帯で比較すると，朝時間帯のほうが6.0～ 14.6％横断実行率が高かった。また，朝時間帯においては，通勤・通学途中の歩行者・自転車利用者が多かったことが示唆されており，これらの結果は，警 報時間や利用場面に起因する時間的なデメリットはリスクテイキング行動の動機となるという予想と一致していた。
キーワード：踏切警報時間の影響；リスクテイキング行動；歩行者・自転車利用者；利用場面；時間的なデメリット
Takayuki FUKUDA
Risk-Taking Behaviour of Pedestrians and Cyclistsat Railroad Crossings--The Effects of Warning Time--
THE JOURNAL OF SCIENCE OF LABOUR，84(4), 140～150，(2008)
The effects of warning time on risk-taking behaviour of pedestrians and cyclists at rail crossings were examined. A total of 457 pedestrians and cyclists were observed at three railroad crossings. One pedestrian and one cyclist started to cross the rails after the rail gates were already closed. Both of them had just arrived within one meter of the railroad crossings when they started to cross rails going around the closed gates. We considered that to restrain such people from crossing dangerously, devices clearly showing the approaching degree of a train should be installed. The rates of pedestrians and cyclists, who started to cross the rails after the bells started to ring but before the gates were already closed, were compared between the morning home when there was a long warning time and the daytime hours when the warning time was short. Over 90% of pedestrians and cyclists started to cross the rails before the gates started to close. These ratios decreased to 63.2_90.0% after the gates started to close. The rates of those crossing after the gates started to close during the morning hours were higher than those during the daytime hours: 6.0_14.6%. In the morning, if people would not started to cross the rails after the warning, they would have to wait for a long time until the gates were opened again, and they would then have to hurry on to get to work or get to school on time. Therefore, these results confirmed our expectation that time disadvantages caused by long warning times and their circumstances of using rail crossings motivated risk-taking behaviour.
Key Words：The effects of warning time of railroad crossings；Risk-taking behaviour；Pedestrians and cyclists；Circumstances of usage；Time disadvantages
永田久雄
第11次労働災害防止計画と数値目標の意義
労働科学，84(4), 151～157，(2008)
第11次労働災害防止5ヵ年計画に記載されている労働災害の死傷者数を減少させるための数値目標について検証した。その結果，予測される死傷者数 の減少率よりかなり高い数値目標となっていることを，過去の災害統計値から推計した。計画内容を検証した結果，数値目標を達成する上で優先して実施すべき 死傷者件数の多い転倒災害について，具体的な道筋について言及していない。このことから，数値目標を達成するのが困難であることを指摘した。労働災害防止 計画に，数値目標を記載することは不可欠であり，5年間で1,000億円を超える労働安全衛生対策事業費の運用にあたっても，数値目標といった物さしの導 入を図り事業の評価などを行う必要性について論じた。
キーワード: 労働災害；労働災害防止計画；転倒；数値目標；高年齢労働者
Hisao NAGATA（Ph.D.）
The 11th Industrial Accident Prevention Plan and the Significance of Numerical Targets
THE JOURNAL OF SCIENCE OF LABOUR，84(4), 151～157，(2008)
The numerical targets to decrease occupational accidents within the 5 year-period described in the 11th Industrial Accident Prevention Plan have been analyzed, using approximated curves. As a result of the analysis, the numerical targets are significantly higher than the values predicted from the past occupational accident-statistics. The contents of the plan have been reviewed, and there are no specified measures to prevent most frequently occurring accidents, such as falls on the same level, which should be given priority in order to fulfill numerical targets. It is suggested that the numerical targets are indispensable to assess the level of achievement of the Industrial Accident Prevention Plan and the various expenditures of a huge budget for the Occupational Safety and Health Measures. This budget exceeds 100 billion yen over the five-year duration of this plan, and should be reevaluated for the purpose of attaining the stipulated numerical values.
Key Words: Industrial accident； Prevention plan； Fall； Numerical target； Elderly worker