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Environmental Health & Safety


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  2. OSHA requires the use of engineering controls to prevent exposures to laboratory employees. Although Section XVI provides information on local exhaust ventilation systems that can be used for hazardous chemicals, general ventilation is also required for locations where chemicals are stored and used. The following lists the required general ventilation needed in laboratory locations.

    1. Regulations on Ventilation Rates
    2. Ventilation rates for laboratories at the University are required to comply with the Mechanical Code of New York State (Section 401), NFPA-45, and OSHA 29CFR1910.1450.  Unfortunately, the ventilation rates varies significantly and does not take into account that labs with higher ceilings require additional air volumes to achieve the same air changes per hour or obstructions and other factors reduce the effective ventilation rates. Labs for the 21st Century (Labs21) provides good practice strategies to assist in optimizing laboratory ventilation. As stated in their publication, the concept “more is better” – that increased ventilation rates will provide an increase in safety, worker comfort, and research productivity –  is NOT the case. The best practices utilize local exhaust systems and optimizing the general ventilation.

      The table below lists references for laboratory ventilation rates:

      Air Changes Per hour (ACH)
        OSHA Lab   Standard   29CFR1910.1450   4-12   OSHA’s range is broad and normally   adequate if local exhaust systems such   (fume hoods) are used as the primary   method of control.
        Mechanical Code   of N. Y. State   ------   Table 403.3 specifies 20 CFM per person,   based on the square footage of the area   being ventilated.
        NFPA-45-2004   Occupied “typically”   greater than 8 ACH.   Minimum 4 ACH   unoccupied.   Specifies supply diffusers have low exit   velocities and be located as far as possible   from fume hoods.
        ASHRAE Lab   Guide   4-12   This guide includes considerations for   supply air changes, exhaust air changes,   minimum outdoor air changes, and   recirculation considerations.
        Guidelines for   Design and  Construction of   Health Care   Facilities*   4-12 (depending upon   type of lab).   Table 7-1 specifies labs be negative to   adjacent areas, a supply of at least 2 ACH   of fresh outside air, and all air exhausted   directly outdoors (no recirculation of air).
        ACGIH –   Industrial   Ventilation   Depends on generation   rate & toxicity of   contaminant, not room   size.   Chapter 7:  Does not use air change rates   because ceiling heights, location of air   supply outlets, and exhausts effect the   effective air change rate.

      Some table information adapted from "Labs for the 21st Century"

      *This publication lists the “requirements” for clinical lab locations.

      As listed in the above table, ASHRAE’s Guide discusses the use of reduced air flows for unoccupied periods.  The airflow rate for unoccupied laboratories, in conjunction with NFPA, lists a minimum of 4 ACH, regardless of the type of laboratory and does not take into account state of the art ventilation controls.  Occupancy sensors, that nearly instantaneously returns the supply/exhaust ventilation to normally occupied periods, are required for locations that have reduced airflow rates for unoccupied periods.  Labs that are not in use, such as student labs and some laboratory support locations, may be set lower.

    3. Strategies to Optimize Lab Ventilation
    4. Determining the ventilation rate for a particular lab is not an exact science.  The best and most effective strategy to minimize potential exposure to chemicals starts with source control, using both containment and minimization.  Several factors help determine the minimum ventilation rate for a lab.  These factors include:

      • The types of air diffusers in a lab and the lab layout;
      • The heat load in the lab;
      • The particular process and chemicals used in a lab;
      • The local exhaust systems present in the lab; and,
      • User issues, such as the establishment and use of Standard Operating Procedures (SOPs) in the lab.

      Attempts have been made to institute Control Banding in many laboratories.  Control Banding groups substances used in an activity or a location and establishes a strategy to control possible risks.  Control Banding can be used in a lab provided the procedures and chemical hazard classes do not vary significantly during the year and only low hazard chemicals are utilized on lab benches.  Periodic review of the processes and chemicals is required to ensure the strategy is sufficient to control the risks present.

    5. Chemical Safety Levels
    6. The use of biological materials prompted the NIH and CDC to implement biological safety levels.  The American Chemical Society’s “Identifying and Evaluating Hazards in Research Laboratories, 2013”, in Table 8-1, established a similar process called Chemical Safety Levels to identify locations where higher hazard levels can be found.  Slight modifications were made to their table to accommodate the research laboratories that can be found at the UofR (listed as Chemical Safety Levels). An operational and certified chemical fume hood or other approved local exhaust ventilation is needed for the use of hazardous chemicals.

      The modified table which follows utilizes a Control Banding strategy to identify hazards in lab locations and then assigns a Chemical Safety Level to that lab.  As stated previously, the lab staff for a location must use hazardous chemicals in a chemical fume hood or utilize other approved local exhaust systems.  The lab staff must follow their Standard Operating Procedures (SOPs).  The Chemical Safety Levels range from 1 to 4, where the higher the number, the greater the potential risk.  The use of this table will better standardize ventilation rates and reduce the confusion as to what constitutes an effective ventilation rate for a laboratory.

    Table for Control Banding for Chemical Safety Levels (CSL)

    Description Of Control
      Hazard   Level   Nearly no hazards   present - Hazards   equivalent to typical   “household” locations.   Low level lab   hazards -   Teaching lab   settings (minimal   hazardous   chemicals.  Well-  established   procedures in   place).   Moderate   (variable)   laboratory hazards   - Typical labs at   University where   moderate quantities   of chemicals are   used.   High hazard   chemical labs or   processes -   Severe physical or   health hazards to   personnel
      Chemicals   Used or   Stored
    • Consumer product
    • Low hazard chemicals in use
    • Low hazard gases in use  (up to 2 cylinders like nitrogen and carbon dioxide)
    • Low conc. of acids or bases
    • Some alcohols or solvents present (less than 6 gal.)
    • Solid salts and solutions
    • Less than 4 gas cylinders (carbon dioxide, nitrogen, argon)
    • Open flames used
    • Some flammable solvents (more than 6 gallons)
    • Some corrosives (conc. acids and bases)
    • Some toxics used
    • More than 4 compressed gas cylinders
    • One tank (160 liters) cryogenics
    • Open flames
    • Lab free of air/water reactive and pyrophoric chemicals
    • More than 6 gallons of flammable solvents outside of flammable storage cabinet
    • Air/water reactive chemicals
    • Frequent use of oxidizers and corrosives
    • HF used on lab bench
    • Use of catalysts (air reactive)
    • Multiple tanks (160 liters) of cryogenics
    • Frequent use of toxic and carcinogen materials
    • Open flames
    • Frequent use of oxidizers
    • Use of chemicals considered pyrophoric or explosive
      Typical   Lab   Locations
    • Most student labs
    • Many storage rooms (not flammable storage rooms)
    • Dish washing rooms and autoclave rooms
    • Some instrumental labs (balance rooms, microscope labs, etc.)
    • Fly labs
    • Corridors
    • Some procedure rooms
    • “Dry” photo and x-ray rooms
    • Higher hazard student labs
    • Instrumental labs (using hazardous materials)
    • Some graduate student labs (not Chemistry Dept. labs)
    • “Wet” photo and x-ray development labs
    • Instrumental labs with piped or gas cylinders (no cryogenic gases)
    • Tissue culture labs
    • Specimen storage (in formalin, no cryogenic gases)
    • Large chemical storage rooms
    • Most laser labs.
    • A majority of research labs (not necessarily Chemistry Dept.)
    • Microbiological laboratories
    • Most clinical labs
    • Many specimen storage locations
    • Chemical storage rooms (little to no flammable liquids present)
    • Labs using nanomaterials
    • Animal procedure rooms
    • A majority of Dept. of Chemistry Labs
    • Flammable storage rooms
    • Many specimen storage rooms (3 or more 160 liter cryogenic tanks)
    • Gas storage rooms (manifold system present)
    • Linear equipment rooms
    • Labs manufacturing nanomaterials
    • Special cadaver use labs
    • Animal surgery room (gas anesthesia)
      ACH   occupied   Minimum 6 ACH   Minimum 8 ACH   Minimum 10 ACH   Minimum 12 ACH
      ACH non-  occupied   Minimum 2 ACH   Minimum 4 ACH   Minimum 6 ACH   Minimum 6 ACH

    Adapted from the American Chemical Society’s “Identifying and Evaluating Hazards in Research Laboratories, 2013”, Table 8-1

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This page last updated 7/30/2015. Disclaimer.