Carbon monoxide, one of the most abundant pollutant gases, is indetectable to humans as it can not be seen, smelled, or tasted. Exposure to high levels of CO can cause CO poisoning leading to serious health issues, giving it the name “The Silent Killer”. CO monitoring is the most effective way to know if you are at risk of carbon monoxide exposure. This article covers information on carbon monoxide, its sources, permissible levels in the ambient air, health and environmental impact, possible corrective measures, need for carbon monoxide monitors as well as different methods of CO monitoring. What is CO? Carbon monoxide is a colorless, odorless, non-irritating, and tasteless poisonous gas found in the atmosphere. Incomplete combustion of carbon-containing fuels such as coal, gasoline, natural gas, oil, and wood produce this critical air pollutant. [Source:https://www.acadiainsurance.com/carbon-monoxide-poisoning-dont-let-sneak/] Carbon monoxide gas consists of one carbon atom and one oxygen atom. The molecular weight of carbon monoxide is similar to that of air about 28.01 g/mole. It is flammable and reacts vigorously with oxygen, acetylene, chlorine, fluorine, and nitrous oxide. Also, it is slightly soluble in water, blood serum, and plasma. Carbon monoxide in Atmosphere CO is naturally present in the atmosphere at very low concentrations of about 0.2 ppm which is not harmful to humans. CO is released naturally from the eruption of volcanoes, forest fires, etc. However, human activities are the biggest source of CO emissions. It remains in the atmosphere for about 2 months and then it eventually reacts with oxygen to form carbon dioxide. CO is produced due to incomplete combustion of fuels (combustion is when fuel reacts with oxygen to produce heat). If enough oxygen is not available for combustion, it results in the partial oxidation of carbon-containing compounds. During such combustion, carbon monoxide (CO) is produced instead of carbon dioxide (CO2).

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Carbon Monoxide (CO)
All you need to know about...

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All you need to know about Carbon MonoxideWHAT IS CO?
Carbon Monoxide is a colorless, odorless, non-irritating
and tasteless poisonous gas found in the atmosphere. It
consists of one carbon atom and one oxygen atom.
It produced by incomplete combustion of carbon-
containing fuels such as coal, gasoline, natural gas, oil, and
wood.
CO is naturally present in the atmosphere at very low, safe concentrations of about 0.2
ppm. It remains in the atmosphere for about 2 months before eventually reacting with
oxygen to form carbon dioxide (CO2). It is typically highest during the winters.

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All you need to know about Carbon MonoxideFORMATION OF CO
CO is produced due to incomplete combustion of fuels (combustion is when fuel reacts
with oxygen to produce heat). If enough oxygen is not available for combustion, it results
in the partial oxidation of carbon-containing compounds results in production of CO
instead of CO2 .
Complete Combustion
Incomplete Combustion

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All you need to know about Carbon MonoxideSOURCES
Natural Sources: Volcanoes, bush / forest fires, lightening.
Anthropological Sources:
● Exhaust from cars, trucks, airplanes, and boats, etc.
● Burning of biomass for cooking
● Power generation
● Appliances such as heaters, barbeques, gas stoves,
gas water heaters, fireplaces, etc.
● Mining of metal ore and coal, metal manufacturing
● Food processing industries
● Extraction and refining of oil and gas

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All you need to know about Carbon Monoxide
The breakpoints concentrations describing the quality of air based on the CO concentrations
(mg/m3) for different countries are:
India (8-hr) US (24-hr) China (24-hr) EU (8-hr)
AQI Category
Break point
concentration
AQI Category
Break point
concentration
AQI Category
Break point
concentration
AQI Category
Break point
concentration
Good 1 Good 5 Excellent 2 Very low 5
Satisfactory 2 Moderate 11 Good 4 Low 7.5
Moderately
polluted
10
Unhealthy for
sensitive
14
Lightly
Polluted
14 Medium 10
Poor 17 Unhealthy 18
Moderately
Polluted
24 High 20
Very Poor 34 Very Unhealthy 35
Heavily
Polluted
36 Very high 20+
Severe 34+ Hazardous 58
Severely
Polluted
36+
Source: National Ambient Air Quality Index, CPCB (Oct 2014)
PERMISSIBLE LIMITS

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All you need to know about Carbon MonoxideADVERSE IMPACTS
● CO impairs the oxygen-carrying capacity of the
body by replacing the oxygen in the bloodstream and
binding itself to hemoglobin to form
carboxyhemoglobin (COHb).
● Inhaling CO in higher amounts causes oxygen
starvation which affects vital organs like heart, brain,
and nervous system.
● Initial symptoms of CO poisoning include headache, dizziness, weakness, nausea and
fatigue. Prolonged or high CO exposure can cause vomiting, chest pain, loss of
consciousness and may lead to coma or death if high exposure continues.
HEALTH IMPACTS OF CO

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All you need to know about Carbon MonoxideADVERSE IMPACTS
ENVIRONMENTAL IMPACTS OF
CO
● CO indirectly contributes to global
warming by reacting with hydroxyl radical
in the atmosphere that are important in
reducing the presence of strong
greenhouse gases.
● CO also contributes to the formation of
ozone in the air which is another critical
air pollutant.
● Reaction of CO in atmosphere leads to
hydroxyl conversion and ozone formation.
CO + OH ➝ CO2 + H
H + O2 ➝ HO2
HO2 + NO ➝ OH + NO2
NO2 + sunlight ➝ NO + O
O + O2 ➝ O3
Net: CO + 2O2 ➝ CO2 + O3
The reactions of CO in the atmosphere:

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All you need to know about Carbon MonoxideCORRECTIVE MEASURES
The primary action is CO monitoring i.e. to measure how much CO concentrations you are
exposed to. In addition to this following corrective measures can be taken:
● If you detect the presence of high CO levels, get some fresh air, or provide proper
ventilation.
● Have a walk, use bicycles or public transport whenever possible.
● Promote the use of alternative fuels.
● Avoid keeping your vehicle idle for long.
● Avoid areas with traffic congestions. Breathing such polluted air daily also leads to
health effects in the long run.
● Avoid using fuel-burning appliances such as generators or engines in low ventilated
areas.
● Proper usage and preventive maintenance of heating components such as gas or
water heaters or any other gas, oil or coal-burning appliances, etc.

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All you need to know about Carbon MonoxideMONITORING METHODS
Nondispersive infrared absorption (NDIR)
When the gas sample is exposed to infrared radiation,
CO molecules present in the gas sample absorbed the
infrared radiation and is measured by the detector in a
non-dispersive photometer.
Semiconductor
When sensor is exposed to air sample, the CO molecules
react on the metal oxide surface of the sensor and
dissociate into charged ions which alter the resistance of
the film which is measured and converted to the CO
concentration.

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All you need to know about Carbon MonoxideMONITORING METHODS
Electrochemical
CO monitors working on the
electrochemical principle are operated
based on diffusion of carbon monoxide gas
into the sensor which results in the
production of an electrical signal
proportional to the CO concentration.
It allows accurate measurement of even low
concentrations of carbon monoxide, which is
essential in carbon monoxide monitoring in
the ambient conditions.

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All you need to know about Carbon MonoxideOIZOM’S PRINCIPLE
Oizom’s POLLUDRONE measures more than 30
parameters including gaseous pollutants like CO,
SO2, NO, NO2; dust particulates like PM2.5, PM10,
noise and weather parameters like rainfall, wind
speed and wind direction.
Most of the sensors measuring gases including
carbon monoxide work on the principle of
electrochemical sensing.
Real-time monitoring of CO levels helps in
calculating air quality index to deliver health
advisories as well as formulating an action plan to
meet standards.