Carbon Monoxide Concentrations: Table (AEN-172)

ISU Extension Pub # AEN-172
Author: Thomas H. Greiner, Extension Agricultural Engineer
Department of Agricultural and Biosystems Engineering, Iowa State University.
August, 1997

CARBON MONOXIDE POISONING
Carbon Monoxide Concentrations: Table

Concentration of CO in Air Effects, Inhalation Time and Toxic Symptoms Developed

1-2 ppm

Might be normal, from cooking stoves, spillage, outdoor traffic

>2 ppm

Raises questions about why CO is elevated. Source should be identified, might be normal (ie, traffic, kitchen range) (Energy Conservatory).

9 ppm

The maximum allowable concentration for 8-hour period in any year, EPA (ASHRAE). Polluted cities often reach and exceed 9 ppm, increasing incidence of congestive heart failure (Morris). Typical concentration after operation of unvented gas kitchen range (Tsongas).

15 ppm

U-L standards for residential detectors require that they NOT alarm at 15 ppm unless exposure is continuous for 30 days. (U-L concentration being raised).

15-20 ppm

Impaired performance in time discrimination (HbCO 2.0)
Decrease in absolute exercise time (HbCO 2.5)
Shortened time to angina response (HBCO 2.9)
Vigilance decrement (HbCO 3.0) (World Health Org. 13).

20 ppm

Typical concentration in flue gases (chimney) of a properly operating furnace or water heater. (Greiner, unpublished)

27 ppm

21 percent increase in cardiorespiratory complaints (Kurt, 1978

30 ppm

Earlier onset of exercise-induced angina (HbCO 4.96%) (WHO 13

35 ppm

Maximum allowable outdoor concentration for one-hour period in any year, EPA (ASHRAE)

40 ppm

Some residential detectors might give a low-level alarm after several hours exposure. (Not verified).

50 ppm

Maximum allowable 8-hours work place exposure, (OSHA). Most fire departments require use of self-contained breathing apparatus for exposures above 50 ppm. Preziosi et.al found chronic exposures produced significant morphologic changes in dogs, including brain pathology, heart pathology and abnormal EKG’s. Other researchers find higher concentrations needed. Minimum concentration for digital display to move from zero on some detectors with displays (Conversation with manufacturer).

75 ppm

Significant decrease in oxygen reserve available to the myocardium (HbCO 10%). Heavy smokers can reach HbCO of 10%.

80 ppm

Many residential detectors might alarm after several hours exposure. Level and time to alarm varies with manufacturer. (Not verified).

100 ppm

U-L listed detectors must sound a full alarm within 90 minutes or less. Most alarm more quickly. Time to alarm varies with manufacturer, with some manufacturers electing to sound the alarm more quickly. Slight headache, tiredness, dizziness, nausea after several hours exposure. Causes morphologic damage to hearts and brains in dogs exposed 5 1/2 hours per day for eleven weeks (Lewey and Drabkin, quoted in Preziosi). Maximum concentration allowed from kitchen range ovens by many weatherization agencies (Tsongas).

110 ppm

Concentration in indoor ice skating arena (Kwok)

200 ppm

Maximum recommended workplace exposure (NIOSH). U-L listed detectors must sound a full alarm within 35 minutes. Time to alarm varies with manufacturer, with some manufacturers electing to sound the alarm more quickly. Slight headache, tiredness, dizziness, nausea after 2-3 hours, might be life-threatening in long exposures (Bacharach). Abortions and lower birth rates in pigs (Carson).

400 ppm

U-L listed detectors must sound a full alarm within 15 minutes. Time to alarm varies with manufacturer, with some manufacturers electing to sound the alarm more quickly. Frontal headaches within 1-2 hours, life-threatening after 3 hours, maximum parts per million in flue gas under AGA test guidelines.

500 ppm

Often produced in garage when a cold car is started in an open garage and warmed-up for 2 minutes. (Greiner, unpublished, 1997).

800 ppm

Dizziness, nausea and convulsions within 45 minutes. Unconsciousness within 2 hours. Death within 2-3 hours. Maximum air-free concentration from gas kitchen ranges (ANSI).

1600 ppm

Headache, dizziness and nausea within 20 minutes. Death within 1 hour. Smoldering wood fires, malfunctioning furnaces, water heaters, and kitchen ranges typically produce concentrations exceeding 1,600 ppm.

3200 ppm

Concentration inside charcoal grill (Greiner, single example). Headache, dizziness and nausea within 5-20 minutes. Quickly impaired thinking. Death within 30 minutes.

6400 ppm

Headache, dizziness and nausea within 1-2 minutes. Thinking impaired before response possible. Death within 10-15 minutes.

12,800 ppm

Death within 1-3 minutes.

35,000 ppm

Measured tailpipe exhaust concentration from warm carbureted gasoline engines without catalytic converters. (Greiner, unpublished field study, January 1997)

70,000 ppm

Typical tailpipe exhaust concentrations from cold gasoline engine during the first minute of a cold weather start. Concentrations decreased to 2 ppm after 17 minutes of running. (Greiner, unpublished field studies, January 1997.)

100,000 ppm

Smoke often reaches 10% (Ellerhorn). In less than one minute carboxyhemoglobin levels reach toxic levels of 75% HbCO (Ellenhorn).

Notes: 10,000 ppm (parts per million) = 1% by volume
Individual responses vary widely and are affected by respiration rate