| <<< Back to Methylene Chloride - Small Entity Compliance Guide Fact Sheets |
Printing Instructions
|
Methylene Chloride Facts No. 5
Suggested Engineering Controls and Work Practices for
Construction Sites
Occupational Safety and Health Administration (1998)
|
On January 10, 1997, the Occupational Safety and Health Administration (OSHA) issued a
standard that lowered the limit on worker exposures to methylene chloride (MC). This new
standard greatly reduces the chance of developing health problems from working in
facilities that use MC.
Worker exposures to MC occur mainly through breathing its vapors. MC can also pass
through workers' skin if it gets on their body or clothes. Occasionally, workers can
swallow small amounts of MC if they don't wash their face and hands before eating, or if
they eat in contaminated work areas. Short-term exposure to high levels of MC can cause
dizziness, headaches, a lack of coordination, and irritation of the skin, eyes, mucous
membranes, and respiratory system. Long-term exposure causes cancer in laboratory animals.
Studies in workers suggest an association between MC exposures and certain types of
cancer. OSHA considers MC to be a potential occupational carcinogen. Exposure to MC may
also make the symptoms of heart disease (e.g., chest pains, angina) worse.
About 9,505 construction companies use products that contain MC. Exposure often happens
when workers are stripping paint or other coatings, applying foam, painting with epoxy
paint, cleaning equipment with solvents, and spraying adhesives. Workers are more likely
to be exposed to high levels of MC when working in small, enclosed spaces that are not
well ventilated. The following describes some engineering controls and work practices that
you may find helpful in reducing worker exposures to MC at your site.
Monitoring
Employers must monitor worker exposures to MC to determine whether engineering controls
or work practices are necessary. Where engineering controls are already in place,
employers must monitor worker exposures to determine the effectiveness of the controls and
whether or not improvements or additional control methods are needed. Note:
Initial monitoring is not necessary if employees are exposed to MC for fewer than 30 days
per year, and the employer uses direct-reading instruments giving immediate results and
providing sufficient information to determine the necessary control measures to reduce
exposures to acceptable levels.
The revised standard published on September 22, 1998 (FR 63; 50712-50732)
contains additional STEL monitoring requirements for those specific industries taking
advantage of the extended compliance dates. For additional information on monitoring for
MC, see
OSHA
Methylene Chloride Facts No. 01 or OSHA's Chemical Sampling Information
which is accessible through
OSHA's web site.
Ventilation Systems
If monitoring results indicate that worker exposures to MC are above established limits
when working on or near a specific operation, and new or improved controls are necessary,
consider using one or more of the following ventilation control options:
- Where possible, use MC products outdoors.
- Use a portable local exhaust ventilation (LEV) unit when working with MC indoors or in
areas with limited ventilation for long periods of time.
- Be sure to use a replacement air system, or else the LEV will not work properly.
- Turn on portable LEV units several minutes before you enter the work area.
- Run the LEV at a high enough airflow to reduce exposures below the 8-hour time-weighted
average (TWA) permissible exposure limit (PEL), and 15-minute short-term exposure limit
(STEL).
After you install a new ventilation system, you must monitor worker exposures again to
determine whether the system is effective. Note: Check with the
appropriate local, county, or state environmental office to make sure you have the
required permits if you will be exhausting MC directly outside.
General (or dilution) ventilation uses fans or open windows to move clean air through
the work area. This does not confine MC vapors to one area, so it does not protect workers
as well as LEV. General ventilation can sometimes reduce MC to acceptable levels in areas
where exposures are not very high.
- Turn on general ventilation at least an hour before work begins or leave it on
overnight.
Keep MC Vapors Contained
- Store and transport MC products only in approved safety containers.
- Properly label all MC product containers to indicate their contents, hazards, and proper
use, storage, and disposal. Read these labels and follow the directions.
- Keep MC product containers closed tightly when not in use.
- Avoid unnecessary transfer or movement of MC products.
Avoid Breathing MC Vapors
- Avoid breathing the air directly above areas covered with MC. Do not lean over an area
covered with MC.
- Do not work or stand between MC-covered areas and the exhaust system.
- Do not rely on the odor of MC to warn you of over-exposure. People cannot smell MC until
vapor concentrations are above 300 ppm, which is 12 times higher than the 8-hour TWA PEL
of 25 ppm. Also, your sense of smell can quickly get used to the odor of MC so that you
stop noticing it.
- If you become dizzy, light-headed, or have other symptoms of MC exposure, go immediately
to an area with fresh air.
Avoid Direct Skin Contact with MC
- Wear two pairs of gloves when using stripping solution. The inner glove should be made
of polyethylene (PE)/ethylene vinyl alcohol (EVOH), PE, or laminate to prevent MC
penetration. The outer glove should be made of nitrile or neoprene to protect against
puncture or rips. [Note: Because MC can readily penetrate nitrile and neoprene, wearing
just the outer glove will not protect your skin from MC exposure.]
- Wear shoulder length gloves, or the longest gloves possible.
- Before use, inspect gloves for pin-holes, cracks, thin spots, softening, swelling, and
stiff or sticky surfaces.
- Change gloves frequently, before breakthrough occurs.
- Rotate several pairs of gloves throughout the day.
- Let gloves dry in a warm, well-ventilated area at least overnight before reuse.
- Wear rubber aprons and boots or shoe covers to prevent MC from getting on your clothes,
which results in prolonged skin contact with MC.
- Wear a face shield or goggles to protect your face and eyes.
- Use the washing facilities in your work area to wash off any MC from your hands and
face.
- Use lots of soap or mild detergent and water to clean grease, oil, dirt, or anything
else off your skin. Do not use MC or other organic solvents to clean your skin.
Minimize the Chance of Spills and Leaks
- Develop and follow procedures for containing MC spills or leaks.
- Frequently inspect MC product containers for cracks or other possible sources of leaks.
- Clean up all spills and leaks as quickly as possible.
- Place rags, waste, paper towels, or absorbent used to clean spills in a closed container
(preferably a non-aluminum, all-metal safety container) immediately after use.
- Make sure that leaks are repaired and spills cleaned up by employees who are trained in
proper cleanup methods. These employees should wear appropriate personal protective
equipment (PPE).
Take Extra Precautions in Low and Confined Spaces
MC vapors are heavier than air, so they tend to move to low, unventilated spaces.
- Do not enter or lean into a low-lying confined area until it has been completely aired
out and tested. Wear proper PPE and follow the appropriate confined space entry procedures
outlined in OSHA's Permit Required Confined Spaces standard (
29 CFR 1910.146).
- Use a long-handled tool to pick up items that you drop in areas where MC is being used.
Take Personal Precautions
- After working with MC, always wash your face and hands before eating.
- Never eat in the work area or your food and drink could become contaminated with MC.
- Avoid drinking alcohol before or after being exposed to MC. Alcohol can lower the amount
of MC needed to cause health problems.
- Be alert when working with MC. Avoid situations that might result in overexposure.
- If your clothes become soaked with MC, remove them and take a shower. Do not put your
clothes back on until they are thoroughly clean and dry.
Substitutes
Using products that do not contain MC is a good way to reduce worker exposure to MC.
Many adhesives, solvents, foams, and paints no longer use MC as a propellant and are
widely available (check labels). In addition, a number of paint strippers that do not
contain MC are currently available.
- n-Methyl-pyrrolidone (NMP) can remove clear and pigmented nitrocellulose lacquers,
conventional varnish, and all types of water-based coatings as well as MC.
- Methanol, acetone, and toluene can remove many finishes and paints. These substitutes
are extremely flammable, so be sure to take appropriate precautions.
Keep in mind that substitutes may also present health and safety hazards to workers.
Always select substitutes that reduce hazards, and always refer to the substitute's
material safety data sheet to find out about any control measures and protective equipment
you must use to protect workers.
Respirators
If engineering controls and work practices do not reduce MC exposures to an acceptable
level, workers must wear supplied-air respirators. Respirators are the least preferred
method of controlling employee exposure. Supplied-air respirators must have a clean air
supply through the use of compressed air tanks containing air meeting at least the
requirements for Grade D breathing air, or a breathing air type compressor with the air
intake located in an area with a clean air supply. CAUTION: Filter
cartridge respirators cannot be used because MC can pass through available cartridges
leaving respirator wearers unprotected.
Compliance Schedule
Employers with 1 to 19 employees (in the selected application group) have until:
- February 4, 1998 to implement paragraph (d) (Initial Monitoring).
- April 10, 2000 to implement paragraph (i) (Engineering Controls).
- April 10, 2000 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- April 10, 1998 to implement all other provisions.
Employers with 1 to 19 employees (not in the selected application group) have until:
- February 4, 1998 to implement paragraph (d) (Initial Monitoring).
- April 10, 2000 to implement paragraph (i) (Engineering Controls).
- April 10, 1998 to implement all other provisions.
Employers with 20 to 49 employees (in the selected application group) have until:
- September 7, 1997 to implement paragraph (d) (Initial Monitoring).
- April 10, 2000 to implement paragraph (f) (Engineering Controls).
- April 10, 2000 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- December 21, 1997 to implement all other provisions.
Employers with 50 or more employees (in the selected application group) have until:
- September 7, 1997 to implement paragraph (d) (Initial Monitoring).
- April 10, 1999 to implement paragraph (f) (Engineering Controls).
- April 10, 1999 to implement Respiratory Protection to achieve the 8-hour TWA PEL only.
- December 21, 1997 to implement all other provisions
Employers with 20 or more employees (not in the selected application group) have until:
- September 7, 1997 to implement paragraph (d) (Initial Monitoring).
- April 10, 1998 to implement paragraph (f) (Engineering Controls).
- December 21, 1997 to implement all other provisions.
* Selected application group are those who use MC in construction work
for restoration and preservation of buildings, painting and paint removal, cabinet making,
or floor refinishing and resurfacing.
Additional Resources
For more information concerning consultation assistance, contact the
nearest OSHA office (look under state listings for the Department of Labor),
refer to the listings on
OSHA's web site,
or contact OSHA's Office of Information at (202) 219-8151.
|
| |
|
