Indoor Air Quality
Know your indoor air quality to improve your health and productivity
When we think of "air quality", we tend to think of air pollution in the regions surrounding our homes. We rely on measures such as the Air Quality Index to let us know when airborne pollutants in our towns or cities reach levels that may cause or exacerbate health issues. When summer humidity brings an increased risk for asthma sufferers or when dangerous smog accumulates in cities, the message is simple: to protect your health, stay indoors.
However, some of the most polluted air we breathe is found indoors. From dust to formaldehyde to radon, unseen elements and particulate matter inside our homes and offices can cause both short- and long-term health issues. Given that people spend about 90% of their time indoors, measuring and controlling indoor air quality should be a top priority.
A growing body of research points to a link between COVID-19 cases and low humidity and/or high levels of pollution. Furthermore, high CO2 concentrations relate to virus infections.The higher the proportion of CO2 particles, the higher the proportion of air that was breathed several times. And thus the risk of inhaling aerosols that another person in the same room has breathed out shortly before. The CO2 concentration is therefore a kind of indirect measurement for possible exposure to viral aerosols.
Being able to control and monitor these variables is therefore more important than ever.
Important Indoor Air Quality Indicators

Carbon Dioxide
CO2 is part of the human metabolism. It is produced when, for example, carbohydrates are metabolized to generate energy. The produced CO2 is then transported out of the body by respiration. The CO2 concentration in the inhaled air is decisive for the metabolism. Depending on the level of the concentration in the air breathed in, various symptoms can occur that affect daily life and health. High CO2 concentrations in the air we breathe lead to concentration problems and fatigue. The performance potential of people in the room decreases constantly the higher the amount of CO2 in the air gets. Furthermore, CO2 concentrations relate to the potential of virus infections.
The level of CO2 in the air can be thought of as a "traffic light" system: Green is between 400–1'000 ppm; yellow is between 1'000–1'600 ppm and is where 80% of people are satisfied with perceived air quality; red is ≥1'600 ppm and is where there are detectable negative impacts on human health and well-being. At this level, the air quality is considered poor and the risk of viral transmission is increased.

Humidity and Temperature
Do you find it hard to breathe in your home some days? Are you more prone to headaches and asthma attacks during the summer months? You’re not allergic to heat - but you may have serious humidity problems in your home or office. When we talk about indoor air quality, humidity is one of the main things we’re referring to. Too high or too low humidity levels in closed spaces can lead to various issues. For example, bacteria and viruses that cause respiratory infections thrive in extremely high and extremely low humidity. Mold spores, dust mites and other allergens survive best in high humidity environments. Furthermore, higher humidity can increase the levels of noxious chemicals in the air, which may include ozone and formaldehyde.
40-60 % relative humidity is an optimal level for the immune system and our respiratory system. It reduces the spread of seasonal respiratory diseases and increases well-being.

Volatile Organic Compounds (VOCs)
VOCs originate from a number of different possible sources, like building materials, tobacco smoke, people and their activities, and indoor chemical reactions. Exceptionally high VOC levels are typically found in new buildings or after renovation. Further, when using products that contain VOCs, such as air fresheners or cleaning agents, people expose themselves and others to high pollutant levels that can persist long after the activity has finished. A number of systematic human exposure studies have shown various adverse health
effects caused by exposure to elevated VOC levels. Among the effects reported by participants are dryness and irritation of the eye, the nose and the throat, headaches, and dizziness.
Sensirion’s powerful VOC Algorithm analyzes VOC events detected by the SGP40 sensor and maps them to a VOC Index. This VOC Index provides a practical quantification of VOC events relative to each individual sensor’s typical indoor environment. In this way, it behaves similarly to the human nose, which is highly susceptible to changes in odor, but it also detects VOC events that are not perceived by humans. The VOC Index indicates to what extent the indoor air quality has deteriorated or improved compared to the sensor’s typical VOC environment. Learn more about the VOC index at www.sensirion.com/sgp40.

Particulate Matter (PM2.5)
Particulate Matter (PM) is a complex mixture of solids and aerosols composed of small droplets of liquid, dry solid fragments, and solid cores with liquid coatings. Particles are defined by their diameter for air quality regulatory purposes. Those with a diameter of 10 microns or less (PM10) are inhalable into the lungs and can induce adverse health effects. A number of adverse health impacts have been associated with exposure to PM2.5. Short-term exposures (up to 24-hours duration) have been associated with premature mortality, increased hospital admissions for heart or lung causes, acute and chronic bronchitis, asthma attacks, emergency room visits, respiratory symptoms, and restricted activity days.
Indoor PM levels are dependent on several factors including outdoor levels, infiltration, types of ventilation and filtration systems used, indoor sources, and personal activities of occupants. In homes without smoking or other strong particle sources, indoor PM would be expected to be the same as, or lower than, outdoor levels. To know what the limits of PM exposure are, please consider official air quality standards. The US Environmental Protection Agency defines the AQI levels as follows: With regard to primary (health-based) standards for fine particles (generally referring to particles less than or equal to 2.5 micrometers (mm) in diameter, PM2.5), the EPA is revising the annual PM2.5 standard by lowering the level to 12.0 micrograms per cubic meter (mg/m3) so as to provide increased protection against health effects associated with long- and short-term exposures (including premature mortality, increased hospital admissions and emergency department visits, and development of chronic respiratory disease), and to retain the 24-hour PM2.5 standard at a level of 35 mg/m3.
How can you improve your indoor air quality?
To improve your indoor air quality, it is important to know about your air quality conditions. That's where Sensirion steps in. With our market leading environmental sensor solutions, we enable precise and accurate monitoring of these air quality indicators. By having a smart ventilation system / routine or by using air treatment devices such as air purifiers or air conditioners with fresh air exchange, you can improve your air quality, increase your health and minimize the risk of virus infections.
Carbon Dioxide Sensors

CMOSens® Technology for IR detection enables highly accurate carbon dioxide measurement at a competitive price. The small module height allows easy integration into different applications.
Sensirion is the world’s leading manufacturer of digital relative humidity sensors. Best-in-class products, unmatched experience, and excellent application support make Sensirion the no. 1 partner for humidity sensing.
SGP40 is Sensirion’s new digital VOC (volatile organic compounds) sensor designed for easy integration into air treatment devices and air quality monitors. In combination with Sensirion’s powerful VOC Algorithm, the sensor signal can be directly used to evaluate indoor air quality, e.g., for triggering the gradual fan control of an air treatment device.
The SPS30 PM2.5 sensor isbased on laser scattering and makes use of Sensirion's innovative contamination-resistance technology. This technology, together with high-quality and long-lasting components, enables precise measurements from the device's first operation and throughout its lifetime of more than ten years.
Related Topics
Petition "40to60RH"

It has been proven that indoor humidity plays an important role in preventing virus transmission and improving the response of the immune system. Extensive research shows that a relative humidity (RH) between 40% and 60% is optimal to minimise the spread of viruses such as influenza. Scientists are therefore calling on the WHO to revise the global guidelines for indoor air quality.
The importance of indoor humitidy is crucial to us. As market leader in humidity sensing it is important to us to support petition 40to60RH. Improving people's health is part of our mission and therefore we encourage everyone to support this petition to gain the attention of the World Health Organization.
Support the petition and learn more about it: www.40to60rh.com

Reduce the risk of virus infection in classrooms
Ventilate indoor spaces regularly and thoroughly - this is recommended by the Federal Environment Agency to reduce the risk of Sars CoV-2 infection. This announcement is particularly relevant in view of the fact that the school has started again at full class size. For this reason, the supply of fresh air in the classrooms should also be as high as possible, regardless of other protective measures such as keeping minimum distances or wearing a mouth-and-nose cover. After all, droplets and tiny aerosol particles should play a decisive role in the transmission of Sars-CoV-2. Especially the aerosol particles that are produced when breathing, coughing, speaking and sneezing can float in the air for hours or days, according to current knowledge. Consistent ventilation can significantly reduce the risk of infection, but cannot provide 100% protection.
Do you work in one of these areas?

Hospital & Medical Institutions
Do you want to reduce the risk of infection with respiratory diseases caused by aerosols due to high patient and visitor fluctuation?

Offices
Do you feel responsible for your employees, do you attach great importance to occupational health and safety and do you also take the indoor air quality into account?

Restaurants, Clubs and Leisure Centers
Do you want to offer your customers and visitors comfort, safety and well-being and display this visibly?

Schools and Educational Institutions
Are you interested in a healthy indoor climate for children, Students, educators and employees who spend time together indoors in large numbers?