Proactive vs. reactive CO2 detection for improved indoor health


Harmful levels of hydrocarbons and carbon monoxide have been known for many years to moderately or even severely impair health and well-being. The effects of high concentrations of carbon dioxide (CO2) in confined interior spaces has only become a serious issue in the last two decades. Recent technological advances to measure CO accurately and cheaply2 enable developers to reactively or proactively address the negative aspects of unhealthy CO levels2.

A proactive response will quickly provide an improved environment for those who would otherwise be exposed to these high levels. Stakeholders range from companies that do not exclusively conduct their business at network meetings, to suppliers of ventilation and filtration systems, to building designers and owners, as well as those responsible for building maintenance. Instead of reacting to government regulations, industry leaders should take a proactive leadership position.

Effects of too much CO2 levels

CO is produced as a by-product of respiration2 Indoors, levels increase as population density increases. At different concentrations, CO2 can affect the human body. As shown in illustration 1, the effects range from complaints of drowsiness to harmful effects of oxygen starvation. In between, performance and occupant alertness are seriously compromised.

illustration 1 CO2 is a key parameter for indoor air quality, i.e. for the comfort and well-being of the occupants, CO2 Measurements are important. Source: Wisconsin Department of Health Sciences, Fisk et al

A few years ago, the United States Occupational Safety and Health Administration (OSHA) regulatory agency of the US Department of Labor established a Permissible Exposure Limit (PEL) for CO2 of 5,000 parts per million (ppm). Here 0.5% CO2 in air averaged over an 8 hour workday (time weighted average or TWA). The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) has also recommended that concentrations of CO2 be kept below 1,000 ppm in classrooms and below 800 ppm in offices for many years.

More recently, the California Building Standards Code (California Code of Regulations, Title 24) or simply CA Title 24 Legislation requires compliance. While CO2-based demand controlled ventilation (DCV) has been part of Title 24 since 1996 and became mandatory for certain high density applications in 2005. As an airborne disease, COVID-19 has drawn increased attention to air filtration and the concentration of people in small spaces. Many existing CO2 Sensors still do not meet current accuracy requirements for effective DCV implementations.

Based on photoacoustic spectroscopy (PAS) technology, Infineon’s XENSIV PAS CO2 Sensor provides the performance – ±30ppm ±3 percent of reading – to meet Title 24 in a small form factor of 14mm x 13.8mm x 7.5mm. With plug-and-play capabilities, the CO2 Sensor sets an affordable new standard for many high-volume applications.

Wellness is an important aspect of life and the places with the highest focus on wellness are hospitals or healthcare facilities. When they’re not delving into how high and unhealthy CO2 Effects on their patients, wellness providers from hospitals to clinics to treatment centers and researchers in these fields should review the findings of researchers (some from over 20 years ago) on how unhealthy CO is2 Levels generally affect healthy individuals.

As part of their treatment, hospitals and healthcare facilities of all types should consider the next step in their treatments and healthcare protocols to ensure the environment is most conducive to their patients’ recovery. An acceptable CO2 level also enables optimal cognitive processes for healthcare providers. Because patients are not at their normal level of fighting infection, they don’t need extra stress on their bodies from unhealthy air, and faster recovery could result from a healthier environment. This is true even for patients recovering at home.

implement CO2 Monitoring at critical points

Infineon has taken a leadership role at its Munich headquarters and installed CO2 Sensors in every conference room. The CO2 Concentration measurements are effectively a people counting technique. The readings indicate whether too many people are present in the confined space for the capacities of the circulation and filter system.

figure 2 Meeting rooms are equipped with CO2 Monitoring boxes to control air quality and reduce the risk of transmission of COVID and other airborne viruses. Source: Infineon

Appropriate actions can be taken with this data, including something as simple as opening a window (figure 3). Ultimately, a sophisticated system design with CO2 Sensors could automatically take a variety of actions to improve the situation and avoid problems for participants. Even a simple red/green light detection system can alert meeting organizers and attendees to take appropriate action to avoid a health hazard.

figure 3 XENSIV PAS CO2 The uncompensated reading is consistent with the reference meter used to monitor meeting room CO2 level in Munich. Source: Infineon

While meeting attendees have long used their own internal perceptions — with each person responding with their own individual response mechanism — to determine when a crowded space is becoming unhealthy, or stuffy as it’s commonly called, is a CO’s unbiased input2 The sensor can alert all participants to the need to respond appropriately before people in the room experience discomfort and reduced performance. Ultimately, this type of proactive response in smart homes and smart buildings would eventually become a feature that differentiates an advanced system from the average heating, ventilation, and air conditioning (HVAC) system that controls air not only based on temperature, but also other environmental factors, including CO2.

As a sponsor of the Munich Security Conference, Infineon CO2 Conference monitoring with red/green light levels in rooms. There were no red lights at this particular event, so no action was required. However, the next event could be completely different as everyone’s circumstances change.

Let’s clean the air

With a proactive approach to adding CO2 Measurements at a facility can enable industry leaders, particularly healthcare facilities, to realize many proven benefits before regulations come into force. Infineon takes proactivity very seriously and has taken the first step in its own facility and encourages other stakeholders to take the first step in improving air quality in their facilities – before it is necessary. Certainly, those who can expect CA Title 24-like requirements to spread across the United States or other region-specific requirements to be implemented around the world should be among the first to add CO2 measurements on their control system and take their own first step towards cleaner, healthier air.

Dal Frond is Marketing Manager for MEMS sensors at Infineon Technologies.

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