Carbon Monoxide Levels & Dangers

Here is some information from the National Comfort Institute (NCI) regarding carbon monoxide levels and the dangers associated with it.

CO Level
1-4 ppm
Normal levels in human tissues produced by body.
3-7 ppm
14% increase in the rate of admission in hospitals of non-elderly for asthma. (Sheppard-1999)
5-6 ppm
Significant risk of low birth rate if exposed during last trimester (Ritz & Yu-1999)
5 ppm
1st visual display on low level CO monitor.
9 ppm
ASHRAE standard for allowable spillage from vented appliances, indoors, for 8 hours exposure daily. EPA standard for outdoors for 8 hours and a maximum 3 times per year. (Clean Air Act)
10 ppm
Outdoor level of CO found associated with a significant increase in heart disease deaths and hospital admissions for congestive heart failure. (JAMA, Penny) 1st ambient level occupants should be notified-NCI Protocol
15-20 ppm
First level World Health Organization lists as causing impaired performance, decrease in exercise time and vigilance. 1st Alarm level for NSI 3000 Low Level CO Monitor-5 minutes
25 ppm
Maximum allowable in a Parking Garage (International Mechanical Code)
27 ppm
21% increase in cardio respiratory complaints (Kurt-1978)
30 ppm
Earliest onset of exercise-induced angina (World Health Organization). 1st visual display on UL2034 approved CO Alarm-Must not alarm before 30 days
35 ppm
US NIOSH recommended 8 hour maximum workplace exposure. EPA standard for outdoors for 1 hour and a maximum of 1 time per year. Many fire departments wear breathing apparatus before entering 2nd ambient level. Occupants should be notified and space ventilated. 2nd Alarm level for NSI 3000 Low Level Monitor-5 minutes
CO Level
50 ppm
US OSHA recommended 8 hour maximum workplace exposure Maximum NCI level for Unvented appliances
70 ppm
1st Alarm level of UL2034 approved CO Alarms- 2-4 hours 3rd Alarm level for NSI 3000 – 30 seconds NSI 3000 Low Level Monitor cannot be silenced by reset button
100 ppm
Maximum NCI CO level during run cycle in all vented appliances(stable) Maximum NCI CO for all oil appliances
200 ppm
First listed level(established in 1930) healthy adults will have symptoms-headaches, nausea NIOSH & OSHA recommend evacuation of workplace Maximum “Air Free” CO for vented water heater and unvented heaters (ANSI Z21) UL approved alarms must sound between 30 – 60 minutes(NSI 3000 – 30 seconds)
400 ppm
Healthy adults will have headaches within 1-2 hours. Life threatening after 3 hours Maximum “Air Free” CO in all vented heating appliances (ANSI Z21) Maximum EPA levels for industrial flue exhaust UL Alarms must alarm within 15 minutes (NSI 3000 – 30 seconds) Maximum recommended light-off CO for all appliances – NCI (except oil)
800 ppm
Healthy adults will have nausea, dizziness, convulsions within 45 minutes. Unconscious within 2 hours then Death (established in 1930). Maximum “Air Free” CO for unvented gas ovens (ANSI Z21) 800 ppm+ Death in less than one hour
2000 ppm
EPA standard for new vehicle emissions
3000 ppm+
Typical emissions from propane lift trucks, gasoline powered tools etc. Death in less than 30 minutes.

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