Indoor air quality testing at #HealthyBuildings18

ASBP Patron member PPM Technology carried out air quality testing during the day at our Healthy Buildings Conference and Expo at UCL, 14th February 2018.

A sensor was installed in both the exhibition space and the lecture theatre with CO2, TVOCs (total volatile organic compounds), temperature and relative humidity being measured.

CO2 measurements

CO2 levels were measured in the main exhibition space in which delegate registration took place in the morning and refreshments were served at intervals throughout the day. CO2 levels were also measured in the principal lecture theatre, which was occupied by up to 150 delegates.

The results were as expected with high measurements in the exhibition space when occupancy levels were high and low measurements in the lecture theatre when occupancy was low, and vice versa.

CO2 levels peaked at around 900 ppm which is typical of occupied indoor spaces with reasonable air exchange rates. CO2 levels of between 1000-2000 ppm are when complaints of drowsiness and poor air quality are commonly recorded, whereas levels of 2000+ ppm can result in air likely becoming stuffy and stagnant and lead to more severe symptoms such as headaches, increased heart rate and nausea.

Total volatile organic compounds

Total VOCs were measured in the exhibition space only. The results are both interesting and concerning as it shows that TVOC measurements steadily decline throughout the day and are not influenced by increases in occupancy levels, and therefore do not follow the same pattern as the CO2 measurements.

CO2 measurements are often used as a proxy for indoor air quality and these results show that measuring CO2 levels alone do not show the full picture in terms of the quality of the indoor environment.

TVOC measurements peak extremely high early in the morning and stay at higher than usual levels until the afternoon. It is thought that is likely due to a particular cleaning product being used early in the morning, which has a very high VOC count.  We have suggested that we should conduct a repeat test to investigate these issues further.

Temperature and relative humidity

The results of the temperature and relative humidity measurements are as expected with some slightly higher temperatures in the main lecture theatre at around midday when it is fully occupied.

About PPM Technology

PPM Technology is based in Caernarfon, Wales, UK, where we have a custom built development and production facility on the Cibyn Industrial Estate. With dedicated teams in Production, Management and R&D we aim to provide fast and friendly service backed with the experience of a long history in the sector.

PPM Technology is an established manufacturer and supplier of portable and fixed gas detection instruments based on electrochemical sensing technology. PPM instruments monitor levels of hazardous compounds in air such as formaldehyde and other toxic gases.

To find out more, visit

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