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Lab Safety: Environmental Monitoring

Lab safety is an important area of concern for many companies.  Terry Jo Gile, knows lab safety and we are pleased that she will be providing lab safety articles to improve your safety culture.

Certain areas of the laboratory may require ongoing environmental monitoring.  There are many products in the marketplace and selecting the right one for a particular work area may be a daunting task.  A decision for the type of exposure monitoring device must balance risk, cost and work flow efficiency.  In some facilities, the engineering department may have an environmental health and safety technician responsible for monitoring the entire facility.  Other institutions may hire an outside firm to do the monitoring.  Whether you do it yourself or hire an outside firm, you need to understand the types of tools available and their intended use.

Diffusion tubes can be used to determine either a time weighted average (TWA) over an eight-hour shift or a short term exposure limit (STEL) over a 15-minute period. The glass tube has a chemical reagent impregnated in a silica layer. Diffusion detector tubes meet OSHA guidelines for air sampling but they are not the most accurate method.

Vapor monitor badges work by the principle of diffusion. Each worker clips a badge to his or her lab coat collar and records the exposure time, temperature, relative humidity, date exposed, employee name, and monitor number. This information is needed to calculate the exposure level correctly. The badges can be used to determine an eight-hour TWA or a 15-minute STEL.

Some vapor monitor badges are sold with a prepaid analysis. After the badge has been worn, return it in a preaddressed mailer supplied by the manufacturer to be analyzed. Badges produce more accurate results than diffusion tubes, but they cost more, and the lab must wait for analysis results.

Personal air sampling pumps are more difficult to use. A small pump pulls a constant amount of air through a charcoal tube or filter cassette. Personal sampling pumps require calibration before each use and must have the flow rate set to the correct level depending on what is being monitored. The pump is worn near the worker’s breathing zone for the entire day. Once the day is finished, the charcoal tube or filter cassette is sent to the environmental monitoring laboratory of choice to be analyzed. Results from personal sampling pumps are usually more accurate than from other methods, but using them is more cumbersome than other sampling methods.

Detector tube and pump systems are a very effective way to perform on-the-spot air monitoring. They are accurate enough to get an idea of the hazards in the workplace. Detector tubes are typically used when surveying an area and also can give an idea of worker exposure in either ppm or percent by volume. Two main types of pumps are available: piston and bellows. The piston style requires the user to pull a piston to pull air through the tube. With the bellows style, the user squeezes the bellows and, upon release, air is pulled through the tube as the bellows opens. The tubes are relatively inexpensive for quick monitoring, but they are limited in the types of chemicals they can pick up. Check with the vendor to be sure the tube you select can identify the chemical you wish to detect.

Continuous handheld monitors come in a variety of shapes and sizes. They can vary from a relatively simple single-gas monitor to a complex data-logging four-gas monitor. They all make a quantitative analysis that is displayed on a digital or analog readout. The monitors also give real-time readout of the gas concentration at that time. Most handheld meters also have a visible or audible alarm, or both, that will alert the user if a gas is above a safe level. Compared with other types of monitors these are often more expensive and are seldom used in a clinical laboratory setting.

Monitoring is usually conducted annually unless the last permissible exposure limit (PEL) monitoring results revealed employee exposure at or above the action level or STEL.   In that event, repeat employee monitoring every six months until the monitoring results fall below the action level or STEL for two consecutive sampling periods.  When an employee reports signs and symptoms of respiratory or dermal conditions associated with exposure, be sure to monitor the affected employee’s exposure promptly.

Management must review the monitoring results as soon as possible, and never more than 15 days after receiving them. The supervisor must discuss the results with each monitored employee individually, and the results can be posted with the names blacked out. When the PEL is over the action level or STEL, a written plan to reduce exposure to each employee must be provided. The plan must describe corrective actions being taken to decrease exposure. This may include the use of administrative controls such as job rotation to lessen the exposure time to any one employee, the use of engineering controls such as special ventilation to eliminate the overexposure, or personal protective equipment (PPE) such as a respirator for employees to wear. The written plan outlines what the lab is going to do for employees exposed to a chemical over the action level and how this exposure will be monitored.

Written and provide to Safety Topics by: Terry Jo Gile, MT(ASCP)MA Ed. the Safety Lady®


Best-selling author, professional speaker and safety consultant Terry Jo Gile, MT(ASCP)MA Ed., the Safety Lady®, has helped thousands of laboratorians create safety savvy laboratories.  Her book, Complete Guide to Laboratory Safety – Third Edition, is considered the consummate safety reference tool that is specific for clinical laboratories.

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