Due to the current situation, the air quality in rooms where many people work at the same time(air quality in classrooms or meeting rooms) should be monitored especially now. In addition, the air quality can also have a negative impact on mental and physical performance. This can quickly lead to an atmosphere that reduces performance or even causes illness. Healthy air is also particularly important where important decisions are made. That's why we monitored and tested the air quality at a special client of ours, a court, over the course of a week.
The study had the following objectives:
- Record, document and evaluate air quality and pollutants such as particulates, nitrogen dioxide, carbon dioxide, chemicals / VOCs and aerosols over one week,
- Checking whether the current arrangements with regard to corona prevention are correct and sufficiently implemented,
- Derive proposals for the improvement of air quality
General experimental set-up for air quality measurement
A total of three air-Qs were installed in different rooms - in a staff office, where up to four staff members work at the same time, as well as in a small and a large courtroom, where hearings were also held during the week in each case.
Large-scale air purifiers were already installed in the courtrooms. The data from the air-Q air analysers also show what effect these had during the hearings with regard to aerosol and VOC pollution and whether additional ventilation was used to reduce carbon dioxide. Since the measured values and results in the two negotiation rooms are very similar, the small room is evaluated below as an example.
Evaluation of the measurements
In the court building, the air-Qs were operated without Wi-Fi access, as it was not possible to use the Wi-Fi available there for security reasons. The air-Qs were collected after the test and the data was then downloaded from the device. As a large amount of measurement data was involved, the data was not uploaded, but the SD card was simply removed and the data transferred to a table using our CSV converter, where it was analyzed in detail.
1. air quality in the staff office
In the staff office, the window was tilted and there was impact ventilation at regular intervals. This can be seen very nicely in the sawtooth pattern in the diagram. In addition, the increase in carbon dioxide between airing is not very strong and only amounts to a maximum of 850 ppm. With an unopened window, this value would already be reached after a short time.
2. courtroom
In the small hearing room, the times of court hearings are clearly visible - there were two sessions between which there was extensive ventilation after the carbon dioxide level reached a level of 1,600 ppm - from 9 am and from 12:45 pm. Within the second session from 1pm, the VOC level increased significantly more than in the first session from 9am. This can have different causes, e.g.:
- there was a stronger source of VOCs within the second trial in the room (more people, stronger perfumes, type of lunch)
- the VOC value was reduced within the first negotiation by an activated air purifier
While the window was closed shortly before the first session at 9 a.m. (recognisable from the sharply rising CO₂ value from 9 a.m. onwards), the particulates value(PM₂,₅) dropped very quickly to "0" µg/m³ from 9 a.m. onwards. Unfortunately, no record was kept in the hearing room about the use of the air purifier located there. However, the course of the readings indicates the use of the air purifier - without the air purifier, the particulate matter reading would have remained high for a long time, only dropping slowly and possibly never reaching "0". (See also our test of the Dyson air purifier).
Comparison with the second session: After the end of the first hearing from about 11:30 a.m. onwards, the particulates reading rose again because the window was opened (again recognisable from the sharply falling CO₂ value). From 12:45 p.m., the CO₂ value rose rapidly again due to the meeting participants - the window was now closed again. This time, however, the particulates reading (PM₂,₅) remained consistently high (albeit at a low level of only 2 µg/m³). With active air purifiers, the value would have dropped back to "0" very quickly. At the same time, the VOC value rose sharply to 1,600 ppb - much more than comparatively in the first trial. Both factors together (constant particulates value and very high VOC value) indicate that the existing air purifier was deactivated during the second trial.
Conclusion - ventilation behaviour and air purifiers work
Strict anti-COVID-19 rules are followed in the court. There is regular ventilation in the workrooms and the window is even tilted at least all the time. Thus, the risk of COVID-19 infection can be significantly reduced according to current knowledge.
In the hearing rooms, it is not possible to keep the window open all the time. Likewise, opening them during the session is not practical. For this reason, large-capacity air cleaners were installed. These do their job as hoped, are sufficiently large in size and can circulate the air in the room sufficiently to reduce aerosols and thus potential viruses in the air during the proceedings. However, care should be taken to ensure that the air purifiers are actually activated for each negotiation. After the negotiations, the room is thoroughly ventilated, which counteracts potential virus contamination as well as generally poor air quality and reduced concentration.
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