Environmental monitoring helps you 
keep a controlled facility under control

Environmental Monitoring (E/M) is a program designed to demonstrate the control of viable (living microorganisms) and non-viable particles in critical areas. These areas include cleanrooms, controlled environments, sampling areas, molding equipment, laminar flow hoods, anterooms, and laboratories. Here we’ll address viable monitoring. Viable testing detects and enumerates bacteria, yeast, and mold; it includes the monitoring of personnel, air, and area surfaces.

Companies that have their facilities monitored do so to ensure their desired/required standards are met. The areas that are sampled in a manufacturer’s cleanroom include the air, which is checked on a regular basis (e.g., daily, weekly, quarterly) for particle counts and viable counts; surfaces (including floors, walls, and equipment); and personnel. Personnel monitoring employs contact plates to assess the individuals’ microbial contamination.

There are two methods for air sampling in a cleanroom. In one method, air samplers draw in predetermined volumes of air. The air is drawn over a sterile Petri dish, which is later incubated to reveal the number of viable organisms per cubic meter or liter of air. A second method, called settling plates, involves exposing Petri dishes containing sterile growth media to the environment for a specific period of time, usually between 30 and 60 minutes. Viable microorganisms that settle onto the media surface will grow after the plates are incubated. However, they do not reflect microbial contamination with a measured volume of air.

For surfaces in a cleanroom, there also are two methods to obtain samples. The first involves the use of special Petri dishes, known as contact plates, which contain sterile growth medium prepared in a manner so the surface of the media protrudes above the rim of the plate. The contact plate is pressed against any flat surface that needs to be sampled. Any viable microorganisms will stick to the agar surface and grow upon proper incubation. This technique reveals the number of viable microorganisms on a surface.

The second method makes use of swabs stored in a suitable sterile liquid. The swabs are rubbed over the test surface. A microbiologist can determine the type of microorganisms on the swab by subculturing it to media. Swabs are used for surfaces that are not flat, and can be used to sample hard-to-reach areas of machinery that could not be sampled with a contact plate. Swabbing is more qualitative than quantitative.

Employee monitoring is a good indication of how well personnel are gowning when they enter a cleanroom. Many companies utilize this testing for proficiency-based training programs for cleanroom personnel. Personnel may be monitored for microbial contamination much as surfaces are monitored, with contact plates used to measure contamination on areas of the body that may interact with the sterile field or product exposure areas. These may include gloved hands, forearms, or other areas.

Environmental organisms recovered from manufacturing areas should be identified to show what organisms are present, and what may contaminate a product. Knowing this provides a processor with important information in monitoring and preventing potential contamination pitfalls.

If you don’t keep a record of the microorganisms detected in your facility, you won’t be able to determine over time how effective your cleaning efforts are. Microbial identification is a service to catalog those microorganisms found during monitoring. These “house organisms” provide information on potential contaminants and overall efficacy of a company’s cleaning process. It is important that proper disinfectants are used on a routine basis to keep the level of house organisms in check. A disinfectant study should be implemented to demonstrate the effectiveness of the sanitizers used against house organisms. This effectiveness study exhibits to regulatory agencies that the company is using the correct sanitizer at appropriate dilutions and contact times to combat potential contamination.

Where to sample?
When determining what locations in a cleanroom to sample, a processor needs to consider potential product exposure areas, processing parameters, HEPA locations, equipment design, and validation criteria. The frequency of monitoring depends on product and quality requirements. Sampling frequency may be subject to change depending on trending analysis and changes in equipment, processing, or number of personnel. A sampling plan describing procedures and identifying sample sites, sampling numbers, and sample frequency should be developed. Particle count samples are based on the square root of the cleanroom area in meters. Sampling personnel should be proficient in aseptic technique.

Also, “Alert” and “Action” levels should be established, based on your products. An Alert is an indication that the level of microbial growth may be reaching an undesirable level. If an Action level occurs, disinfection of the area should begin immediately as well as an assessment of what caused the Action level to be reached. Monitoring should be increased until microbial counts return to a desired level.

By proactively establishing and managing a strong environmental monitoring program, plastics processors have better odds at keeping their facilities clean and ultimately at succeeding in the medical device market.

E/M Assoc. Inc. (Salem, NH) is a contract environmental monitoring company serving New England. Edited by Matt Defosse.