Alan Hedge

Work-related illness in offices: A proposed model of the “sick building syndrome”

Abstract A nationwide survey of 4 373 office workers at 47 office sites was conducted to assess the prevalence of the sick building syndrome and to investigate associated factors. The office buildings sampled included those ventilated by either natural, mechanical, or forced air, or by air conditioning or some form of comfort cooling, including fan-coil, induction, and constant or variable air volume systems. Results showed a higher prevalence of reports of work-related symptoms of dry eyes, dry throut, stuffy/congested nose, itchy/watery eyes, runny nose, lethargy/tiredness, and headache in air conditioned buildings than in unconditioned buildings. Symptom prevalence was higher in buildings ventilated with water-based cooling systems, e.g., fan-coil or induction systems, than in buildings with all-air systems. A significant relationship was found between the type of humidification used in air-conditioned buildings (none, evaporative/spray, or steam) and the prevalence of itchy eyes, stuffy nose, lethargy, breathing difficulty, and chest tightness. Results also suggest that the “sick building syndrome” is associated with a variety of individual characteristics (sex, age), occupational factors (job type, length of video display unit use, occupancy duration in building, job stress), architectural features (type of office, type of building ventilation system), and psychological processes (perceived environmental control, perceived ambient conditions, perceived environmental satisfaction). A path analytic model is presented that suggests that psychological processes mediate the association between individual, occupational, and environmental characteristics and reports of the “sick building syndrome”.

Effects of keyboard tray geometry on upper body posture and comfort

The effects of a downward-tilting (DT) keyboard tray on wrist posture, seated posture and self-assessed musculoskeletal discomfort were investigated in a field experiment. Thirty-eight professional office workers were studied. A pretest assessed how they typed using either a conventional keyboard on a desk or on an articulating keyboard tray, and with or without wrist rests. Workers were randomly allocated to a control (n = 15) or test group (n = 23) that used their existing keyboard in a DT system. A post-test was conducted 3 weeks later. Results showed no significant changes in wrist posture, seated posture or reports of musculoskeletal discomfort for the control group, and approximately 50% of typing wrist movements put the hand in a neutral zone. There were significant improvements in wrist posture, seated posture and upper body musculoskeletal discomfort for the test group using the DT system. Over 80% of typing wrist movements put the hand into a neutral zone with the DT arrangement. Reactions to using a conventional keyboard on a DT system were positive.

The sedentary office: an expert statement on the growing case for change towards better health and productivity

An international group of experts convened to provide guidance for employers to promote the avoidance of prolonged periods of sedentary work. The set of recommendations was developed from the totality of the current evidence, including long-term epidemiological studies and interventional studies of getting workers to stand and/or move more frequently. The evidence was ranked in quality using the four levels of the American College of Sports Medicine. The derived guidance is as follows: for those occupations which are predominantly desk based, workers should aim to initially progress towards accumulating 2 h/day of standing and light activity (light walking) during working hours, eventually progressing to a total accumulation of 4 h/day (prorated to part-time hours). To achieve this, seated-based work should be regularly broken up with standing-based work, the use of sit–stand desks, or the taking of short active standing breaks. Along with other health promotion goals (improved nutrition, reducing alcohol, smoking and stress), companies should also promote among their staff that prolonged sitting, aggregated from work and in leisure time, may significantly and independently increase the risk of cardiometabolic diseases and premature mortality. It is appreciated that these recommendations should be interpreted in relation to the evidence from which they were derived, largely observational and retrospective studies, or short-term interventional studies showing acute cardiometabolic changes. While longer term intervention studies are required, the level of consistent evidence accumulated to date, and the public health context of rising chronic diseases, suggest initial guidelines are justified. We hope these guidelines stimulate future research, and that greater precision will be possible within future iterations.

Multi-Touch: A New Tactile 2-D Gesture Interface for Human-Computer Interaction

The naturalness and variety of a touch-based hand gesture interface offers new opportunities for human-computer interaction. Using a new type of capacitive sensor array, a Multi-Touch Surface (MTS) can be created that is not limited in size, that can be presented in many configurations, that is robust under a variety of environmental operating conditions, and that is very thin. Typing and gesture recognition built into the Multi-Touch Surface allow users to type and perform bilateral gestures on the same surface area and in a smaller footprint than is required by current keyboard and mouse technologies. The present approach interprets asynchronous touches on the surface as conventional single-finger typing, while motions initiated by chords are interpreted as pointing, clicking, gesture commands, or hand resting. This approach requires learning only a few new chords for graphical manipulation, rather than a vocabulary of new chords for typing the whole alphabet. Graphical manipulation seems a better use of chords in todays computing environment.

Wrist postures while keyboarding: effects of a negative slope keyboard system and full motion forearm supports

Video-motion analysis was used to analyse hand/wrist posture for subjects typing at a 101-key QWERTY keyboard on a 68 cm high worksurface. Three conditions were tested: subjects typed at the keyboard without arm support, subjects typed with adjustable full motion forearm supports, and subjects typed with an adjustable negative slope keyboard support system. The average declination of the negative slope keyboard support chosen by subjects was 12 degrees below horizontal, which flattened the angle of the key tops. Ulnar deviation was comparable in all conditions and averaged 13 degrees for the right hand and 15 degrees for the left hand. Full motion forearm supports did not significantly affect any postural measures. Dorsal wrist extension averaged 13 degrees when typing with or without the full motion forearm supports, but this was reduced to an average -1 degree with the use of the negative slope keyboard support system. Subjects chose to sit at a distance of 79 cm from the computer screen when using the negative slope keyboard system compared with 69 cm without this.

Effects of lensed-indirect and parabolic lighting on the satisfaction, visual health, and productivity of office workers.

A pre- and post-renovation survey evaluated the reactions of office workers to two office lighting systems: a parabolic downlighting system and a ceiling suspended, lensed-indirect uplighting system. Questionnaire data on work content, perception of ambient environmental conditions (including office lighting), work-related health symptoms, job stress, job satisfaction, and self-reported productivity, and environmental data on illumination, air temperature, and relative humidity were collected. The lensed-indirect lighting system was more favourably rated on several subjective lighting impressions scales, and for computer work workers reported fewer screen glare problems, and fewer and less frequent problems with tired eyes and eye focusing. Productivity was less hindered by the lensed-indirect lighting, and satisfaction with office lighting and ratings of lighting quality were significantly higher for this system. These reactions were not associated with any differences in levels of illumination between the lighting systems. Ratings of lighting satisfaction and lighting importance were inversely related. Overall, some two-thirds of workers indicated a preference for working under the lensed-indirect lighting system.

The Effect of Computer Workstation Design on Student Posture

AbstractAlthough the use of computers in the classroom is increasing, little attention has been paid by educators, furniture manufacturers, or researchers to the ergonomic design issues of educational furniture for computer use. Children in the sixth and eighth grades performed keyboarding and mousing tasks at two different computer workstations; one a traditional desktop arrangement, and the second a station that consisted of an adjustable keyboard. Overall student posture scores improved, as measured by the Rapid Upper Limb Assessment, at the adjustable workstation.

Where are we in understanding the effects of where we are

This paper briefly reviews research studies of interest to environmental ergonomists. It includes some recent work on the health effects of office lighting, especially the effects of daylighting, fluorescent lighting and full-spectrum lighting. It also covers studies of indoor air quality in offices, especially investigations of localized air filtration and the sick building syndrome. It argues the value of a systematic, ergonomics approach to designing the built environment.

The sedentary office: a growing case for change towards better health and productivity. Expert statement commissioned by Public Health England and the Active Working Community Interest Company

An international group of experts convened to provide guidance for employers to promote the avoidance of prolonged periods of sedentary work. The set of recommendations was developed from the totality of the current evidence, including long-term epidemiological studies and interventional studies of getting workers to stand and/or move more frequently. The evidence was ranked in quality using the four levels of the American College of Sports Medicine. The derived guidance is as follows: for those occupations which are predominantly desk based, workers should aim to initially progress towards accumulating 2 h/day of standing and light activity (light walking) during working hours, eventually progressing to a total accumulation of 4 h/day (prorated to part-time hours). To achieve this, seated-based work should be regularly broken up with standing-based work, the use of sit–stand desks, or the taking of short active standing breaks. Along with other health promotion goals (improved nutrition, reducing alcohol, smoking and stress), companies should also promote among their staff that prolonged sitting, aggregated from work and in leisure time, may significantly and independently increase the risk of cardiometabolic diseases and premature mortality. It is appreciated that these recommendations should be interpreted in relation to the evidence from which they were derived, largely observational and retrospective studies, or short-term interventional studies showing acute cardiometabolic changes. While longer term intervention studies are required, the level of consistent evidence accumulated to date, and the public health context of rising chronic diseases, suggest initial guidelines are justified. We hope these guidelines stimulate future research, and that greater precision will be possible within future iterations.

Indoor air quality and health in two office buildings with different ventilation systems

Abstract Measurements of indoor air pollutants were taken in (1) an air conditioned and (2) an adjacent, naturally ventilated office of a public sector organization. Self-administered questionnaires on the work environment and health were distributed to all workers. No differences in concentrations of carbon monoxide, carbon dioxide, ozone, and total oxidants were found between buildings. Concentrations of formaldehyde, volatile organic compounds, and respirable particulates were higher in the air conditioned offices. Symptoms of sleepiness, nasal irritation, concentration difficulties, cold/flu-like symptoms, and eye focusing problems were significantly more prevalent in the air conditioned offices. Symptoms of sleepiness, nasal irritation, concentration more prevalent among women than men. Passive smoking was associated with symptom prevalence, but alcohol, tea, and coffee consumption was unrelated. No significant correlations between pollutant concentrations and symptom prevalence were found, however, recalled reports of leaving work early because of feeling ill were significantly correlated with formaldehyde levels in the air conditioned building.