THE ADVERSE HEALTH
EFFECTS OF Diesel Exhaust/Diesel Particulate Matter
Diesel engines provide power to a wide variety of
vehicles, heavy equipment, and other machinery used in a large number of
industries including mining, transportation, construction, agriculture,
maritime, and many types of manufacturing operations. The exhaust from diesel
engines contains a mixture of gases and very small particles that can create a
health hazard when not properly controlled.
Diesel-powered
equipment is often used in underground mines.
Photo courtesy of MSHA
What
is Diesel Particulate Matter (DPM)?
·
DPM
is a component of diesel exhaust (DE) that includes soot particles made up
primarily of carbon, ash, metallic abrasion particles, sulfates and silicates.
·
Diesel
soot particles have a solid core consisting of elemental carbon, with other
substances attached to the surface, including organic carbon compounds known as
aromatic hydrocarbons.
Who
can be exposed to DE/DPM?
Occupations
with potential exposure to DE/DPM include miners, construction workers, heavy
equipment operators, bridge and tunnel workers, railroad workers, oil and gas
workers, loading dock workers, truck drivers, material handling operators,
farmworkers, long-shoring workers, and auto, truck and bus maintenance garage
workers.
Most
heavy-and medium-duty trucks are equipped with diesel engines, as well as
equipment used in mines; buses, locomotives and ships; heavy equipment such as
bulldozers and tractors; and other types of equipment such as bucket lifts and
generators. Miners and other workers in the vicinity of diesel powered
equipment may be exposed to DE/DPM.
What
are the health effects of DE/DPM?
·
Short
term exposure to high concentrations of DE/DPM can cause headache, dizziness,
and irritation of the eye, nose and throat severe enough to distract or disable
miners and other workers.
·
Prolonged
DE/DPM exposure can increase the risk of cardiovascular, cardiopulmonary and
respiratory disease and lung cancer.
In
June, 2012, the International Agency for Cancer Research (IARC) classified DE
(including DPM) as a known human carcinogen (Group 1).
Heavy
equipment operators can be exposed to diesel exhaust at construction sites. Photo courtesy of NESCAUM
How
can exposures to DE/DPM be controlled?
Engineering
controls are the most effective strategy for minimizing worker exposure to
DE/DPM. A combination of controls is often required. Examples include:
·
Performing
routine preventive maintenance of diesel engines to minimize emissions,
·
Installing
engine exhaust filters,
·
Installing
cleaner burning engines,
·
Installing
diesel oxidation catalysts,
·
Using
special fuels or fuel additives (e.g., biodiesel),
·
Providing
equipment cabs with filtered air, and
·
Installing
or upgrading main or auxiliary ventilation systems, such as tailpipe or stack
exhaust vents to capture and remove emissions in maintenance shops or other
indoor locations.
Administrative
controls refer to changes in the way work tasks are performed to reduce or
eliminate the hazard. Examples include:
·
Limiting
speeds and using one-way travel routes to minimize traffic congestion,
·
Prohibiting
and/or restricting unnecessary idling or lugging of engines,
·
Restricting
the amount of diesel-powered equipment and total engine horsepower operating in
a given area and ensure that the number of vehicles operating in an area does
not exceed the capacity of the ventilation system, and
·
Designate
areas that are off-limits for diesel engine operation and/or personnel travel.
What
standards are in place to protect miners and other workers from exposures to
DE/DPM?
Miners
are covered by the Mine Safety and Health Administration (MSHA). Workers in
general industry, agriculture, construction and maritime industries are covered
by the Occupational Safety and Health Administration (OSHA).
MSHA
currently enforces DPM standards at underground metal/nonmetal mines and at
underground coal mines.
Underground
Metal/Nonmetal Mines
·
A
miner's personal exposure to DPM must not exceed 160 micrograms per cubic meter
(μg/m3) of total carbon (TC) when measured as an 8-hour
time-weighted average.
·
Feasible
engineering and administrative controls are required to reduce a miner's
exposure to or below the permissible exposure limit (PEL).
·
Respiratory
protection must be used to supplement feasible engineering and administrative
controls if such controls do not reduce a miner's exposure to the PEL, the
engineering or administrative controls are infeasible, or the engineering and
administrative controls fail to produce a significant reduction in DPM
exposure.
·
When
respiratory protection is required, an air-purifying respirator equipped with a
filter that meets one of the following: certified by NIOSH under 30 CFR Part 11
as a high-efficiency particulate air (HEPA) filter; under 42 CFR Part 84 as
99.97% efficient; or certified by NIOSH for DPM.
·
Rotation
of miners to comply with the PEL is prohibited.
·
Evaluation
of a miner's medical ability to wear a respirator and transfer rights for
miners unable to wear respirators.
·
Other
requirements include:
o
Fueling
practices, including sulfur content and fuel additives,
o
Maintenance
of diesel-powered equipment,
o
Limits
on engine emissions,
o
Annual
training for miners,
o
Exposure
monitoring,
o
Recordkeeping,
and
o
Miners'
and former miners' rights to access certain records related to their own
exposures.
Underground
Coal Mines
·
DPM
emissions of diesel-powered equipment are restricted to the levels indicated
below based on laboratory tests on the engine exhaust:
o
Permissible
Equipment - 2.5 grams/hour
o
Heavy-Duty
nonpermissible - 2.5 grams/hour
o
Light
Duty nonpermissible - 5.0 grams/hour or EPA standards
·
MSHA
laboratory testing establishes the level of DPM filtration required on specific
diesel engines.
·
Coal
mine operators are required to:
o
Perform
weekly examinations of diesel equipment and perform maintenance with certified
mechanics,
o
Use
low sulfur fuel,
o
Provide
training to miners annually on DPM risks and controls used at the specific
mine,
o
Maintain
exhaust gas concentrations at or below established standards, and
o
Provide
ventilating air where diesel engines are operated.
General
Industry, Agriculture, Construction and Maritime Operations
|
Substance
|
PEL
|
|
Carbon
Monoxide (CO)
|
50
ppm
|
|
Nitric
Oxide (NO)
|
25
ppm
|
|
Nitrogen
Dioxide (NO2)
|
5
ppm (ceiling)
|
The
Occupational Safety and Health Administration does not have a a permissible
exposure limit (PEL) for DPM. However, OSHA has PELs for other components of
diesel exhaust. Monitoring for these gases can provide an indication of the
presence of DE, and can be of help in evaluating the effectiveness of
engineering and administrative controls implemented to minimize the potential
for exposure to DE when working with or around diesel-powered equipment.
Where
can I get additional information?
The
links below can be used to access additional information regarding diesel
regulations and technical information on control measures.
The
EPA recommends strategies for reducing diesel exhaust on their website.
Contacts
MSHA:
For
questions, information or advice:
·
Metal/Nonmetal
Mine Safety and Health, Division of Health, Reginald J. Richards, DrPH, CIH,
(202) 693-9632, richards.reginald.j@dol.gov
·
Coal
Mine Safety and Health, Division of Health, Robert A. Thaxton, (202) 693-9515, thaxton.robert@dol.gov
To
report an emergency, fatality or catastrophe, or to file a confidential hazard
complaint, contact your nearest MSHA district or field office, visit www.msha.gov, or call MSHA at
1-800-746-1553.
OSHA:
For
questions, information or advice, to report an emergency, fatality or
catastrophe, or to file a confidential complaint, contact your nearest OSHA
office, visit www.osha.gov, or call at
1-800-321-OSHA (6472).
