A long-term study of the development of N2O controls at a pediatric dental facility.

A review is given of National Institute for Occupational Safety and Health (NIOSH) efforts to control N2O at a pediatric dental operatory from 1978 to the present. Measurements of N2O concentrations were made on four occasions before and after installation of different controls, using an infrared analyzer. Air velocity and volumetric flow measurements also were taken, Video imaging was done in some cases simultaneously with real-time N2O measurements to correlate work practices with exposure data. An infrared imaging system was used to identify sources of N2O. Critical components of resulting recommendations for control include monitoring of N2O concentrations; use of engineering controls, such as a scavenging mask, an effective dilution ventilation system, and auxiliary exhaust; good work practices; maintenance of the equipment; and worker education. Data presented strongly supports the hypothesis that better implementation of controls leads to reduction of N2O exposures. N2O concentrations were reduced by a factor of 61 from their initial levels. The current NIOSH recommended exposure limit of 25 ppm TWA during the time of N2O administration appears to be achievable.

Matchmakers' "phossy jaw" eradicated.

Diseases that have been eradicated by worldwide action are rare. Rarer still are examples of occupational diseases that have been eradicated. Phosphorus necrosis, also known as "phossy jaw," was associated with the manufacture of matches. International action to overcome this disease was seen as necessary so that one nation would not have a competitive advantage over another resulting from the elimination of white phosphorous in the manufacture of matches. In the United States the tax power of the federal government was used as the control measure. Following passage of the Match Act of 1912 by Congress, the United States joined other nations in eliminating the dreaded disease, phossy jaw, from its population.

Occupational risk factors associated with soft tissue disorders of the shoulder: a review of recent investigations in the literature.

Cumulative trauma illness currently accounts for over half of all occupational illness in the United States. From 1987 to 1989 there was a 100% increase in the reported number of cases of cumulative trauma illness (Bureau of Labor Statistics 1990). Shoulder region pain ranks second only to low back and neck pain in clinical frequency, and the occurrence of occupational shoulder illness is on the rise. This paper summarizes findings of a subset of recent epidemiologic, laboratory, and field studies conducted in order to identify occupational risk factors for cumulative trauma disorders (CTDs) of the shoulder region. These studies have identified the following risk factors as being associated with particular shoulder pain syndromes: awkward or static postures, heavy work, direct load bearing, repetitive arm movements, working with hands above shoulder height, and lack of rest. The paper begins with a discussion of several shoulder disorders, includes problems in studying cumulative trauma, presents results of recent studies, and concludes with suggested ergonomic controls that could help to reduce the incidence of shoulder disorders, by eliminating or reducing exposure to the associated risk factors.

Understanding and evaluating manual handling injuries: NIOSH research studies.

This paper presents an overview of NIOSH research aimed at characterizing and identifying intervention strategies for reducing musculoskeletal injuries during manual handling activities. Surveillance and evaluative research projects are reviewed. Future research directions of the Institute are also discussed.

Noise in multiple-workstation open-plan computer rooms: measurements and annoyance.

Computers in the workplace have become very prevalent. As with the introduction of any new technology, unanticipated problems often develop. Noise in open-plan computer rooms and annoyance and perceived deterioration in performance associated with it also appears to be a problem that may be similarly categorized. An experimental investigation was undertaken as a result of frequent user complaints about the difficulty of concentrating and performing their work in the computer rooms of a large service organization. Two typical computer rooms were investigated. Noise levels were measured at random times during the working hours. The noise spectrum was found to be almost similar in both facilities. The 10-second A-weighted noise level for all frequencies ranged between 53 and 62 dB. Most noise energy was either in the high-frequency bands (above 2,000 Hz) or low-frequency bands (below 500 Hz). The highest noise energy levels were recorded at 8,000 Hz (between 64 and 73 dB). Least noise energy levels were recorded between 500 and 2,000 Hz (between 35 and 44 dB). The noise spectrum, thus, was substantially different from those of open-plan offices. Eighty-nine percent of the users questioned indicated their tasks required concentration. Fifty percent of all respondents rated the noise level between extremely annoying and unbearable and intolerable (scale values between 22 and 25 on a 25-point scale; 1 being noticeable but not objectionable and 25 being unbearable and intolerable); 10% of the respondents considered the noise very annoying; 20% of the respondents considered the noise levels moderately annoying; the remaining respondents did not seem to have a major problem. Conversational sound and computer-printer beeping sounds were reported to be most annoying by 90% of the respondents who considered the noise levels annoying. Constant arrival and departure of users, sound from keyboards, and ventilation equipment also appeared to be major contributing factors.

Fatal abuse of nitrous oxide in the workplace.

Abuse of nitrous oxide (N2O) while on the job caused at least 11 deaths in 1984 to 1987, as found in investigations by the Occupational Safety and Health Administration and in reports to the Consumer Product Safety Commission. Although nitrous oxide has had a reputation as a "clean and safe" analgesic and anesthetic, the possibility of asphyxiation by inhalation is not widely recognized, and there are no requirements for warning labels on nonmedical sources of N2O. The 11 deaths involved recreational inhalation of N2O by young male employees from tanks or cylinders normally used for legitimate business purposes. In six cases, the victims worked in food serving establishments and inhaled N2O that was used to power whipped cream dispensers. Commercial users of N2O, particularly in the restaurant industry, should be aware of this hazard. Warning labels for N2O sources and tighter control over supplies are warranted.