0 to 9 parts per million (ppm)
Normal - No Action: Typical from: outdoor sources, fumes from attached
garages, heavy smoking, fireplace spillage and operation of unvented combustion
appliances. With ambient conditions in this range, analysts may continue
testing sequences.
10 to 35 parts per million (ppm)
Marginal: This level could become problematic in some situations. Actions:
Occupants should be advised of a potential health hazard to small children,
elderly people and persons suffering from respiratory or heart problems.
If the home has an attached garage, document CO levels in garage. Accept
this level as normal for unvented appliances but not for vented appliances.
If unvented appliances are in operation, recommend additional ventilation
in the areas of operation. With ambient conditions in this range, analysts
may continue testing to locate the CO source.
36 to 99 parts per million (ppm)
Excessive: Medical Alert. Conditions must be mitigated. Actions: Ask occupants
to step outside and query about health symptoms. Advise occupants to seek
medical attention. If occupants exhibit any symptoms of CO poisoning,
have someone drive them to a medical facility. Enter the building, open
doors and windows to ventilate the structure. Turn off all combustion
appliances until the CO level has been reduced to safe levels. If forced
air equipment is available, continues operation of the air handler is
recommended at this time. If the home has an attached garage, document
CO levels in garage. Test combustion appliances one at a time to determine
the source of CO production. If an appliance is determined to be the source
of CO production, it should be shut off and not used until a qualified
technician with proper test equipment can service it.
100 - 200 parts per million (ppm)
Dangerous: Medical Alert. Emergency conditions exist. Actions: Evacuate
the building immediately and check occupants for health symptoms. Advise
all occupants to seek medical attention. Occupants should have someone
else drive them to a medical facility. If occupants exhibit symptoms of
CO poisoning, emergency service personnel must be called. Evacuation is
important, but Analysts must not subject themselves to excessive conditions.
Maximum exposure time is 15 minutes. Open all doors and windows that can
be done quickly. If the home has an attached garage, document CO levels
in garage. Disable combustion appliance operation. Continually monitor
indoor ambient levels while moving through the building. Once the atmosphere
within the structure has returned to safe levels and the appliances have
been turned back on, locate the source of CO production for corrective
measures.
Greater than 200 parts per million (ppm)
Dangerous: Medical Alert. Emergency conditions exist. Actions: Evacuate
the building immediately and check occupants for health symptoms. Advise
all occupants to seek medical attention. Occupants should have someone
else drive them to medical facility. If occupants exhibit symptoms of
CO poisoning, emergency service personnel must be called.
Evacuation is important, but analysts must not subject themselves to these
conditions. Do not stay inside or re-enter the building until conditions
have dropped below 100 ppm. Open all doors and windows that can be done
quickly without entering the structure. Call the local utility to shut
off gas supply (if applicable and necessary). If the home has an attached
garage, document CO levels in garage if possible to do so without being
subjected to high levels of CO. Once the atmosphere within the structure
has returned to safe levels, restore fuel supply to appliances. Operate
and test the appliances one at a time to determine the source of CO production.
What's Been Done to Control Carbon Monoxide Levels?
The Clean Air Act gives state and local governments primary responsibility
for regulating pollution from power plants, factories, and other "stationary
sources." The U.S. Environmental Protection Agency (EPA) has primary responsibility
for "mobile source" pollution control.
The EPA motor vehicle program has achieved considerable success in reducing
carbon monoxide emissions. EPA standards in the early 1970's prompted
automakers to improve basic engine design. By 1975, most new cars were
equipped with catalytic converters designed to convert carbon monoxide
to carbon dioxide. Catalysts typically reduce carbon monoxide emissions
upwards of 80 percent. In the early 1980's, automakers introduced more
sophisticated converters, plus on-board computers and oxygen sensors to
help optimize the efficiency of the catalytic converter.
Today's passenger cars are capable of emitting 90 percent less carbon
monoxide over their lifetimes than their uncontrolled counterparts of
the 1960's. As a result, ambient carbon monoxide levels have dropped,
despite large increases in the number of vehicles on the road and the
number of miles they travel. With continued increases in vehicle travel
projected, however, carbon monoxide levels will begin to climb again unless
even more effective emission controls are employed.
What Else Is Being Done?
Carbon monoxide emissions from automobiles increase dramatically in cold
weather. This is because cars need more fuel to start at cold temperatures,
and because some emission control devices (such as oxygen sensors and
catalytic converters) operate less efficiently when they are cold.
Until 1994, vehicles were tested for carbon monoxide emissions only at
75¡ F. But recognizing the effect of cold weather, the 1990 Clean Air
Act calls for 1994, and later, cars and light trucks to meet a carbon
monoxide standard at 20¡ F as well.
The 1990 Clean Air Act also stipulates expanded requirements for Inspection
and Maintenance programs. These routine emission system checks should
help identify malfunctioning vehicles that emit excessive levels of carbon
monoxide and other pollutants. The inspections will be complemented by
requirements for on-board warning devices to alert drivers when their
emission control systems are not working properly.
Another strategy to reduce carbon monoxide emissions from motor vehicles
is to add oxygen-containing compounds to gasoline. This has the effect
of "leaning out" the air-to-fuel ratio, thereby promoting complete fuel
combustion. The most common oxygen additives are alcohols or their derivatives.
Several Western U.S. cities have successfully employed wintertime oxygenated
gasolines for many years. The 1990 Clean Air Act expands this concept
and requires that oxygenated gasolines be used during the winter months
in certain metropolitan areas with high carbon monoxide levels.
For More Information:
The Office of Mobile Sources is the national center for research and policy
on air pollution from highway and off-highway motor vehicles and equipment.
You can write to us at the EPA National Vehicle and Fuel Emissions Laboratory,
2565 Plymouth Road, Ann Arbor, MI 48105. Our phone number is (734) 214-4333.
Cities* Participating in Wintertime Oxygenated Fuels Program
Albuquerque, NM
Baltimore, MD
Chico, CA
Colorado Springs, CO
Denver-Boulder, CO
El Paso, TX
Fort Collins-Loveland, CO
Fresno, CA
Grants Pass, OR
Greensboro-Winston Salem-High Point, NC
Klamath County, OR
Las Vegas, NV
Los Angeles-Anaheim-Riverside, CA
Medford, OR
Minneapolis-St-Paul, MN-WI
Missoula, MT
Modesto, CA
New York-N. New Jersey-Long Island, NY-NJ-CT
Philadelphia-Wilmington-Trenton, PA-NJ-DE-MD
Phoenix, AZ
Portland-Vancouver, OR-WA
Provo-Orem UT
Raleigh-Durham, NC
Reno, NV
Sacramento, CA
Salt Lake City, U T
San Diego, CA
San Francisco-Oakland-San Jose, CA
Seattle-Tacoma, WA
Spokane, WA
Stockton, CA
Washington, DC-MD-VA
* The 1990 Clean Air Act requires oxygenated fuels in designated CO nonattainment
areas where mobile sources are a significant source of CO emissions.
last update: 20 July 1998
The following operations may generate or involve carbon
monoxide and lead to worker exposures to this substance:
Operations near furnaces, ovens, stoves, forges, and kilns
when they are being fired up to operating temperatures; firefighting,
particularly in mines; testing of internal combustion engines; portable
stoves; manufacture and transportation of carbon monoxide.
Use in organic chemical synthesis, particularly in the Fischer-Tropsch
process for petroleum products; in fuel gas mixtures for industrial and
domestic heating; as a reducing agent in metallurgical processes such
as the Mond process for the recovery of nickel; in the manufacture of
metal carbonyl catalysts Liberation of exhaust from faulty equipment on
autos, buses, airplanes, and boats; use of compressed air in respiratory
devices in industry or breathing mixtures in diving, when the air is supplied
from reciprocating oil-lubricated compressors.
Methods that are effective in controlling worker exposures to carbon monoxide,
depending on the feasibility of implementation, are as follows:
Process enclosure
Local exhaust ventilation
General dilution ventilation
Personal protective equipment.
Response to exposure.
Workers responding to a release or potential release of a hazardous substance
must be protected as required by paragraph (q) of OSHA's Hazardous Waste
Operations and Emergency Response Standard [29 CFR
CO Inspection Protocol
Standard CO Inspection
A comprehensive protocol will be adhered to by BPI certified CO Analysts.
This protocol includes: Ambient CO Level Testing, Client Interview, Building
Inspection, Equipment Testing, Detector Utilization and Customer Education.
Standard - CO Testing, Ambient Levels
Accepted CO protocol should be followed, upon request of testing, whenever
CO contamination is suspected, and when combustion appliances are serviced.
Ambient levels will be tested before and after any work is done. All readings
will be recorded. Ambient tests must be performed prior to conducting
the client interview and/or inspections of the dwelling.
Best Practices -
Measuring Ambient CO Levels Ensure your instrument has been "warmed up"
per manufacturer instructions. Measure actual outdoor ambient CO away
from any potential source; auto, sidewall vented appliances, etc
Record outdoor reading as a baseline reference point.
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