10.1 Purpose. To ensure that employees are protected from harmful airborne substances in the work environment.

10.2 Scope. This program applies to all indoor operations where there is a potential for release of aerosols or vapors containing hazardous or pathogenic substances, or excessive amounts of nontoxic dusts or fumes. Control of similar emissions from outdoor operations will depend on natural air movements or use of respiratory protective equipment by the Service employees involved. General ventilation systems used to promote occupant comfort and suppress odors in offices, auditoriums, and normal work areas are not covered by this program.

10.3 Policy. The Service policy is to comply with all pertinent guidelines for ventilation systems used to control releases of hazardous aerosols or vapors into workplaces. The requirements set forth in the Industrial Ventilation Manual of the American Conference of Governmental Industrial Hygienists (ACGIH) and those of the National Fire Protection Association (NFPA) will be followed. Biological safety cabinets used in Service operations will conform to the criteria recommended by the National Institutes of Health. The program used for each specific operation will include the following three elements:

A. Selection of correct ventilation system.

B. Rules for proper use of ventilation system.

C. Maintenance and inspection.

10.4 Objectives. The Service objective is to prevent airborne diffusion of hazardous and pathogenic substances in the work environment through capture at the point of origin.

10.5 Authority.

A. Occupational Safety and Health Act (OSHA) 1970 - Public Law

91-596, Section 19 - Federal Agency Safety and Health Program.

B. Executive Order 12196, Occupational Safety and Health Programs for Federal Employees.

C. 29 CFR 1960 - Basic Program Elements for Federal Employees, Occupational Safety and Health Programs.

D. 5 U.S.C. 7901, 7902, 7903.

E. 485 DM.

10.6 Definitions.

A. Capture Velocity. Minimum air velocity needed to draw contaminants into an enclosure or hood.

B. Differential Pressure. Difference in static pressure between two areas.

C. Duct. A conduit used for conveying air at low pressure.

D. Dust. Small solid particles released by breaking up or grinding of larger solid material.

E. Fume. Small solid particles formed by reaction or condensation of materials in vapor form.

F. Hood. Inlet of an exhaust ventilation system. Hoods are classified into four groups:

(1) Canopy Hood. A type located over the source of emission to be controlled.

(2) Capturing Hood. A type with sufficient airflow (i.e., face velocity) to draw in contaminants released inside or close to open face of hood.

(3) Enclosing Hood. A type that encloses the contaminant source, such as a laboratory hood.

(4) Slotted Hood. A type consisting of one or more narrow slots leading into a plenum chamber so as to obtain an even distribution of air velocity along the slotted face.

G. Hood Static Pressure. The negative pressure existing in the exhausting duct immediately at the connecting point with attached hood, which indicates the amount of suction available to draw air into the hood.

H. Static Pressure. Potential pressure exerted in all directions by a fluid at rest.

10.7 Responsibilities. These responsibilities supplement those contained in 240 FW 1.5.

A. Project Leader has the responsibility to:

(1) Ensure proper design of all project ventilation systems. This requires that an appropriate qualified engineer be advised of the intended use of the system, including the specific hazardous substances to be controlled. Any modification of design will require additional engineering review to ensure effective operation. (See 242 FW 10.8B(3).)

(2) Ensure that project ventilation systems are inspected in accordance with 242 FW 10.8C and that the latest inspection results are posted adjacent to minimum acceptable performance standards.

(3) Obtain assistance in accordance with 242 FW 1 when appropriate.

(4) Ensure compliance with all provisions of this chapter.

10.8 Program. Ventilation systems must be provided for work areas where the atmosphere can be contaminated by toxic, irritating, or other harmful materials. Similarly, adequate ventilation must be provided whenever hazardous substances, particularly flammable ones, are released in amounts which can create a fire or explosion risk. The system selected shall be appropriate to the degree of environmental control that is required by relevant codes and guidelines.

The design process will include review of all hazards to be controlled, as well as the type of ventilation control required. Minimum acceptable performance standards or specifications will be visibly posted on all hoods. A listing of acceptable uses of the ventilation system will be maintained in the immediate work area.

A. Selection of Correct Ventilation Systems.

(1) The design process will include a review of all hazards to be controlled by appropriate ventilation. Rate of contaminant emission and nature of the emission such as dust, smoke, gas, or vapor will be noted. The area to be controlled will be defined, as well as the eventual need to provide for air cleaning before release into the environment.

(2) The principles offered in the current Industrial Ventilation Manual of the American Conference of Governmental Industrial Hygienists will be used in selecting ventilation systems. Off-the-shelf fume hoods will be preferred to custom-designed ones, if available.

B. Use of Ventilation Systems.

(1) Any ventilation system installed to control diffusion of specific hazardous materials will be used primarily for that purpose. It will not be used for other hazardous substances before verification that it is able to offer the required control. If the controlled materials are corrosive, it will also be verified that the ventilation system has been designed and built in a fashion which makes it corrosion proof.

(2) A list of acceptable uses of each ventilation system will be maintained in the general work area. The list will contain the authorizing signature of the project leader. Only specified uses in the listing are authorized.

(3) Modification of operations or new operations will require additional review, unless provided for in the listing of acceptable uses.

C. Maintenance and Inspection.

(1) The protection offered by ventilation systems depends greatly on their level of performance. As this can be affected by wear and tear, it is important to verify that the system does perform as required. New installations will be tested thoroughly to make sure that their operation conforms to specifications. Installing differential pressure indicators to monitor the hood static pressure will be considered for existing and new installations.

(2) Existing ventilation systems will be inspected routinely and their performance evaluated in relation to the controls needed for the operations conducted. Airflow across any hood face shall be at least equal to the capture velocity recommended for the emission controlled. For laboratory hoods in daily use, this inspection will be conducted at least every 6 months. For other systems which are not used frequently, performance will be verified at least yearly.

(3) Inspection of ventilation systems will measure the airflow to verify conformance with applicable guidelines for the particular operation controlled. If the area to be controlled exceeds 0.4645 square meters, (5 square feet), a sufficient number of measurements will be taken to assess the air volume flowing across the hood face. With the use of smoke tubes or similar air current detectors, the air pattern will be evaluated and any irregularity detected. Leakage around the ventilation system will also be searched for with smoke tubes.

(4) If preliminary inspection indicates that performance is not at an acceptable level, a detailed review of the ventilation system will be conducted. This will include the following critical elements:

(a) Speed of fan and fan blades.

(b) Belt conditions or tension.

(c) Duct cleanliness and good repair.

(d) Filters and flow control devices.

(e) Cracks and other defects.

(5) Routine maintenance will be conducted as required, including greasing of bearings or filter changes.

(6) Each station will maintain records of inspection for a minimum of 4 years. This requirement will not negate the requirement for posting of inspection results adjacent to minimum acceptable performance standards on all hoods. (See 242 FW 10.7A(2).)