Customers often ask about the difference between volatile organic compound (VOC) sensors and carbon dioxide (CO2) sensors. While both can be used to measure indoor air quality they are not interchangeable.
CO2 sensors and VOC sensors measure very different things.
The challenge is that when searching for sensors to measure indoor air quality, both work, and both have their strengths and weaknesses. So the question becomes, when measuring IAQ, which sensor is right for you?
Understanding CO2 and VOCs: Why Detection Matters
Carbon dioxide and volatile organic compounds are two critical components in air quality that can significantly impact human health and comfort.
CO2 is a naturally occurring gas primarily produced by human respiration and combustion processes. While it is harmless in small quantities, elevated levels in enclosed spaces can lead to drowsiness, decreased cognitive function, and long-term health concerns.
VOCs, on the other hand, are a group of chemicals released into the air from various sources, such as cleaning products, paints, and building materials. These compounds can have adverse effects ranging from mild irritation to more severe conditions like respiratory issues, headaches, and even long-term chronic illnesses when exposure is prolonged.
The detection of both CO2 and VOCs is essential for maintaining healthy indoor environments, especially in workplaces, schools, and residential spaces where people spend extended periods of time. Monitoring these gases allows building managers and occupants to take necessary actions such as increasing ventilation or reducing the use of certain materials to ensure air quality remains within safe limits.
The importance of detecting these compounds lies in their potential to compromise both health and productivity, making sensor technology a vital tool for improving overall well-being.
Why measure Carbon Dioxide?
For many years, CO2 has become the "go-to" for measuring indoor air quality across homes, classrooms, or commercial buildings. CO2 sensor technologies are stable, they are not subject to short term drift, and output signals can be used to control the fresh air exchange of an HVAC system.
Carbon dioxide levels indoors give an indication of how many occupants are in an enclosed space. The more people, the more fresh air that is required for maintaining comfortable air quality. But just as importantly, high CO2 levels have been shown to be an indirect indicator of high levels dust, mold, germs, bacteria, VOCs and other contaminants that can impact human health.
CO2 levels of 1,000 ppm (parts per million) or more are known to directly affect cognitive ability, ailments, asthma, productivity and even the ability to make strategic decisions. Aside from these health effects, in the case where occupants may be around tanks of compressed CO2, concentrations above 3% or 30,000 ppm can be life-threatening.
What does a CO2 Sensor detect?
When it comes to sensing, most carbon dioxide sensors are designed to monitor and detect for the presence of carbon dioxide, based on NDIR technology.
CO2 sensors are used across a wide range of industries like indoor air quality because too much CO2 can be hazardous to health. For example, moderate to high levels of carbon dioxide can cause headaches and fatigue, and higher concentrations can produce nausea, dizziness, and vomiting. At higher levels, loss of consciousness and fatalities may occur.
CO2 Sensors to Monitor Indoor Air Quality
CO2 sensors play a vital role in indoor air quality (IAQ) monitoring across a variety of settings, from commercial buildings and schools to industrial facilities and residential homes. By continuously tracking carbon dioxide levels, these sensors help maintain healthy indoor environments by ensuring proper ventilation.
In spaces with fluctuating occupancy, such as offices, conference rooms, and classrooms, CO2 sensors can trigger HVAC systems to increase ventilation when CO2 levels rise, reducing the risk of poor air quality and enhancing occupants' comfort and cognitive function. This demand-controlled ventilation strategy not only improves air quality but also leads to energy savings by optimizing ventilation based on real-time needs.
As a control, a CO2 sensor can also activate an alarm or mitigation strategy (activate filters or ventilation). Because carbon dioxide is an inert gas, it will not cause a VOC sensor to react. Both approaches can be applied to a demand-controlled ventilation strategy, but the results may be very different.
The Role of VOC Sensors in Detecting Airborne Contaminants
VOCs are molecules of hazardous chemicals in the air. Exposure to these chemicals can directly and negatively impact your health. Thus, the need for monitoring VOC's can be critical - especially indoors or in enclosed areas.
The Environmental Protection Agency classifies a volatile organic compounds as "any compound of carbon that participates in atmospheric photochemical reactions." By definition, this classification eliminates carbon monoxide, carbon dioxide, carbonates, ammonium and other gases since they do not chemically react with other molecules.
VOC's are commonly produced by a variety of household products such as:
- Paints
- Cosmetics
- Scented candles
- Fragrances
- New furniture
- Cleaning products
- Cooking sprays
- Plastic products like children's toys
- New carpet and drywall
In fact, any time you read the term "off-gassing" or notice a smell from a product brought into your home, chances are you are being exposed to VOCs.
Because these products are used in indoor air environments like homes, offices, or classrooms VOCs can contaminate any fresh air. They can cause eye and throat irritation, liver and kidney damage, cancer or severe ailments depending upon the amount of exposure.
In order to combat the amount of VOCs indoors, several strategies may be used:
- HEPA air filters
- Avoid purchasing products with high VOC levels
- Purchase used furniture
- Hardwood or laminate floors
- Change to low VOC cleaning products
However, even these small acts towards reducing the gases can not always be enough. Since long-term VOC exposure can lead to severe health effects, the only way to accurately monitor the level of VOCs in a room is with a VOC sensor.
VOC sensors, which stands for volatile organic compound sensors, are designed to detect and measure the presence of various volatile organic compounds in the surrounding environment. Volatile organic compounds are organic chemicals that can easily vaporize and enter the air we breathe, often released from products are processes.
VOC sensors such as the IAQ-2000 or IAQ-0001 measure the concentration of these molecules and can provided a warning when concentrations get too high and increased ventilation is needed.
This sensor shown is a sensitive, metal oxide semiconductor (MOS) that is able to detect a broad range of VOCs. This means that the sensor provides a total VOC concentration, not specific molecules or compounds.
VOC Sensors: Where Are They Most Effective?
VOC sensors are most effective in environments where harmful chemicals and pollutants are present, making them critical tools for monitoring air quality in industrial, commercial, and residential spaces.
In industrial settings such as manufacturing plants, laboratories, and chemical processing facilities, VOC sensors are used to detect the presence of volatile organic compounds emitted by solvents, adhesives, and other materials. These compounds can be hazardous to workers' health, leading to respiratory problems, headaches, and long-term illnesses if exposure is not properly controlled. By continuously monitoring VOC levels, these sensors help ensure compliance with occupational health and safety standards, enabling early detection and prevention of harmful exposure.
VOC sensors are also valuable in residential and commercial settings where everyday products like cleaning agents, paints, and building materials can release harmful gases. In homes, schools, and office buildings, these sensors can detect indoor pollutants that affect occupants' health and well-being. VOC sensors are particularly effective in identifying poor indoor air quality in newly constructed or renovated spaces where off-gassing from construction materials is common. Their ability to measure a broad spectrum of pollutants makes VOC sensors essential for maintaining healthy indoor environments and protecting occupants from both short-term irritation and long-term health risks.
Can a VOC Sensor measure Carbon Dioxide?
No, a VOC sensor cannot directly measure CO2. VOC sensors are specifically designed to detect and measure volatile organic compounds, which are organic chemicals that can easily vaporize into the air.
Carbon dioxide, on the other hand, is a non-volatile gas and is not considered a volatile organic compound. While both VOCs and carbon dioxide can contribute to indoor air quality issues, they are distinct substances with different properties and detection methods.
To measure carbon dioxide levels, you would need a sensor specifically designed for that purpose.
Note that while some VOC indoor air quality meters claim to measure CO2, they do not. Instead they perform a rough calculation of the CO2 levels based on VOC measurements.
So, if you want to measure carbon dioxide levels, you should look for a CO2 sensor rather than a VOC sensor.
Key Differences Between CO2 and VOC Sensors
CO2 sensors and VOC sensors are designed to detect different types of gases, and their core functionality reflects this distinction. A CO2 sensor measures the concentration of carbon dioxide in the air in offices, schools, or anywhere ventilation needs to be adjusted based on occupancy levels and indoor air quality.
VOC sensors, on the other hand, detect a wide range of volatile organic compounds, including formaldehyde, benzene, and acetone, among others.
Unlike CO2 sensors, which focus on one specific gas, VOC sensors provide a broader measure of air quality by detecting multiple potentially harmful substances. This makes VOC sensors ideal for spaces where pollutants from cleaning supplies, paints, or building materials may be present, allowing for early detection and mitigation of harmful chemical exposure.
While both sensors are used to monitor indoor air quality, their key difference lies in what they measure—CO2 sensors focus on a single gas critical for ventilation control, while VOC sensors capture a range of harmful chemicals that can affect health in various ways.
Choosing the Right Sensor: CO2 vs. VOC for Your Needs
When deciding between a CO2 sensor and a VOC sensor, the choice depends on the specific air quality challenges and the environment in which the sensor will be used.
If the primary concern is ventilation control and monitoring occupancy in enclosed spaces like offices, classrooms, or conference rooms, a CO2 sensor is the better option. On the other hand, if the air quality concern involves exposure to multiple harmful chemicals or pollutants, such as in environments with high use of cleaning agents, paints, or industrial solvents, a VOC sensor would be more appropriate.
VOC sensors are particularly useful in newly constructed or renovated spaces, as well as industrial settings where various volatile organic compounds may be present.
Ultimately, choosing the right sensor comes down to understanding the specific air quality risks in your environment and selecting the sensor that best addresses those needs.
Because CO2 sensors are often an alternative measure for VOC sensing, it is important to recognize that a key difference is in the contaminants being measured. While VOC sensors can provide indication of potentially harmful molecules, they do not give an overall measurement of indoor air quality.
Overall, the real delineation between CO2 vs. VOC sensors comes down to answering the following questions:
- What are you looking to measure?
- Do you need to regulate what you are measuring?
- How would you like this data to be shown?
Cost and Efficiency: Comparing CO2 and VOC Sensors
When comparing the cost and efficiency of CO2 and VOC sensors, it’s essential to consider both their intended use and technological complexity.
CO2 sensors tend to be more affordable due to their relatively simple and focused design. These sensors are often based on non-dispersive infrared (NDIR) technology, which allows them to efficiently and accurately detect carbon dioxide levels. Their cost-effectiveness, combined with their precision in monitoring CO2 for ventilation control, makes them a popular choice in environments like offices, schools, and residential spaces where maintaining proper air exchange is crucial. Additionally, CO2 sensors have a long operational life and require minimal maintenance, contributing to their overall cost efficiency.
VOC sensors, however, are typically more expensive due to their broader detection capabilities. They need to monitor a wide range of chemical compounds, requiring more advanced sensor technology such as metal-oxide semiconductors (MOS) or photoionization detectors (PIDs).
While VOC sensors provide more comprehensive air quality data, detecting multiple pollutants beyond CO2, they may also require more frequent calibration and maintenance to ensure accuracy. This makes VOC sensors more costly upfront and in terms of long-term operation, though they offer a wider scope of protection in environments where exposure to hazardous chemicals is a concern. When evaluating cost and efficiency, the decision comes down to whether precise CO2 monitoring or broader pollutant detection is the primary need.
Future Trends in Air Quality Sensors
The future of air quality sensing technology is defined by increased accuracy, greater connectivity, and the integration of smart technologies. As environmental awareness and regulations around air quality grow, sensor manufacturers are pushing the boundaries of what is possible in detecting airborne pollutants.
One of the most significant trends is the development of multi-sensor systems that can simultaneously detect a wide range of gases, including CO2, VOCs, particulate matter, and other hazardous pollutants. These advanced sensors are becoming smaller, more energy-efficient, and cost-effective, enabling their integration into everyday devices such as smartphones, HVAC systems, and smart home assistants.
This shift towards ubiquitous air quality monitoring will give individuals and businesses real-time insights into their environments, empowering them to make immediate adjustments to improve air quality.
Another trend is the rise of AI and machine learning in air quality sensing. These technologies can process vast amounts of data from sensors to predict air quality issues before they become a problem, allowing for preemptive measures to be taken. Additionally, wireless connectivity, through IoT (Internet of Things) networks, is enabling sensor data to be aggregated and analyzed on a broader scale, leading to city-wide or regional air quality management systems.
As air quality sensing technology becomes more sophisticated, we can expect more tailored solutions for specific industries, greater environmental monitoring, and increased public access to air quality data, all contributing to healthier indoor and outdoor environments.
For more information on CO2Meter.com sensing technologies or indoor air quality devices contact us today.