Ozone limit values ​​in the exhaust air from commercial canteen kitchens

When using UV tubes in commercial kitchen exhaust air, UV radiation generates ozone, which can be used to oxidize and reduce odorants in the exhaust air. The same approach is followed when using so-called ozone generators. Regardless of the system used, however, it should be noted that there are ozone limit values ​​to be observed!

UV tubes in a kitchen capture hood
UV tubes in a kitchen capture hood

Indoor ozone limits

In many countries in Europe and Amerika, the limit for indoor areas for ozone is still set to a maximum of 2 mg ozone per one cubic meter of indoor air (ozone limit of 2mg/m3). In Germany that was the previous ozone limit, which has been lifted, however, in Switzerland, for example, this limit still exists. You can find information on:

https://de.wikipedia.org/wiki/Ozon in the upper area on the far right, where the safety instructions are noted in the color-coded box.

The German DFG played a leading role in lifting the previous ozone limit in Germany: according to the classification criteria for carcinogenic substances according to the German Research Foundation (DFG), ozone is classified in Category IIIB “insufficiently examined, but with cause for concern”.

Outdoor ozone limits

For the ozone limit value in the outdoor area, even in the comments of German kitchen ventilation experts, limit values ​​for the kitchen exhaust air of 20 mg/m3 are mentioned. For example, you can read the following on the cci page under the comments https://cci-dialog.de/:

“Complaints about excessive ozone concentrations in the exhaust air can occur, even if the ozone concentrations released are far below the permissible limit of 20 mg/m³.”

On the side of the German Federal Environment Agency, however, the following is noted:

“In order to rule out health risks for the population in the event of short-term exposure to increased ozone concentrations, the 39th BImSchV sets information and alarm threshold values. The information threshold of 180 micrograms per cubic meter (µg/m³), ​​averaged over an hour, serves to protect the health of particularly sensitive population groups. The alarm threshold of 240 µg/m³, averaged over an hour, describes the threshold, if exceeded, there is a risk to the health of the entire population.

The following can also be found on the website of the Deutsches Ärzteblatt:

“An EU directive provides 180 µg/m3 (1-hour value) as an information threshold and 240 µg/m3 as a warning threshold for the population. Changes in the lung function parameters already occur at values ​​between 160 µg/m3 and 240 µg/m3.”

Please note that the units of the last noted limit and threshold values ​​are units, in micrograms per cubic meter (µg/m3)! That the above-mentioned value of the quoted kitchen ventilation experts of 20mg/m3, would be a value of 20,000µg/m3 in this unit of measurement!!!!

In this comparison, it is now self-explanatory why an ozone limit value for indoor spaces of 2mg/m3 = 2,000µg/m3 is an ozone limit value, which ventilation experts, who only work reasonably seriously, may no longer strive for! The same applies in exactly the same form, one to one, for outdoor use and, consequently, also for the exhaust air from commercial kitchens.

You can find a summary of this on, for example: https://www.allum.de/stoffe-und-ausloeser/ozon/grenzwerte-richtwerte

This fact about the ozone limit values ​​must simply be observed without any ifs and buts, when using UV systems and ozone generators, to reduce odor nuisance and there must also be no technical evidence that these thresholds are not exceeded.