G. Scott Earnest

Health effects and occupational exposures among office workers near the World Trade Center disaster site.

The extent of health effects and exposure to environmental contaminants among workers and residents indirectly affected by the September 11, 2001, attack on the World Trade Center (WTC) is unknown. The objective of this study was to evaluate concerns related to health effects and occupational exposures three months after the WTC disaster among a population of employees working in a building close to the disaster site. A cross-sectional questionnaire survey was performed of Federal employees working near the WTC site in New York City (NYC) and a comparison group of Federal employees in Dallas, Texas. An industrial hygiene evaluation of the NYC workplace was conducted. Constitutional and mental health symptoms were reported more frequently among workers in NYC compared to those in Dallas; level of social support was inversely related to prevalence of mental health symptoms. Post-September 11th counseling services were utilized to a greater degree among workers in NYC, while utilization of other types of medical services did not differ significantly between the groups. No occupational exposures to substances at concentrations that would explain the reported constitutional symptoms were found; however, we were unable to assess potential occupational exposures in the time immediately after the WTC disaster. There is no evidence of ongoing hazardous exposure to airborne contaminants among the workers surveyed. Specific causes of reported constitutional health symptoms have not been determined. Health care providers and management and employee groups should be aware of the need to address mental health issues as well as constitutional symptoms among the large number of workers in the NYC area who have been indirectly affected by the WTC disaster.

A Control Technology Evaluation of State-of-the-Art, Perchloroethylene Dry-Cleaning Machines

NIOSH researchers evaluated the ability of fifth-generation dry-cleaning machines to control occupational exposure to perchloroethylene (PERC). Use of these machines is mandated in some countries; however, less than 1 percent of all U.S. shops have them. A study was conducted at a U.S. dry-cleaning shop where two fifth-generation machines were used. Both machines had a refrigerated condenser as a primary control and a carbon adsorber as a secondary control to recover PERC vapors during the dry cycle. These machines were designed to lower the PERC concentration in the cylinder at the end of the dry cycle to below 290 ppm. A single-beam infrared photometer continuously monitors the PERC concentration in the machine cylinder, and a door interlock prevents opening until the concentration is below 290 ppm. Personal breathing zone air samples were measured for the machine operator and presser. The operator had time-weighted average (TWA) PERC exposures that were less than 2 ppm. Highest exposures occurred during loading and unloading the machine and when performing routine machine maintenance. All presser samples were below the limit of detection. Real-time video exposure monitoring showed that the operator had peak exposures near 160 ppm during loading and unloading the machine (below the OSHA maximum of 300 ppm). This exposure (160 ppm) is an order of magnitude lower than exposures with more traditional machines that are widely used in the United States. The evaluated machines were very effective at reducing TWA PERC exposures as well as peak exposures that occur during machine loading and unloading. State-of-the-art dry-cleaning machines equipped with refrigerated condensers, carbon adsorbers, drum monitors, and door interlocks can provide substantially better protection than more traditional machines that are widely used in the United States.

Airborne Infection Isolation Rooms – A Review of Experimental Studies

Ventilation guidelines for airborne infection isolation rooms (AIIRs) are highly variable in different countries indicating lack of actual knowledge about the guidance needed. However, US guidelines for AIIRs are extensive and have been widely adopted outside the US. AIIR performance has also been evaluated in numerous studies. For a long time, the aim has mainly been to evaluate how well the existing AIIRs meet US guidelines. For historical reasons, mixing-type ventilation has been emphasised and attention has been paid to air exchange rates, although the use of auxiliary devices, such as portable room-air cleaners and ultraviolet germicidal irradiation systems, has also been examined. Recently, the scope of the investigations has been widened. The most crucial issue is to minimise the potential for disease transmission and prevent the escape of contaminated air from the AIIR. Airflow direction inside the AIIR is also important and AIIRs minimise air leakage to save energy. On the other hand, it has been observed that efficient containment can be achieved even by using simple and inexpensive construction by considering pressure differential and air flow patterns. Nevertheless, additional research is needed to assist hospitals with improving their preparedness to cope with the threat of pandemics by building and using effective AIIRs.

An evaluation of an engineering control to prevent carbon monoxide poisonings of individuals on and around houseboats

From 1990 to 2000, a total of 111 carbon monoxide (CO) poisonings occurred on Lake Powell near the Arizona and Utah border. Seventy-four of the poisonings occurred on houseboats, and 64 were attributable to generator exhaust alone. Seven of the 74 houseboat-related CO poisonings resulted in death. Although many of the reported CO poisonings occurred to members of the general public, some poisonings involved workers performing houseboat maintenance. The National Institute for Occupational Safety and Health evaluated an engineering control retrofitted to a houseboat gasoline-powered generator to reduce the hazard of CO poisoning from the exhaust. The control consisted of a water separator and a 17-foot exhaust stack that extended 9 feet above the upper deck of the houseboat. When compared to a houseboat having no engineering controls, study results showed that the exhaust stack provides a dramatically safer environment to individuals on or near the houseboat. CO concentrations were reduced by 10 times or more at numerous locations on the houseboat. Average CO concentrations near the rear swim deck of the houseboat, an area where occupants frequently congregate, were reduced from an average of 606.6 ppm to 2.85 ppm, a reduction greater than 99%. CO concentrations were also reduced on the upper deck of the houseboat. Hazardous CO concentration in the confined area beneath the near swim deck were eliminated. Based on the results of this study, it is clear that houseboats having gasoline-powered generators that have been outfitted from the factory or retrofitted with an exhaust stack that extends well above the upper deck of the boat will greatly reduce the hazard of CO poisoning.

An Evaluation of Retrofit Engineering Control Interventions to Reduce Perchloroethylene Exposures in Commercial Dry-Cleaning Shops

Real-time monitoring was used to evaluate the ability of engineering control devices retrofitted on two existing dry-cleaning machines to reduce worker exposures to perchloroethylene. In one dry-cleaning shop, a refrigerated condenser was installed on a machine that had a water-cooled condenser to reduce the air temperature, improve vapor recovery, and lower exposures. In a second shop, a carbon adsorber was retrofitted on a machine to adsorb residual perchloroethylene not collected by the existing refrigerated condenser to improve vapor recovery and reduce exposures. Both controls were successful at reducing the perchloroethylene exposures of the dry-cleaning machine operator. Real-time monitoring was performed to evaluate how the engineering controls affected exposures during loading and unloading the dry-cleaning machine, a task generally considered to account for the highest exposures. The real-time monitoring showed that dramatic reductions occurred in exposures during loading and unloading of the dry-cleaning machine due to the engineering controls. Peak operator exposures during loading and unloading were reduced by 60 percent in the shop that had a refrigerated condenser installed on the dry-cleaning machine and 92 percent in the shop that had a carbon adsorber installed. Although loading and unloading exposures were dramatically reduced, drops in full-shift time-weighted average (TWA) exposures were less dramatic. TWA exposures to perchloroethylene, as measured by conventional air sampling, showed smaller reductions in operator exposures of 28 percent or less. Differences between exposure results from real-time and conventional air sampling very likely resulted from other uncontrolled sources of exposure, differences in shop general ventilation before and after the control was installed, relatively small sample sizes, and experimental variability inherent in field research. Although there were some difficulties and complications with installation and maintenance of the engineering controls, this study showed that retrofitting engineering controls may be a feasible option for some dry-cleaning shop owners to reduce worker exposures to perchloroethylene. By installing retrofit controls, a dry-cleaning facility can reduce exposures, in some cases dramatically, and bring operators into compliance with the Occupational Safety and Health Administration (OSHA) peak exposure limit of 300 ppm. Retrofit engineering controls are also likely to enable many dry-cleaning workers to lower their overall personal TWA exposures to perchloroethylene.

A Summary of Research and Progress on Carbon Monoxide Exposure Control Solutions on Houseboats

Investigations of carbon monoxide (CO-related poisonings and deaths on houseboats were conducted by the Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health. These investigations measured hazardous CO concentrations on and around houseboats that utilize gasoline-powered generators. Engineering control devices were developed and tested to mitigate this deadly hazard. CO emissions were measured using various sampling techniques which included exhaust emission analyzers, detector tubes, evacuated containers (grab air samples analyzed by a gas chromatograph), and direct-reading CO monitors. CO results on houseboats equipped with gasoline-powered generators without emission controls indicated hazardous CO concentrations exceeding immediately dangerous to life and health (IDLH) levels in potentially occupied areas of the houseboat. Air sample results on houseboats that were equipped with engineering controls to remove the hazard were highly effective and reduced CO levels by over 98% in potentially occupied areas. The engineering control devices used to reduce the hazardous CO emissions from gasoline-powered generators on houseboats were extremely effective at reducing CO concentrations to safe levels in potentially occupied areas on the houseboats and are now beginning to be widely used.

Carbon Monoxide Emissions from Marine Outboard Engines

Carbon Monoxide (CO) has become a pressing issue for the recreational marine industry. An increasing number of boating incidents have been linked to CO poisoning caused by emissions from gasoline-powered marine engines. Measurements by the National Institute for Occupational Safety and Health (NIOSH) and the U.S. Coast Guard have confirmed potentially hazardous CO concentrations near many of these engines. The measurements have also shown much lower CO concentrations for Evinrude® two-strbke direct-injected engines. This paper reviews national and international CO emission regulations for marine engines and discusses CO formation and reduction mechanisms. The differences between homogeneous- and stratified-charge combustion systems on CO formation, resulting from design and calibration criteria, are analyzed. The primary driving factors for CO formation under high-load homogeneous operation are driven by a desire to maximize power output and a necessity to control the thermal loading of internal engine components. Part throttle and low-load operation are largely driven by emissions and run-quality requirements. Several distinct advantages for direct-injected engines lead to the formation of significantly lower CO concentrations in the exhaust. The unavoidable over-scavenging of air aids in diluting cylinder-out CO levels. This, combined with high exhaust gas temperatures, can generate a significant post-oxidation effect. The post-oxidation effect was investigated in detail and some engine test results are presented. Stratified operation at low loads with high air-fuel ratios result in CO concentrations up to 100 times less than homogeneous-charge engines.

The new ANSI nail gun standard: A lost opportunity for safety

Pneumatic nail guns have been shown in published studies to cause injury and death to both workers and consumers, but those equipped with sequential trigger mechanisms provide much greater safety protection against unintentional discharge than those equipped with contact triggers. In 2015 the American National Standards Institute (ANSI) approved a revision to its 2002 nail gun standard, but failed to require sequential triggers. Substantive and procedural deficiencies in the ANSI standards development process resulted in a scientifically unsound nail gun safety standard, detracting from its use as the basis for a mandatory national safety standard and ultimately from its ability to protect worker and consumer users. Am. J. Ind. Med. 60:147-151, 2017.