Dr. Christian Meyer
Product Marketing Manager
Published: August 8, 2018

Improving clean air levels is becoming more important these days, especially in heavily polluted areas. People are turning to indoor air monitors, purifiers and filters to decrease the amount of polluted air they are breathing. There are several reasons why room hygiene is an important factor for our well-being. In addition to serious health concerns, there is the psychological aspect – homes, offices, and other environments that smell clean typically seem more welcoming than areas with foul or unpleasant odors.

No Universal Definition for Clean Air

Currently, there is no global standard that defines good air in the context of indoor air quality (IAQ). Some countries have local approaches and published studies that give indicators of clean ambient air and its implications. All of these studies show that is a direct link between the total volatile organic compounds (TVOC) and poor IAQ. Some of these publications also include some non-VOC related IAQ parameters, such as radon, mercury, bacteria, and others, which are only relevant for the particular organization’s mission.

A definition of clean air should not be mistaken with maximum allowable concentrations (workplace threshold limit value), which are usually valid for exposures during an 8 hour/5 day-a-week situation in a work environment. TVOC concentration limits for indoor air quality are typically much lower because people spend more time at home than at work.

Typical Source of TVOC Inside a Home


Insights on Clean Air From the UBA Study

The “Umweltbundesamt” (UBA) is the German Environment Agency, which carried out investigations and studies on indoor air and the TVOC for several years. A 2007 study from the organization became very well-known internationally. It is a compendium of 48 other research papers and reports that seek to understand and summarize the best knowledge on indoor air quality. In particular, the TVOC references for indoor air quality are useful because not only does it identify levels of potential hazards, but it also provides guidance on which actions are recommended based on these TVOC levels. This 5-step TVOC indication for IAQ is used by Renesas’ ZMOD4410 gas sensors (below).

Levels of Clean Air According to the German Environment Agency


When choosing an IAQ sensor, look for test data that supports a definition of clean air, such as the UBA. Many companies define their own IAQ version of clean air, but without the research and testing carried out by a world-respected organization, consumers have little confidence in the data that they receive. The ZMOD4410 was tested by an independent research institute (“Kurt Schwabe Institute,” KSI) for sensor technology against the UBA study. As a result of the testing, the KSI certified that the ZMOD4410 exhibited excellent sensor behavior and was categorized as a state-of-the-art metal oxide (MOx) sensor.

Renesas has developed the ZMOD4410 gas sensor based on the UBA study and has translated the study from German into English for our international customers, which is now acknowledged and approved by the UBA.

Visit the UBA website and Renesas’ gas sensor page for more information.

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