Carbon monoxide, one of the most abundant pollutant gases. The gas is indetectable to humans as one can not see, smell, or taste. However, 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 one is at risk of carbon monoxide exposure. Meanwhile, this article covers information on CO, its sources, permissible levels in the ambient air, health and environmental impact, possible corrective measures, the need for CO monitors, and different measurement methods.
What is CO?
Carbon monoxide is a colorless, odorless, non-irritating, tasteless, poisonous gas found in the atmosphere. Incomplete combustion of carbon-containing fuels such as coal, gasoline, natural gas, oil, and wood produces this critical air pollutant.
In other words, Carbon monoxide gas consists of one carbon atom and one oxygen atom. The molecular weight of CO is similar to that of air, about 28.01 g/mole. It is also 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
Above all, CO is naturally present in the atmosphere at low concentrations of about 0.2 ppm, which is not harmful to humans. Also, CO is released naturally from volcanoes, forest fires. However, human activities are the Biggest Source of CO emissions. It remains in the atmosphere for about two months, and then it eventually reacts with oxygen to form carbon dioxide.
Incomplete combustion of fuels (when fuel reacts with oxygen to produce heat) produces CO in the atmosphere. Indeed, if enough oxygen is not available for combustion, it results in the partial oxidation of carbon-containing compounds. Carbon monoxide (CO) produces during such combustion instead of carbon dioxide (CO2).
The levels of carbon monoxide are typically highest during winters as cold temperatures inhibit the combustion processes resulting in higher CO formation. Additionally, the meteorological conditions during winters trap the pollutants close to the ground. The use of gas furnaces and heaters increases in this season, adding to CO emissions. According to the Center for Disease Control (CDC), at least 430 people die in the U.S. from accidental CO poisoning.
Five reasons why CO monitoring is important?
- Combustion sources such as vehicles, gas heaters, generators, furnaces in enclosed places, and many such familiar sources are present everywhere to add to the carbon monoxide levels in the atmosphere.
- CO is smellless, tasteless, and not visible to the naked eye. This makes it undetectable by humans even at higher levels making it a “silent killer.”
- Carbon Monoxide poisoning is lethal as it hinders the ability of the blood to carry oxygen to vital organs such as the heart and brain.
- CO monitoring is an efficient way to prevent poisoning. It also helps detect the buildup of CO levels and provides alerts.
- Real-time carbon monoxide monitoring helps calculate the air quality index to deliver health advisories and formulate an action plan to meet standards.
Oizom’s working principle for Carbon Monoxide monitoring
Oizom’s POLLUDRONE measures more than 30 parameters some of the gaseous pollutants like carbon monoxide (CO), sulfur dioxide (SO2), nitric oxide (NO), nitrogen dioxide (NO2), dust particulates like PM2.5, PM10, noise, and weather parameters like rainfall, wind speed, and wind direction. Indeed, most of the sensors measuring gases, including carbon monoxide, work on the principle of electrochemical sensing. The active sampling-powered sensor-based air quality monitor POLLUDRONE is deployed across several cities, campuses, and universities. Polludrone helps draw actionable insights to tackle the rise in ambient carbon monoxide concentrations. Read more on the air pollution case studies.
What are the Carbon Monoxide Sources
Here are the three major sources of carbon monoxide in the atmosphere.
1> Natural
Natural sources such as volcanoes, bush/forest fires, the metabolism of animals, and even lightning lead to carbon monoxide emissions.
2> Anthropogenic
Due to the incomplete combustion of fuel in cars, trucks, airplanes, and boats, vehicular exhaust is the Primary Source of Carbon Monoxide. Additional sources include breathing in tobacco smoke, burning biomass for cooking, equipment, or appliances such as heaters, barbeques, gas stoves, gas water heaters, and fireplaces.
3> Industrial
The primary industrial source of carbon monoxide is fuel combustion such as coal, natural gas, and coke in industrial plants. In addition, various industrial processes such as metal manufacturing, mining of metal ore and coal, food processing industries, power generation, oil and gas extraction and refining functions oil and gas from either land or sea, production of chemicals, manufacturing of concrete and plaster also contribute to CO emission.
What are the Permissible levels of CO in atmosphere?
The breakpoints concentrations describing air quality based on the carbon monoxide concentrations for different countries are given below. For example, in India, the daily average CO levels of up to 2 mg/m3 are considered satisfactory.
Table: Breakpoints of CO (mg/m3)
| India (8-hr) | US (24-hr) | China (24-hr) | EU (8-hr) | |||
| AQI Category | Breakpoint concentration | AQI Category | Breakpoint concentration | AQI Category | Breakpoint concentration | AQI Category |
| Good | 1 | Good | 5 | Excellent | 2 | Very low |
| Satisfactory | 2 | Moderate | 11 | Good | 4 | Low |
| Moderately polluted | 10 | Unhealthy for sensitive | 14 | Lightly Polluted | 14 | Medium |
| Poor | 17 | Unhealthy | 18 | Moderately Polluted | 24 | High |
| Very Poor | 34 | Very Unhealthy | 35 | Heavily Polluted | 36 | Very high |
| Severe | 34+ | Hazardous | 58 | Severely Polluted | 36+ |
What are the Health & Environmental Impact of carbon monoxide?
1> Health Impact
Firstly, Carbon Monoxide is known for its harmful effect on human health. CO has a higher affinity (200 times) than oxygen to hemoglobin (Hb), the protein in the blood that carries oxygen from the lungs to cells throughout the body. As a result, it replaces the oxygen in the bloodstream and binds itself to hemoglobin to form carboxyhemoglobin (COHb) which impairs the body’s oxygen-carrying capacity. Moreover, inhaling CO in higher amounts causes oxygen starvation, affecting vital organs like the heart, brain, and nervous system.
It is more dangerous because humans cannot detect higher levels of CO as it is colorless, smellless, and tasteless. In addition, people suffering from some heart disease are even more vulnerable. Heart patients already have a reduced ability to get oxygenated blood to their hearts when they need more oxygen than usual. So, short-term exposure to elevated CO may result in more critical health issues in these situations.
Initial symptoms of CO poisoning may include flu-like symptoms such as headache, dizziness, weakness, nausea, and fatigue. The symptoms may advance to vomiting, loss of consciousness, and collapse in prolonged or high exposures. Further, it may lead to coma or death if high exposures continue. In addition, people with coronary heart disease may suffer from chest pain.
2> Environmental Impact
Carbon monoxide is a very weak direct greenhouse gas, but it reacts with the hydroxyl radicals in the atmosphere and reduces their abundance. Moreover, hydroxyl radicals are important in the atmosphere as it reacts with potent greenhouse gases and help reduce their effect on global warming. Thus, the CO emitted into the atmosphere indirectly contributes to global warming. CO also contributes to ozone formation in the air, another critical air pollutant.
The reactions of CO in the atmosphere leading to hydroxyl conversion and ozone formation are:
CO + OH ➝ CO2 + H
H + O2 ➝ HO2
HO2 + NO ➝ OH + NO2
NO2 + sunlight ➝ NO + O
O + O2 ➝ O3
Net: CO + 2O2 ➝ CO2 + O3
Possible corrective measures
The primary action is CO monitoring, i.e., to measure how much CO concentrations are in the surroundings. In addition to this following corrective measures can be taken:
- If one detects high CO levels, get some fresh air, also provide proper ventilation.
- Have a walk, use bicycles or public transport whenever possible.
- Additionally, promote the use of alternative fuels.
- Also, avoid keeping vehicles idle for long.
- Avoid areas with traffic congestion. 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.
- Also, appropriate usage and maintenance of heating components.
Measurement methods of CO monitoring
Different working principles for carbon monoxide monitoring in the ambient environment are non-dispersive infrared absorption (NDIR), semiconductors, and electrochemistry.
Non-dispersive infrared absorption (NDIR) – Carbon monoxide absorbs infrared radiation at a particular frequency. Therefore, when the gas sample is exposed to infrared radiation, the infrared radiation absorbed by the CO molecules present in the gas sample is measured by the detector in a non-dispersive photometer. However, using this principle in CO monitors may result in potential interferences from other gases that absorb infrared radiation similar to CO.
Semiconductor – When a metal oxide semiconductor-based carbon monoxide monitor is exposed to an air sample, the CO molecules react on the metal oxide surface of the sensor and dissociate into charged ions which alter the film’s resistance. As a result, this interaction is measured as a signal and converted to the gas concentration. However, such CO monitors’ energy consumption is higher than other CO monitors.
Electrochemical – CO monitors working on the electrochemical principle are operated based on the diffusion of carbon monoxide gas into the sensor. As a result, it produces electrical signals proportional to the CO concentration. Therefore, it allows accurate measurement of even low concentrations of carbon monoxide, which is essential in CO monitoring in ambient conditions.
Among all the above principles of CO monitoring, applications like ambient air monitoring prefer carbon monoxide monitors based on electrochemistry. As a result, they yield more accurate CO concentrations and are inexpensive compared to the others.
Here are some of the common questions people ask related to Carbon Monoxide
What is the chemical formula of Carbon monoxide?
The chemical formula of carbon monoxide is CO. It consists of one carbon atom and one oxygen atom bonded through a triple bond. The molecular weight of carbon monoxide is similar to that of air about 28.01 g/mole. The structural formula of carbon monoxide is:
: C ☰ O :
What does Carbon monoxide smell like?
Carbon monoxide is an odorless gas. Being one of the most abundant pollutant gases, it is undetectable 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”.
Is there carbon monoxide in ambient air? What is the normal CO level in the ambient air?
The concentration of carbon monoxide in the atmosphere is very low, i.e. about 0.2 ppm, which is not harmful to humans independently. Natural sources of CO are volcanoes, forest fires.
How is carbon monoxide produced?
CO is produced due to the incomplete combustion of fuels like wood, coal, oil, kerosene, and natural gas. The absence of a sufficient quantity of oxygen for combustion results in the partial oxidation of carbon-containing compounds. Carbon monoxide (CO) is produced instead of carbon dioxide (CO2).
What would cause carbon monoxide in a home? OR Sources of carbon monoxide at home
Any product or equipment with internal combustion can release carbon monoxide gas indoors. The most common sources are fireplace chimneys, oil or gas-fired furnaces, gas stoves, gas water heaters, dryers powered by any fuel, generators and other gasoline-powered equipment, tobacco smoke, worn or poorly adjusted and maintained combustion devices (e.g., boilers, furnaces), automotive exhaust from an idle car running in the garage, vehicle exhaust from nearby roads, or parking areas.
What are the levels of carbon monoxide at home, indoors?
Average levels of carbon monoxide gas in homes without gas stoves vary from 0.5 to 5 ppm parts per million (ppm). While the levels near properly adjusted gas stoves are often 5 to 15 ppm, those near poorly adjusted stoves may be 30 ppm or higher.
[source : epa.gov]
What level of CO is normal? OR What CO level is dangerous to my health?
The health effects of carbon monoxide gas depend on the CO concentration inhaled and length of exposure, as well as each individual’s health condition. Most people will not experience any symptoms from prolonged exposure to approximately 1 to 70 ppm carbon monoxide gas. However, some heart patients might experience an increase in chest pain. Symptoms become more noticeable and can include headache, fatigue, and nausea at concentrations higher than 70 ppm. At carbon monoxide levels sustained above 150 to 200 ppm, disorientation, unconsciousness, and death are also possible.
What are the symptoms of carbon monoxide poisoning?
Initial symptoms of CO poisoning may include flu-like symptoms such as headache, dizziness, weakness, nausea, and fatigue. This may advance to vomiting, loss of consciousness, and collapse in prolonged or high exposures. It may lead to coma or death if high exposures continue. People with coronary heart disease may suffer from chest pain. In the case of carbon monoxide emission indoors, when people are asleep, they would be unlikely to wake by these symptoms, thereby increasing the risk of death unless they have a CO monitor to rely on to wake them through an alarm.
Who is at risk from CO poisoning?
Everyone is at risk for CO poisoning. Infants, the elderly, people with chronic heart disease, anemia, or breathing problems are more likely to get sick from CO.
How do I know if carbon monoxide is present?
Natural gas or LPG has a characteristic odor that quickly alerts its presence. However, carbon monoxide does not have any smell or fume, or color for visibility and detection. Carbon monoxide can quickly enter through normal breathing without causing any irritation to the nose or throat. When inhaled unknowingly, the carbon monoxide molecules replace the oxygen in blood cells, starving the organs of the needed oxygen.
CO is undetectable 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”. The best way to detect the presence of carbon monoxide exposure is through carbon monoxide monitoring. When placed indoors, it works like a smoke alarm, sampling the air you are exposed to and creating a loud alarm when harmful levels of carbon monoxide gas are detected.
How do you monitor CO levels?
The concentration of carbon monoxide gas is monitored using expensive conventional analyzers and low-cost sensors. The CO monitors must be strategically placed based on the application. For example, if the purpose is to detect the presence of CO indoors, the carbon monoxide monitor must be placed where the people majorly stay like their bedrooms. Suppose the purpose is to monitor carbon monoxide gas emissions from vehicle exhaust at a traffic junction. In that case, the CO monitor must be placed at the center of the junction near the Source.
What to do if carbon monoxide Is detected?
If any symptoms of carbon monoxide poisoning are identified or the CO monitor alerts you of a possible leak, immediately leave your home to get some fresh air, or provide proper ventilation. The treatment for carbon monoxide poisoning is high-dose oxygen. Using higher atmospheric pressure around the body can speed up the effectiveness of the high-dose oxygen treatment.
About Oizom
Oizom is an environmental IoT company offering data-driven environmental solutions for better decision-making. With our sensor-based hardware, we monitor various environmental parameters like air quality, noise, odor, radiation, weather conditions, etc. Our data analytics platform derives many actionable insights for authorities, communities, and industries. Oizom strives to play an essential role in a sustainable future through smart environmental solutions and data science. Read more here.
