510 EM 385-1-1 Chapters 1-8

Sections

6-8. General Requirements.

Ventilation and Exhaust Systems

Portable and temporary ventilation systems must remove harmful substances and provide clean air to prevent oxygen-deficient environments.
Operate and maintain ventilation systems to keep exhaust air volume and velocity high enough to safely remove contaminants.
Continuously operate ventilation during work with contaminants above safe limits and ensure systems are evaluated regularly.

Abrasive Blasting

Develop an Abrasive Blasting Plan and train employees on it. Do not use silica sand as a blasting media.
Maintain negative pressure in blast cleaning enclosures and ensure exhaust systems run after blasting to clear dust-laden air.
Use appropriate respiratory and hearing protection when blasting without enclosures and follow guidelines for confined spaces and outdoor blasting.

Personal Protective Equipment (PPE)

Select and use PPE according to guidelines, ensuring it's cleaned and not taken home for laundering.
Issue individual PPE items to each employee and maintain air-supplied respiratory equipment properly.
Perform daily checks on PPE, ensuring it's in good condition and replace damaged parts like safety glasses and faceplates in helmets.

Thermal Stressors Management

Develop a Thermal Stress Management Plan, monitoring environmental conditions and adjusting workload accordingly.
Provide potable drinking water, allow acclimatization to work conditions, and monitor weather to schedule work minimizing thermal stress.
Follow thermal stressor management recommendations from authoritative sources like CDC/NIOSH, OSHA, and Defense Centers for Public Health.

Knowledge Check Choose the best answer for the question.

6-10. Portable and temporary ventilation systems must remove harmful substances and provide clean air _____.

to prevent oxygen-deficient environments

and reduce carbon dioxide levels

at enriched levels

to comply with building codes

You forgot to answer the question!

EM 385-1-1 Paragraph 6-8 (j.–m.).

6-8. General Requirements (j.–m.).

j.  Ventilation and Exhaust Systems.  (6-8.j)

(1)  Portable and Temporary Ventilation Systems.

(a)  All portable or temporary ventilation systems must remove dusts, fumes,
    mists, vapors, and gases away from the worker and the work environment or provide air to prevent an oxygen deficient atmosphere.

(b)  Portable or temporary ventilation systems must be used as designed by the manufacturer. All hoses must be only as long as the maximum allowed by the manufacturer to provide the required air flow at the supply or exhaust point.  If adding or
        changing hoses, use only hoses and/or connectors that are comparable and compatible with the hoses and connectors provided by the manufacturer.

(c)  Make-up air for air supply ventilation systems must draw air free of contaminants and away from any potential contaminant source.

(d)  Any portable or temporary ventilation system and the locations where the systems are to be used must be approved by the local SOHO/USACE supervisor or accepted by the KO or COR before use.  Provide manufacturer information or design criteria with the request for acceptance.

(e)  Use high efficiency, filtered, recirculated ventilation units when:

(e-1)  The filtration system lowers the levels of any airborne contaminants from the operation to less than half of the OEL.  This must be documented by an IH or CP through sampling for the contaminants.

(e-2)  The unit and filtration are regularly maintained and the maintenance procedure and schedule are written and documented when maintenance is completed.

(2)  Ventilation systems must be operated and maintained to ensure the maintenance of volume and velocity of exhaust air is sufficient to gather contaminants and safely transport them to suitable points for removal.

(3)  Duration of Operation.

(a)  Ventilation systems must be operated continuously during operations when persons are exposed to airborne contaminants at or above the OEL or explosive gases at or above acceptable safe limits as defined in paragraph 6-8.b or as otherwise specified by this manual, referenced standards, or regulations.

(b)  Ventilation systems must remain in operation for a time after the work process or equipment has ceased to ensure the removal of any contaminants in suspension or vaporizing into the air.

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

(5)  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 according to this manual, applicable federal, state, and local requirements.

(6)  Evaluate ventilation systems used to remove hazardous dusts, fumes, gases, or substances according to paragraph 6-5.c.  The cleaning of the ventilation system must be part of the written Housekeeping Plan.  (See chapter 35)

k.  Abrasive Blasting. Silica sand must not be used as an abrasive blasting media. Alternative abrasive blasting materials are available and listed in table 6-1.  (6-8.k)

(1)  When abrasive blasting is performed, an Abrasive Blasting Plan must be developed and employees trained according to paragraphs 6-7.f and 6-3.h.

(2)  Blast Cleaning Enclosures and Rooms.

(a)  Exhaust systems must be part of a regular cleaning and maintenance program (see para 6-5.d).

(b)  All air inlets and access openings must be baffled to prevent the escape of abrasive agents and contaminants.

(d)  Negative pressure must be maintained inside during blasting.

(e)  Transport velocities of the system must be at a minimum 3,500 feet per minute (fpm) (17.8 m/s), but 4,000 to 5,000 fpm (20.3 to 25.4 m/s) is recommended by ANSI Z9.4.

(f)  The rate of exhaust must be sufficient to provide prompt clearance of the dust- laden air within the enclosure after cessation of the blasting.  Appendix A of ANSI Z9.4 outlines minimal airflow velocities for various devices.

(g)  If abrasive blasting is automated, the blast must be turned off before the enclosure is opened. The exhaust system must run for a sufficient period to remove the dusty air within the enclosure to minimize the escape of dust into the workroom and prevent any health hazard.

(h)  Perform routine cleanup using wet methods or HEPA filtered vacuuming to minimize the accumulation of dusts.  Broom sweeping or compressed air is prohibited. If the blasting agent is removed manually, appropriate PPE, including respiratory protection, must be worn and not removed until outside the blasting room.

(i)  For blasting cabinets, inward air velocity at the hand openings must be 500 fpm (2.5 m/s) measured at the free openings without the curtains due to proximity of operator.  Gloves inserted must be inspected prior to every use according to paragraph
        6-5.d. The cabinet must have a minimum of 20 air changes per minute.

(3)  Blasting Without Enclosures.

(a)  If abrasive blasting must be performed inside a building without enclosures, respiratory protection must be provided for all employees in the area according to
        chapter 5. Portable engineering control devices must also be used at the location to collect the entire used abrasive agent as it is applied.

(b)  When airborne abrasive blasting dust becomes sufficiently heavy in an area to cause a temporary safety hazard by reduced visibility or discomfort to the unprotected employees not engaged in abrasive blasting, such operations in the affected area must be discontinued until the airborne dust is removed by exhaust ventilation and the settled dust has been removed from the horizontal surfaces in the area.

(d)  If wet abrasive blasting is employed to reduce dust exposures, the aerosols produced and the dried residues that become airborne might be potential hazards and must be considered.

(4)  Confined Spaces.  Abrasive blasting work conducted in a confined space must be performed according to chapter 34.   Use exhaust ventilation systems in containment structures to capture dust.

(5)  Blasting Outdoors.

(a)  Work completed outside has been shown to create exposures to health hazards for the worker and other trades in the area.  Air and noise samples must be taken to document the level of exposure to the worker and the workers in the area, unless similar operations documented no exposure.  Blasters must be protected with proper PPE (see chapter 5) and proper ventilation (see 29 CFR 1910.94).

(b)  Engineering controls and work practices, such as wet blasting methods, must be used to prevent the dust from spreading to other work areas.  Check with local and state requirements which may add restrictions to outdoor abrasive blasting.  If the surface to be blasted is painted or contains high levels of silica and/or heavy metals, such as lead, chromium, or cadmium, an enclosure may be required to prevent disbursement of the hazard.

(6)  Hearing protection and respiratory protection must be available to all employees in areas where the associated hazards exist (see chapter 5).

l.  Personal Protective Equipment (PPE).  (6-8.l)

(1)  Select and use PPE according to chapter 5.  If reusable coveralls are used, they must be vacuumed before all breaks and removed at the end of the shift.  Clothes must not be taken home to be cleaned by the worker or family, they must be laundered by the employer.  (See chapter 35)

(2)  Air-supplied helmets, blast helmets/hoods, respirators, earmuffs, safety boots or toe guards, durable coveralls closeable at wrists, ankles, and other openings, and safety glasses should be an individual issue item, identified with and used by only one employee.  Such equipment may be reissued to another employee only after complete cleaning, repair, and decontamination.

(3)  Clean and store air-supplied respiratory equipment after each shift of use. Storage must be in a clean enclosure such as locker, footlocker, plastic container, or zip-lock type bag.  Employees must be trained to maintain issued equipment in clean and good working condition.

(4)  Replace visibly damaged safety glasses (plano or prescription).

(5)  Replace faceplates in air-supplied helmets and blast helmets/hoods when a side-on light source produces obscuring visible reflections and glare from the etched spots and pit holes in the faceplate.  Mylar coating, or similar transparent plastic material, is recommended to protect the glass or plastic faceplate.

(6)  Do not alter the length of air hose(s) from the manufacturer's specifications.

(7)  Daily checks must be performed by the wearer of PPE to maintain it in good
    working condition. Rips, tears, and openings of PPE that expose skin to abrasive agents must be mended or replaced.  Functional tests for leaks, proper respiration, and good connections must be performed on the complete air-supply system.

(8)  Air supply, portable.

(a)  The breathable air supplied to the blast helmet or hood must be Grade D quality air per 29 CFR 1910.134(i) for breathing air quality and use.  The compressed air used for blasting must be isolated and separated from the compressed air line used for breathing air.  The compressed air line for breathing air must be used per
        manufacturer’s recommendations and be adequately labeled to clearly state quality air if being provided by the same compressor as the blasting air.  Breathable air-supply system should be equipped, if possible, with audible alarm at the helmet or hood to
        warn the user of low air pressure.

(b)  Hearing protection.  Suitable hearing protection, capable of attenuating employee noise exposure according to chapter 5, must be worn.

(c)  Heat stress. Cooling of breathable air, supplied to the blast helmets/hoods, should be considered depending on season and employee exposure to heat sources.

m.  Thermal Stressors Management. When employees may be exposed to thermal stressors, a Thermal Stress Management Plan must be developed and employees trained according to paragraphs 6-7.g and 6-3.c.  Take into consideration the influence of environmental conditions, workload, and personal factors.  (6-8.m)

(1)  Implement a buddy system. Workers should not only monitor themselves, but also be alert to changes and the symptoms of their co-workers.

(2)  Provide readily available potable drinking water to all employees (see chapter 35).

(3)  Allow workers to adequately acclimatize to work conditions.

(4)  Monitor weather conditions.  When possible, schedule work activities to minimize thermal stress exposure.

(5)  Comply with thermal stressor management recommendations as promulgated by Centers for Disease Control (CDC)/NIOSH Heat Stress and Cold Stress (see https://www.cdc.gov/niosh/topics/heatstress/default.html or https://www.osha.gov/winter-weather/cold-stress), OSHA Heat Stress and Cold Stress (see https://www.osha.gov/heat-exposure or https://www.osha.gov/winter-weather/cold- stress), and the Defense Centers for Public Health - Aberdeen Heat Illness Prevention and Cold Injury Prevention (see https://phc.amedd.army.mil/topics/discond/hipss/Pages/default.aspx or https://phc.amedd.army.mil/TOPICS/DISCOND/CIP/Pages/default.aspx).

510 EM 385-1-1 Chapters 1 - 8