Air quality in interpretation booths – Study – Chambre Belge de Traducteurs et Interprètes

1. Interpreting in Times of COVID

March 2020. The reality of conference interpreting changed overnight: instead of sharing a traditional interpreting booth, interpreters had to adapt and work in separate booths, in a hub or from home. A few months ago, the BKVT/CBTI Interpreters’ Committee examined the legislation on safe working conditions and updated the previously issued COVID recommendation. Meanwhile, as we start 2022, the topic of air quality has never been more relevant. So, it is time to explore this subject more in-depth.

2. What Do We Know?

Recent scientific research shows that aerosols are the main source of COVID contamination. As we breathe, but even more so when using our voices and/or exercising more strenuously, aerosols are released which may contain bacteria and viruses. Since we also breathe out CO2 at the same time, the CO2 concentration is often used as an indicator of the ventilation rate in rooms where people are present. The standard for air quality is 900 ppm of CO2. If this value is exceeded, measures must be taken to improve air quality. From 1200 ppm onwards, air quality is considered to be downright poor.
Good to know: because face masks stop aerosols but not CO2, they are a good way to stop the spread of aerosols, even at higher CO2 concentrations.

3. Ventilating the Booth

To ensure good air quality, it is important to ventilate regularly. This way, the indoor air is refreshed and potentially virus-carrying aerosols are removed.

Unlike employees who have a fixed workplace, conference interpreters work in a different environment every day. It is therefore not possible to have sufficiently reliable data for each workplace (e.g. on the available ventilation). Moreover, there are a lot of factors which are completely beyond the interpreter’s control (quality of the outside air or of the air in the room where the mobile interpreting booth is placed, position of the booth, organisation of natural ventilation moments/breaks, etc.)

4. To Measure Is to Know

A CO2 measurement can be a first step in better understanding the situation. Of course, the use of a CO2 meter has no impact on air quality. This requires human or mechanical intervention: opening of windows/doors, providing a well-functioning ventilation system, air purification.

During the last week before the Christmas holidays, some colleagues organised a number of CO2 tests in fixed and mobile booths, with the door closed and with 2 interpreters each wearing a face mask for their own safety. In all cases, the 900 ppm limit was reached after only 2 to 3 minutes. The use of the ventilation provided in the latest generation of mobile booths had only a very limited influence. It should be noted, however, that the recommendation to place the CO2 meter at least one and a half metres from the people present was difficult to achieve due to the limited space in an interpreter’s booth.

As soon as the 900 ppm level was reached, the booth door was opened. The surrounding area was continuously well ventilated (open window) and there were only a few people present. When the door was opened, CO2 levels in the air dropped fairly quickly (after 10 to 15 minutes) to an acceptable level (close to the concentration in the ambient air at the start of measurement). From this we can conclude that in any case it is safer to interpret with the door open, at least if the ambient air that provides the ventilation is of good quality…

5. Air Purification as an Alternative

Ventilating with outside air is the best way to bring fresh air into the booth. As this is not always possible, we have also examined the possibility of purifying the air in the booth.

The government has published a list of some 300 air purification systems that have been tested and approved. Most of them were designed for larger spaces and are therefore rather bulky and heavy, and they are quite expensive, but there are also some more compact devices on the list. An additional requirement for use in an interpreting booth is the noise level produced by such equipment, as the humming of such a device may be audible to the audience and/or may disturb the interpreters’ concentration levels.

We contacted some 15 manufacturers and suppliers of air purification systems. In the end, two companies were willing to make a device available for our tests. These were the Radic8 Hextio and the AirProtecting 50 appliances. These air purification systems each have their own technology, which neutralises bacteria, viruses (including the corona virus), moulds, etc. Most of them use a combination of filters (active carbon, HEPA or dust filters) and UVC light, but ionisation and photocatalysis can also be part of the process.

Of course, we do not have the scientific knowledge or equipment to effectively measure air quality, but an employee of the Medtradex company demonstrated with a particle meter that the dust particles were purified from the air when using the Radic8 Hextio. When the CO2 meter reached 900 ppm, the counter for particles with a diameter of up to 0.5 μm stood at 10,051. After the unit had been working for 30 minutes, the level was reduced to 7,579, which was lower than the measurement outside the booth at the start of the test. Remarkably, the CO2 meter at that time exceeded 2,000 ppm. This is because these air purifiers do not affect CO2 levels: to reduce these, ventilation remains the only solution.

As a second step, we tested the noise level of the two units, first in a hub setting with a Blue Yeti microphone, then in professional booths with Bosch and Televic interpreter consoles. While the Blue Yeti did not pick up the sound, the microphones in the interpreters’ booths proved too sensitive to the Radic8 Hextio, which produced a ventilation noise in the headsets, especially for the Televic interpreting console. With its 20 dB, the AirProtecting 50 unit was not detected.

We can conclude from these tests that air purification in an interpreter booth can certainly contribute to a healthy working environment, as air purification systems neutralise all kinds of micro-organisms, including the COVID virus. However, it is still important to ventilate in order to reduce CO2 levels: too high a concentration of CO2 can also cause headaches, fatigue and concentration problems. In many settings, it is unfortunately not possible to draw on fresh (outside) air directly, and ‘second-hand’ air from the room where the event takes place, usually involving a large number of people, is often used for ‘ventilation’. Furthermore, it is not always and everywhere possible to work with an open door.
Air purifying systems cannot replace other measures: keeping a distance, face masks, hand hygiene and ventilation remain important. But air purification can contribute significantly to a healthy work environment. Tip: make sure that the device does not produce too much noise.

Thanks to Olivier from Medtradex, Peter from DCPTechnics and the teams from Duvall and Eloquentia.

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Air quality in interpretation booths – Study