Laminar Air Flow in The Forensic Science Laboratory

Laminar air flow devices play an important role in forensic science, both to prevent contamination of evidence and to protect the staff and environment. Whether you need a class 1 safety cabinet for the safe handling of human blood and sera, or a laminar flow hood to protect crucial evidence, we at Contained Air Solutions Ltd (CAS) have a product to match.

Forensic science covers more scientific areas than any other discipline. Key areas include toxicology, serology, DNA typing, analysis of trace evidence, fingerprinting, forensic chemistry and forensic geology. Experimental equipment varies between departments, but includes devices for safe containment and handling of hazardous materials, as well as analytical equipment. A typical forensics lab may feature one or more of the following devices:

– Chemical fume cupboard

– Downdraft table

– Laminar flow hood (LFH)

– Robotic enclosure

– Class 1 safety cabinet

– A class 3 cabinet (also called a glove box), for maximum containment

– Evidence drying cabinet. Similar to a recirculating class 2 cabinet, samples are dried in a secure ventilated environment, and the air recirculated into the room through an HEPA filter

– HEPA-filtered fingerprinting cabinet

Laminar air flow for human and environmental protection:

Many forensic investigations involve materials hazardous to human health. Forensic biologists, for example, routinely handle blood and other fluids which potentially carry infectious microorganisms – including those responsible for tuberculosis, HIV and Hepatitis B and C. The risk extends to objects stained with the fluid, such as clothing.

Since it is essential that any evidence brought into the lab is not contaminated in any way, a class 2 biosafety cabinet is the preferred method of containment. Protection is offered in a number of ways:

1. A protective air curtain at the front of the device acts as a barrier between the inside and outside environment, preventing hazardous particles from escaping.

2. The air curtain also prevents contamination of the samples, aided by a downward inflow of HEPA-filtered air.

3. The air passes across the work zone in a unidirectional flow, thus avoiding cross-contamination of evidence.

4. Finally, air is exhausted from the cabinet through HEPA filters, thus protecting the environment. The air may be recirculated back into the room, or exhausted from the lab via a thimble connection. The cabinet can also be hard ducted and exhausted via the building management system.

Further notes on laminar air flow in the forensic laboratory

The HEPA filters on BSCs effectively remove both biological particulates and their associated odors. However, they offer poor protection against toxic or volatile chemicals. Minute quantities of certain chemicals are allowed, providing the cabinet is not exhausted into the room while personnel are present. Flammable or explosive chemicals, which often feature in forensic investigations, pose a particular risk in recirculating BSCs, as the build-up of fumes can lead to a fire or explosion.

Many forensic biologists work at BSL-2 (biological safety level 2), using a class 1 or 2 laminar flow hood. However, certain investigations take place under BSL-3 conditions, using a class 3 biosafety cabinet. An example of this would be mail that has been deliberately infected with a dangerous pathogen such as anthrax.

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