Hygiene in the Workspace

We've come a very long way from the early days of hazardous gas detection.

MANKIND has continuously searched for and found evolving means for survival. Gas monitoring instrumentation has been a part of that evolution. In the span of the last 200+ years, the act of monitoring a worker's environment for explosive and toxic gases, as well as for oxygen enrichment or deficiency, has seen a tremendous evolution.

The need to understand which potential hazards existed in the work environment began in the mining industry. Mining applications can present several unseen atmospheric dangers. Explosive gases such as methane and poisonous gases such as nitrogen dioxide and carbon monoxide threaten the lives of miners every day. The presence of toxic gases also can affect oxygen levels. For example, hydrogen sulfide that is heavier than air can force out existing oxygen, bringing the oxygen level to below the absolute minimum safe level of 19.5 percent by volume.

In the 1700s, fire bosses in coal mines would literally use a torch to light off existing methane gas to clear the way for workers to perform their duties. By today's standards, this is not exactly the safest way of clearing the air, especially for the fire boss, but it did clear the air.

Canaries also were taken into mines and utilized as crude gas detection devices. If the bird acted unusually or died, miners would evacuate. The bird would suffer the adverse effects of hazardous gases or decreased oxygen levels before a human body would react because the canary's respiration rate is considerably faster than that of a person. Therefore, the rate at which poison is ingested into the bloodstream, or the rate at which symptoms of asphyxiation set in, is much quicker that that of a human counterpart.

Beginning in 1815, flame safety lamps were introduced to test the atmosphere for the presence of methane and carbon dioxide. These lamps also could detect low oxygen levels in the air. While certainly more advanced than the fire boss's torch or the canary, the flame safety lamp has experienced declining usage as a result of the continued innovation of gas monitoring devices.

Electronics Arrive
As technology advanced and electronics were introduced to the world of gas detection, single- and multi-gas devices that have the capability of monitoring a myriad of toxic and combustible gases, as well as oxygen levels, have evolved. The first electronic single-gas monitors were basic at best. Designed for the coal industry to sniff out methane, these monitors utilized analog readouts to indicate the presence of gas.

Most monitors of today offer considerably more common features, such as a dot matrix display of real-time monitoring data of all installed sensors, powerful audible alarms complemented by vibrating and visual alarms, internal or external sampling pumps that draw samples to the monitor, and much more.

One of the main keys to the progression of gas monitoring equipment centers on their ease of use, in particular relating to the calculation and documentation of data that is collected through industrial hygiene functions. A Merriam-Webster dictionary defines hygiene as "a science of the establishment and maintenance of health." When referring to gas monitoring, hygiene can be defined simply as the science of maintaining the health of the atmosphere in which one works.

In order to maintain the health of a worker's space or atmosphere, you first need to know which hazards may be present. In many cases, the industrial processes will clearly determine the potential hazards. In some cases, the initial screening of an environment is done with sorbent or color-detector tubes as a cost-effective way to analyze the environment. Continuous monitoring in the workspace is put in place after specific hazards are determined. This is where gas-monitoring instruments play a crucial role: in maintaining proper hygiene of an industrial environment.

A monitor utilized primarily for safety purposes alarms when readings of the target gas exceed the pre-determined low alarm settings programmed into the monitor. Alarms also are sounded when the environment becomes oxygen deficient or enriched.

A monitor utilized for hygiene purposes not only has the ability to detect dangerous levels of explosive or toxic gas and monitor the oxygen levels in the atmosphere, but also has the ability to record atmospheric readings of the area's hygiene through a practice called datalogging. Many of today's monitors come equipped with a datalogger, which is a device containing a microprocessor that stores information electronically extracted from an instrument. The instrument can be connected to a computer or other printing device for later reference and printouts.

What type of information do the dataloggers track to ensure proper hygiene of the workspace? The two most important bits of information tracked in a datalogger related specifically to hygiene are STELs and TWAs.

STEL is an acronym for Short Term Exposure Limit. It represents the average of a gas concentration to which a worker has been exposed during a 15-minute period. If this amount exceeds predetermined limits, the worker must remove him/herself from the hazard for a period of at least one hour before re-entry. STEL values may be exceeded only four times during a normal work shift.

TWA is an acronym for Time-Weighted Average. It literally means the average amount of gas to which a worker has been exposed during a given time period. This time is usually defined as eight hours to represent a normal work day. If a predetermined TWA value is exceeded, a worker may not re-enter the workspace for the balance of the work day.

STELs and TWAs are calculated by the datalogger's microprocessor by utilizing guidelines established by the American Conference of Governmental Industrial Hygienists. The guidelines list the maximum concentration of a substance to which a worker may be exposed without ill effects during a normal eight-hour, five-day week.

In addition to STEL and TWA, datalogging typically captures each gas reading, temperature, instrument user ID, site ID, time, and date of sample. This is valuable tracking information the datalogger can provide to safety professionals to maintain accurate records and documentation so they are within safety regulations.

This information is important not only for the immediate health and well-being of workers who may be exposed to atmospheric hazards, but also for having the hygiene information documented so operators can make educated and calculated decisions on how to eliminate gas hazards from the work area and keep it safe for workers. Furthermore, the importance of gas monitoring devices to industrial hygienists and safety professionals is significant. The information that is recorded becomes the impetus for the development of a responsible, OSHA-conforming gas monitoring program.

Other Considerations
Maintenance management is also part of the hygiene function and can be greatly enhanced by taking advantage of even further advances in gas monitoring technology. Today, instrument maintenance can be managed using automated docking systems. Instrument management/docking systems are valuable for many reasons. They can provide the following;

* Automated calibration/bump testing. OSHA mandates in 29 CFR 1910.146 that the only way to detect a hazardous atmosphere safely is with a "Calibrated direct reading instrument." Automated calibration and full docking systems often provide single-button calibration options to help meet the OSHA requirements. Workers no longer have to calibrate their monitors manually.
* Recordkeeping. Docking systems automatically record and store valuable information, such as bump and calibration records, allowing recordkeeping of all hygiene information stored. Datalogging information is logged and stored through the event logging mode, which records information when an incident or event occurs.
* Recharging. Docking systems also can be used to charge monitors when not in use. This will ensure the monitor is fully charged the next time it is used.
* Instrument diagnostics. Automated maintenance systems include technology that provides a means for diagnosing potential problems with your monitor, such as low or marginal sensor life, date of the last calibration, and the number of days until the next calibration is due.

Looking Ahead
The evolution of automated instrument maintenance systems has afforded us the opportunity to utilize two-way wireless and or Ethernet connectivity to link up to 100 stand-alone instrument docking modules from remote locations anywhere in your facility. This connectivity allows information from each station or site to be relayed back to one central database, allowing for total, centralized instrument management.

The need for atmospheric monitoring and the potential hazards has been prevalent for many decades and probably will exist forever. The evolution of electronic gas monitors and their ever-growing capabilities will help to ensure the atmospheric conditions of our work areas remain in good hygiene.

This article appeared in the October 2005 issue of Occupational Health & Safety.

This article originally appeared in the October 2005 issue of Occupational Health & Safety.

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