Carbon Monoxide (CO) Gas Library
A structured overview of carbon monoxide (CO): what it is, where it comes from, why it’s dangerous, reference limits (for context), and the most common ways to detect it in homes, workplaces, and industrial sites.
Quick facts
CO is often described as the “silent killer” because you cannot reliably smell or see it. In real deployments, CO safety depends on proper detection and ventilation/control.
CO
Carbon monoxide
630-08-0
Common reference ID
Colorless
Odorless in practice
Mixes easily
Near similar density to air
Where CO comes from
CO is mainly produced by incomplete combustion. Common sources include fuel-burning heaters and furnaces, fireplaces, stoves, charcoal grills, gasoline or diesel engines, generators, forklifts, and vehicle exhaust in garages or loading bays.
- Boiler rooms, generator rooms, and mechanical spaces
- Parking garages and enclosed loading docks
- Kitchens with gas appliances and poor ventilation
- Fire scenes, welding/cutting operations, and confined spaces
When CO becomes a problem
Risk increases when combustion happens indoors or in semi-enclosed areas, when ventilation is insufficient, or when equipment is poorly maintained.
Practical reminder
Human senses are not reliable for CO. For safety decisions, use detectors and follow your local code.
Hazards and Health Risks
Carbon monoxide exposure is dangerous because it interferes with oxygen transport in the body. Symptoms can be non-specific and may be mistaken for fatigue or illness.
Why it’s toxic
CO can reduce oxygen delivery in the bloodstream. This is why even moderate exposure in enclosed spaces can become a serious hazard.
Common warning signs
Headache, dizziness, nausea, confusion, weakness, shortness of breath—especially when multiple people feel symptoms in the same area.
High-risk environments
Garages, boiler rooms, workshops with engines, confined spaces, and locations with ventilation failures.
Safety note
This page is for informational use. If you suspect CO exposure, move to fresh air and seek professional help immediately.
Reference limits and standards
CO limits vary by jurisdiction and scenario (workplace vs ambient air). The table below is a reference to help engineers and safety teams align alarms and controls. Always verify with your local code, authority having jurisdiction, and project requirements.
| Organization / Context | Averaging time | Limit | Notes |
|---|---|---|---|
| OSHA (Workplace) | 8-hour TWA | 50 ppm | Permissible exposure limit (reference) |
| NIOSH (Workplace guidance) | 10-hour TWA | 35 ppm | Recommended exposure limit (REL) |
| NIOSH (Ceiling) | Ceiling | 200 ppm | Do not exceed at any time |
| NIOSH IDLH | Immediate danger | 1,200 ppm | Immediately Dangerous to Life or Health (reference) |
| US EPA NAAQS (Outdoor air) | 8-hour / 1-hour | 9 ppm / 35 ppm | Ambient air standard (reference) |
How to use limits in real projects
In practice, alarm setpoints should be based on your risk assessment, occupancy, ventilation strategy, and the purpose of the detection system (personal safety vs ventilation control vs compliance reporting).
- Use multi-level alarms for fixed systems (warn / action / high)
- For ventilation control, consider both absolute level and rise rate
- Ensure calibration and bump-test procedures are executable
Common mistake
Copying a single “ppm threshold” from the internet without matching the detector type, environment, and code requirements can cause nuisance alarms or missed hazards.
Better approach
Use a deployment checklist and validate placement with airflow/occupancy conditions.
Detection basics
Most CO detectors and industrial CO transmitters use electrochemical CO sensors because they offer good selectivity and low power. For engineering work, the “best” sensor depends on environment, expected range, output requirements, and maintenance reality.
Electrochemical CO
Strong choice for ppm-level CO measurement. Often used in portable detectors, residential alarms, and fixed industrial transmitters.
Typical outputs: analog (mV), 4–20mA (via transmitter), UART/RS485 (via module)
MOS (Semiconductor)
Can be used for trend monitoring or cost-sensitive products, but may require stronger compensation to reduce cross-sensitivity and drift in real environments.
Best when you can calibrate well and accept broader selectivity.
System view
Detection is not only a sensor choice. Placement, airflow, alarm logic, calibration frequency, and maintenance determine real performance.
Treat the detector + environment + SOP as one system.
Practical selection questions
Are you building a product (OEM/ODM)?
Start from the interface and environment: required range, power budget, warm-up behavior, expected lifetime, and whether you can maintain calibration.
- Output: analog / digital / 4–20mA / RS485
- Compensation: temperature/humidity
- Calibration plan: bump test + periodic calibration
Are you deploying detectors (safety project)?
Decide whether you need portable units for people, fixed points for continuous monitoring, or both. Then design alarm responses: ventilation, shutdown, evacuation, and reporting.
- Fixed systems: controller + relays + BMS/SCADA
- Portable systems: personal alarms + logs
- Placement: where exposure occurs, not “where it looks easy”
Want a deployable short list (sensors + detectors + solution providers)? Use the CO Detection Guide or request recommendations.
Related CO resources
Use these pages to go deeper. The library page is intentionally concise; the guide pages cover deployment details.
For suppliers & solution providers
You can sponsor CO-related recommendation slots in the CO Detection Guide (sensors, detectors, providers). Sponsored placements are labeled clearly.
FREQUENT QUESTIONS
Frequently Asked Questions About Gas Detection Solutions
GasNose is a neutral knowledge base for gas detection. We publish practical guides that cover hazards, typical limits, detection methods, and deployment checklists. Some recommendation sections may include sponsored listings (clearly labeled) so engineers, OEM/ODM teams, and safety buyers can quickly compare sensor options, detector devices, and solution providers.
We do not manufacture sensors or turnkey systems. Instead, we help you choose the right approach and connect you with qualified suppliers. If you need recommendations for a specific gas (CO, H2S, NH3, CH4, VOC, refrigerants), tell us your application, environment, and target range.
What information should I provide to get accurate recommendations?
Please share: target gas, expected range (ppm/%LEL), environment (temperature/humidity, dust, corrosives), install type (portable vs fixed), output/interface requirements, certification needs (if any), and the deployment scenario (parking garage, boiler room, wastewater, HVAC machinery room, robotics, etc.). This helps avoid false alarms and poor sensor fit.
Can GasNose provide a turnkey gas detection solution?
We do not deliver turnkey engineering or on-site commissioning. However, for projects that need full solutions (alarm panels, BMS integration, fan interlocks, multi-point layouts, robotics deployments), we can list 1–3 capable solution providers and help route your inquiry to the right partner.
Do you recommend complete gas detectors (portable or fixed)?
Yes. We typically recommend 3–6 detector devices per gas page, grouped by use case (portable personal safety, confined space entry, fixed area monitoring, controller + relay interlock). If you need customized devices, we can also connect you with manufacturers who support private label/branding.
Can you recommend sensors for OEM/ODM integration?
Yes. For each gas page, we can list 3–6 sensor options across different technologies and packaging (bare sensors, modules, transmitters) so OEM/ODM teams can compare output types (analog, UART, I²C, RS485), operating conditions, and typical use cases.
What is GasNose and how are recommendations selected?
GasNose publishes practical gas detection guides (hazards → regulations → how to detect → recommendations). We prioritize real-world deployability: sensor principle fit (electrochemical/MOS/NDIR/PID/catalytic), stability, calibration practicality, and interface options. Sponsored listings are always labeled, and editorial content is written independently.
Request Recommendations / Partner Inquiry
GETTING STARTED
Tell Us Your Gas Detection Scenario — Get Practical Options Fast
GasNose helps you shortlist deployable options for gas sensors, detector devices, and qualified solution providers. We will suggest practical paths based on your application (fixed monitoring, portable safety, HVAC leak detection, confined spaces, or robotics patrol). Sponsored partners may appear in recommendations, and will be clearly labeled.
- Practical recommendations by gas type (CO, H2S, NH3, CH4, VOC, refrigerants…)
- OEM/ODM sensor options (modules, transmitters, digital/analog outputs)
- Detector device suggestions (portable & fixed) with use-case grouping
- Deployment checklist: placement, calibration, cross-sensitivity, maintenance
- Optional: connect you with qualified solution providers for turnkey projects
- Clear disclosure: sponsored listings are labeled; editorial remains independent
Enter Your Project Details
Share your target gas, range, environment, and installation type. We’ll respond with a short list of recommended sensor options, detector devices, and (if needed) solution providers.
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