500 EM385-1-1 Construction Safety Hazard Awareness for Contractors Sections 1 - 6

06.H.03 Duration of Operation.

1. Ventilation systems must be operated continuously during operations when persons are exposed to airborne contaminants or explosive gases at or above acceptable safe limits as defined in Section 06.A.01 or as otherwise specified by this manual, referenced standards, or regulations.
2. Ventilation systems must remain in operation for a period of time after the work process or equipment has ceased to ensure the removal of any contaminants in suspension or vaporizing into the air.

06.H.04

Local exhaust ventilation systems must be periodically evaluated to ensure that proper contaminant capture, movement through the system and filtration or exhaust to the outside.

06.H.05

Dusts and refuse materials removed by exhaust systems or other methods must be disposed of in a manner that will not create a hazard to employees or the public and in accordance with Federal, State, and local requirements.

06.H.06

Ventilation systems used to remove hazardous dusts, fumes, gases, or substances must be evaluated annually to determine if the system requires cleaning. The cleaning of the ventilation system must be part of the written housekeeping program section of the Project SOH Plan or APP.

06.I Abrasive Blasting.

06.I.01 General.

Silica sand must not be used as an abrasive blasting media. Alternative abrasive blasting materials are available and listed in Table 6-3. Depending on the application, one of these alternative materials is suggested for use as an abrasive blasting media.

1. Abrasive blasting operations must be evaluated to determine composition and toxicity of the abrasive and the dust or fume generated by the blasted material, including surface coatings. This determination must be documented on the AHA (Activity Hazard Analysis) developed for the abrasive blasting activity.
2. Written operating procedures must be developed and implemented for abrasive blasting operations, including pressurized pot procedures (filling, pressurizing, depressurizing, and maintenance and inspection). The procedures should be added as an appendix to the APP.
3. The concentration of respirable dust and fume in the breathing zone of individuals exposed to the blasting operation must be maintained below any OEL for the material being blasted and the blasting agents or its byproducts.
4. No employee will be allowed to work in abrasive blasting operations unless he has met the medical surveillance and training and experience requirements, and has been provided the appropriate PPE.
5. All production and control systems used in a stationary abrasive-blasting process must be designed or maintained to prevent escape of airborne dust or aerosols in the work environment and to ensure control of the abrasive agents.
6. Pressurized systems and components must be inspected, tested, certified and maintained in accordance with the requirements of Section 20.
7. Engineering controls for noise and dust must be used even if they cannot reduce the exposures to below OEL (significantly reduces noise and dust exposure to the employees).

06.I.02 Blast Cleaning Enclosures and Rooms.

1. The ventilation in all blast enclosures must be measured annually to confirm the flow is adequate and the system does not require cleaning or maintenance. Exhaust systems must be part of a regular cleaning and maintenance program.
2. All air inlets and access openings must be baffled to prevent the escape of abrasive agent and contaminant and the recommended continuous airflow into the air inlets is a minimum of 250 fpm (4.6 kph).
3. Negative pressure must be maintained inside during blasting.
4. The rate of exhaust must be sufficient to provide prompt clearance of the dust-laden air within the enclosure after cessation of the blasting.
5. If abrasive blasting is automated, the blast must be turned off before the enclosure is opened. The exhaust system must be run for a sufficient period of time to remove the dusty air within the enclosure to minimize the escape of dust into the workroom and prevent any health hazard.
6. In the room, a cleanup method other than broom sweeping or compressed air blowing must be used to collect the abrasive agent after blasting (e.g., vacuum cleaning). If the blasting agent is removed manually, appropriate personal protective equipment, including respiratory protection must be worn and not removed until outside the blasting room.

Knowledge Check Choose the best answer for the question.