Ventilation: Are Science Labs Really Supposed to Smell?
(Article #9)

One of the topics often mentioned relative to safety concerns is that of ventilation in school science laboratories. Too many school science laboratories have inappropriate and ineffective ventilation systems to take care of the removal of hazardous chemical vapors/fumes. The bottom line is that teachers, students and supervisors can be exposed to poor indoor air quality which can have negative implications on learning and health.

The OSHA Laboratory Standard (CFR #1910.1450) requires that the employer develop a Chemical Hygiene Plan, which will satisfy a number of requirements, including ventilation. In order to meet these ventilation requirements, the plan needs to address the following components of effective ventilation:

1. General laboratory ventilation must be provided by a system which serves as a source of breathing air that is continuously replaced (usually 4-12 times/hours can be adequate). This approach effectively prevents the increase of air concentrations of toxic substances during the working day. In addition, the supply of such air must be from non-laboratory areas and return out to the exterior of the building. The general ventilation system can not be relied on for protection from toxic substances released into the laboratory during its use.

2. Laboratory hoods are to be used only to exhaust the air volume in the hood space, not the laboratory! Supply make up air for the hood may come from the laboratory room or a special supply vent to the hood, depending on the design and capabilities of the room ventilation system. Hood face velocity should be typically 60-100 LFM.

3. Other local ventilation devices need to be incorporated as warranted. For example, a flammable liquid storage cabinet placed in a room with limited or no ventilation will need to be directly vented to the exterior of the building. A chemical storeroom needs to be directly vented to the exterior of the building, although the supply must come from non-laboratory areas. Special note of caution is the storeroom ventilation needs to operate year round to prevent vapor/fume build-up, especially during the summer months.

Evaluation of ventilation should be done when installed and regularly monitored (about every 3 months) or, whenever there is a change made in the local ventilation system.

Criteria for selection of chemicals need to include the capabilities of the ventilation system.

The key to effective ventilation is a Chemical Hygiene Plan that addresses the needs of your school laboratories. During an OSHA inspection by a compliance officer, the school's Hygiene Plan is the bible or employer's expectation! Design the plan based on appropriate OSHA and ASHRAE standards. It will help to insure the safety of students and school employees in the short and long term. If employees believe there is a ventilation problem, they need to register their concern with the district's chemical hygiene officer. In turn, the hygiene officer must share these concerns with the superintendent of schools. OSHA's Laboratory Standard is unique in that it was the first standard to charge the CEO or superintendent of schools in this case, with direct responsibility for implementing, monitoring and rectifying problems concerned with school science laboratories.

(SafeSciTraining990427)

LIVE LONG AND PROSPER WITH SAFETY!

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Dr. Ken Roy
K-12 Director of Science & Safety & authorized OSHA instructor
c/o Glastonbury Public Schools
Glastonbury, CT 06033-3099
Fax 860-652-7275
E-Mail: royk@glastonburyus.org