iiinova — where your digital self keeps evolving

Aurel Wünsch @aurel.indoorco2map.com · 28/09/2026

It’s been quite a while since I posted about indoorco2map.com here, but I’ve not been sleeping. 1) new website properly explaining the project will be put online on october 9th 2) a report going in depth into the data collected so far will also be released on the same day (one chart as teaser here)

Chart titled "The worst tenth of visits: over 2,500 ppm in pubs and bars". Horizontal box plots of indoor CO₂ for 19 types of places, from IndoorCO2Map open data (export of 23 September 2026, all countries, place types with at least 60 measured places). Each box shows the middle half of visits, a line marks the median, whiskers run from the 10th to the 90th percentile and a dot marks the 95th percentile. Percentiles are location-weighted: every place counts the same, however often it was measured. Dashed lines mark 1,200 and 2,000 ppm.

90th percentile (one visit in ten is higher), from highest to lowest: pubs 2,720 ppm, bars 2,551, places of worship 1,643, schools 1,571, theatres 1,533, doctors' practices 1,513, restaurants 1,399, supermarkets 1,394, cafés 1,382, cinemas 1,378, hotels 1,234, bakeries 1,177, hospitals 1,159, museums 1,109, drugstores 1,099, clothes shops 1,011, shopping centres 967, fast food 918, DIY stores 723. The six types from pubs to doctors' practices are shown in red because their 90th percentile is 1,500 ppm or more.

Pubs and bars have by far the longest tails: their boxes reach about 1,500 to 1,600 ppm and their 95th percentiles lie near 3,900 and 3,600 ppm. The other boxes lie roughly between 550 and 1,250 ppm.

Notes next to the chart: in pubs and bars the worst tenth of visits is above 2,700 and 2,550 ppm, the worst twentieth above 3,600. In doctors' practices one visit in ten is above 1,500 ppm, one in twenty above 1,800. School measurements are probably biased: they are mostly taken by teachers who control the windows and are more aware of air quality than the average teacher.

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Aurel Wünsch @aurel.indoorco2map.com · 04/09/2026

Im Hochadel war das mal sehr in Mode. Da kam es vor das man statt den 32 Vorfahren wenn man 5 Generationen zurückgeht dann halt nur 10 oder so hatte. (Ich vermute fast in 5. Generation ist es gar nicht so unüblich dass man nicht auf die vollen 32 kommt).

Ahnenbaum von König Karl II. aus Spanien. Statt der eigentlich erwartbaren 32 verschiedenen Vorfahren wenn man 5 Generationen zurückgeht sind es nur rund 10. (bin etwas überfordert von dem Ahnenbaum.

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Aurel Wünsch @aurel.indoorco2map.com · 30/08/2026

Irgendwie hab ich manchmal etwas Zweifel an diesen Produktivitätsgewinnen durch KI...

Screenshot with following text: **Currently, our team is working hard to answer tickets received around mid May.** We sincerely appreciate your patience as we work diligently to get to your request.

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Aurel Wünsch @aurel.indoorco2map.com · 26/08/2026

Wie gesagt, die ASR 3.5. hat eine völlig andere Formulierung bezüglich Mindesttemperaturen als bei den zu hohen Temperaturen. Und es wird einfach kulturell / institutionell völlig anders gehandhabt weil kaputte Heizungen / zu kalt historisch immer schon ein Problem war - die übermäßige Hitze nicht.

Auszug aus der ASR 3.5. : 4.2 Lufttemperaturen in Räumen
(1) In Arbeitsräumen muss die Lufttemperatur in Abhängigkeit von der Arbeits-schwere und Körperhaltung mindestens den Werten in Tabelle 1 entsprechen, wobei diese Lufttemperatur während der gesamten Nutzungsdauer zu gewährleisten ist.

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Aurel Wünsch @aurel.indoorco2map.com · 26/08/2026

km.baden-wuerttemberg.de/de/schule/al... Werde das jetzt nicht für alle 16 Bundesländer raussuchen, hier als Beispiel, gibt sicher paar Unterschiede. Und ja ist nicht Bundesaufgabe, Merz spricht ja auch nicht vom Bund sondern vom Staat, aber der Bund kann die ASR ändern und verpflichtender machen.

1. Welche Raumtemperaturen sind in Unterrichts- und Betreuungsräumen einzuhalten?
Vorgaben für die Raumtemperatur in Klassen- und Betreuungsräumen ergeben sich grundsätzlich aus der Arbeitsstättenverordnung und aus Vorgaben der gesetzlichen Unfallversicherung. Diese Regelungen sehen aktuell eine Temperatur von 20 Grad Celsius bei leichten sitzenden Tätigkeiten als ausreichend an. Das gilt sowohl für Schulen als auch für Kindertageseinrichtungen. Die Raumtemperatur kann zum Beispiel beim Lüften allerdings auch unterschritten werden. Hier können alternative Maßnahmen, wie das Tragen wärmerer Kleidung ergriffen werden.

Die jeweiligen Vorschriften finden Sie hier:

Arbeitsstättenverordnung: BMAS - Arbeitsstättenverordnung
Technische Regeln für Arbeitsstätten: https://www.baua.de/DE/Angebote/Regelwerk/ASR/ASR-A3-5.html

Regeln der gesetzlichen Unfallversicherung:
Schule - https://publikationen.dguv.de/widgets/pdf/download/article/3581
Kita - https://publikationen.dguv.de/widgets/pdf/download/article/3604

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Aurel Wünsch @aurel.indoorco2map.com · 24/08/2026

Some might be close to retirement by now ;)

Screenshot of Sopwith the 1984 Videogame

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Aurel Wünsch @aurel.indoorco2map.com · 19/08/2026

Inzwischen zieht es bis fast Kassel und noch etwas östlicher. Auch dort noch über dem 24-Stunden Guideline level der WHO. In Aachen zur Zeit fast das 30-fache dessen was das WHO-Ziel zum Jahresdurchschnitt ist. An einem Tag also fast die Exposition die man in einem Monat haben sollte.

Screenshot von Windy.com mit dem PM2.5 layer. Bei Aachen werden 144 microgramm/m³ angezeigt. Die Erhöhte Konzentration zieht sich, graduell abnehmend in einem geschätzt 50 km breitem Band bis östlich von Kassel- dort noch etwa 25 microgramm/m³

Tabelle aus den WHO global air quality guidelines. für PM2.5 wird ein Air Quality Guideline level von 5 µg/m³ angegeben als Jahresdurchschnitt und 15 µg/m³ für eine 24-stündige Exposition.

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Aurel Wünsch @aurel.indoorco2map.com · 15/08/2026

Vor dem Hintergrund vielleicht noch interessant wie die Internationalen Anforderungen der OTIF sind, die soweit ich mich erinnere auch bei uns in die Nationalen Richtlinien übernommen worden sind.

Der Ausschnitt stammt aus der OTIF-Vorschrift UTP LOC&PAS (Lokomotiven und Reisezugwagen), Entwurfsfassung vom 11.08.2025, Seite 75. Rot umrandet ist Abschnitt 4.2.5.8 zur Luftqualität im Innenraum. Er verlangt, dass Menge und Qualität der Luft in den von Fahrgästen und Personal genutzten Bereichen kein zusätzliches Gesundheitsrisiko gegenüber der Außenluft erzeugen, und dass eine Lüftungsanlage im Betrieb ein akzeptables CO2-Niveau hält. Als Grenzwert nennt der Text 5000 ppm, mit zwei Ausnahmen: bei Ausfall der Lüftung durch Strom- oder Anlagenausfall, wobei eine Notversorgung mit Außenluft greifen muss und bei batteriegestützter Zwangslüftung mindestens 30 Minuten unter 10000 ppm gehalten werden müssen, sowie beim gezielten Abschalten der Außenluftzufuhr, um Fahrgäste vor Rauch und Abgasen zu schützen, etwa in Tunneln oder im Brandfall. Darüber steht noch der Rest von 4.2.5.7 zu Übergangstüren.

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Aurel Wünsch @aurel.indoorco2map.com · 15/08/2026

So hoch ist eher selten, zumindest als Durchschnittswert, das wäre unter den schlechtesten 2%. Wenn man nicht auf den Durchschnitt schaut sondern auf die Maximalwerte sieht man oft aber auch noch deutlich höhere, hier mal noch ein Beispiel. Lüftung kann auch auf (teilweise) Umluft gestellt sein.

Flächendiagramm mit dem Titel "Durchschnittswert CO2 in ppm von 301 ICE Messungen, sortiert nach CO2". Jede Messung ist ein Punkt auf der x-Achse, aufsteigend nach ihrem CO2-Durchschnitt geordnet, die y-Achse reicht von 0 bis 2800 ppm. Die niedrigsten Messungen liegen bei etwa 550 ppm, danach steigt die Kurve lange gleichmäßig an. Ungefähr ab Messung 110 liegen die Werte über 1000 ppm, also bei fast zwei Dritteln aller Messungen. Ganz rechts bei etwa 1400ppm wird die Kurve steil und nur wenige Messungen liegen darüber, die höchsten Messungen erreichen rund 2600 ppm.

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Aurel Wünsch @aurel.indoorco2map.com · 01/08/2026

Despite the current low-activity, the project activity is pleasantly stable still at around 30 daily Building measurements and 10 daily transit measurements. With the forthcoming social media activities the hope is to increase that a lot.

Chart showing the activity levels over time - for buildings only. For most of the project duration it has been at around 30 per day i naverage, but over time the share of germany decreased from 80% to 33%. The userbase expanded to more countries but activity per user usually declines over time (the app is anonymous but this general trend can still be extrapolated from the data).

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Aurel Wünsch @aurel.indoorco2map.com · 01/08/2026

While the website is not finished yet, there is a 2-Page Introduction PDF which explains the core idea behind the project. indoorco2map.com/introduction...

First page of the linked PDF. As the complete text on it is too long to past here the following is just the Introductory paragraph: IndoorCO2map.com is a global citizen science project that maps air quality in public indoor spaces.
The open-source app requires no user registration and can be used by anyone with a CO2 monitor.
Together, contributors worldwide are building a publicly accessible record of indoor air quality at a larger scale than any existing centralised dataset. The project aims to make indoor air quality visible, empower people to make informed choices, and support evidence-based health policy over the long term.
The remainder of the text can be read in the PDF

Second page of the linked PDF. As the complete text on it is too long to past here the following is just the final paragraph: The air we share is one of the biggest environmental factors in our daily health, and one of the most neglected—but it doesn’t have to stay this way. The IndoorCO2map community advances the movement for clean indoor air, one measurement at a time.
The remainder of the text can be read in the PDF

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Aurel Wünsch @aurel.indoorco2map.com · 28/07/2026

healthcare-in-europe.com/en/news/jet-... das hier zum Beispiel.

Image showing different amount of bacteria in the air after using different hand drying methods, the most for "Jet Air Dryers" , medium amount for "Warm Air Dryers" and least when using Paper Towels.

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Aurel Wünsch @aurel.indoorco2map.com · 23/07/2026

Thanks for the info - which is a bit strange that this happened, as it is set to englisch now without me changing anything. Will keep an eye on it.

screenshot of the new Post screen of myself which shows its set to english

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Aurel Wünsch @aurel.indoorco2map.com · 05/07/2026

Ja wird es bislang nicht, aber das hat ja keine technischen Gründe sondern eher kulturelle, ästhetische und regulatorische Gründe. Wenn das in Skandinavien eine der Standardlösungen ist spricht hier wenig dagegen.

Diagramm, dass die Wärmepumpenverkäuft in Norwegen, Finland und Schweden zeigt. Über 75% der verkauften Anlagen in den Letzten Jahren sind Luft-Luft-Wärmepumpen

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Aurel Wünsch @aurel.indoorco2map.com · 05/07/2026

Luft-Luft-WP kühlen schon gut und Teil des Problems ist dass die immer außen vor sind wenn es um Wärmepumpen geht... gerade für Wohnungen in MFH ist das eine Lösung die man viel mehr pushen könnte. Das Bild sollte das Zielbild sein. Da muss man sich halt davon lösen was ästhetische Gewohnheit ist.

Image of a multi-appartement home with 3 stories x 5 windows visible and there is an AC or Air-to-Air-Heatpump in every one of them.

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Aurel Wünsch @aurel.indoorco2map.com · 02/07/2026

Arztpraxen gehören schon jetzt mit zu den Orten an denen die Luftqualität am schlechtesten ist und das Infektionsrisiko dadurch höher. Wenn da jetzt alle für ihre AU hinmüssen wird es noch ärger (und kurze AUs sind oft auch Atemwegsbedingt). Die Änderung wird zu mehr, nicht weniger Fehltagen führen

Stacked bar chart of indoor CO₂ distribution by GO IAQS air quality category. Bars show % of locations in each category per group, sorted best to worst. Data: 3.587 locations · 9.154 visits shown · 14 location types (most frequently measured). Filters: Germany; all location types; Apr 11, 2024–Jul 2, 2026. doityourself: Good 92.4%, Moderate 7.6%, Unhealthy 0.0%. clothes: Good 85.0%, Moderate 11.9%, Unhealthy 3.1%. fast_food: Good 82.6%, Moderate 15.1%, Unhealthy 2.3%. furniture: Good 82.4%, Moderate 17.6%, Unhealthy 0.0%. mall: Good 79.6%, Moderate 19.4%, Unhealthy 1.0%. pharmacy: Good 74.7%, Moderate 24.1%, Unhealthy 1.1%. museum: Good 72.5%, Moderate 20.9%, Unhealthy 6.6%. bakery: Good 70.1%, Moderate 27.8%, Unhealthy 2.1%. chemist: Good 58.2%, Moderate 38.4%, Unhealthy 3.4%. cinema: Good 55.8%, Moderate 32.6%, Unhealthy 11.6%. cafe: Good 54.6%, Moderate 31.9%, Unhealthy 13.5%. restaurant: Good 51.7%, Moderate 34.0%, Unhealthy 14.3%. doctors: Good 34.7%, Moderate 49.4%, Unhealthy 15.9%. supermarket: Good 31.0%, Moderate 57.3%, Unhealthy 11.7%.

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Aurel Wünsch @aurel.indoorco2map.com · 08/06/2026

Bibliotheken sind auch deshalb gute Ortezum lernen weil sie größtenteils gute Luftqualität haben (sample Size ist noch nicht die größte für die Kategorie aber die Bisherigen Messungen sind doch sehr ermutigend)

Histogram of indoor CO₂ distribution (location count per CO₂ bin, bin size: 200 ppm). Filters: Germany; Libraries; Apr 11, 2024–Jun 7, 2026. Data: 53 locations · 116 visits. 400–600 ppm: 14 locations; 600–800 ppm: 25 locations; 800–1000 ppm: 6 locations; 1000–1200 ppm: 4 locations; 1200–1400 ppm: 3 locations; 1400–1600 ppm: 0 locations; 1600–1800 ppm: 1 location; 1800–2000 ppm: 0 locations; 2000–2200 ppm: 0 locations; 2200–2400 ppm: 0 locations; 2400–2600 ppm: 0 locations; 2600–2800 ppm: 0 locations; 2800–3000 ppm: 0 locations; 3000+ ppm: 0 locations.

Screenshot einer Messung der Zentralbibliothek im KAP1 in Düsseldorf von August 2025 mit einem durchschnittlichen CO2-Wert von 547ppm

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Aurel Wünsch @aurel.indoorco2map.com · 02/06/2026

And this inverted way to deal with risks in face of uncertainty compared to has been laid out quite clearly in not only the Final Report of the SARS Commission but also the UK Inquiry and probably many more less prominent examples. It is not about a single pathogen, but about the general approach.

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Aurel Wünsch @aurel.indoorco2map.com · 25/05/2026

Added 2 new chart types to the analysis page in addition to the boxplots. These convey the Information way better on first glance than boxplots I think. And the more I use the GO IAQS(tandard) from @goaqs.bsky.social, the more I am convinced that 3 categorys are enough to provide an overview

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Aurel Wünsch @aurel.indoorco2map.com · 23/05/2026

It's not much of a difference but the citation suggestion has 2025 in it , so probably created 2025, released 2026.

screenshot of the copyright and licensing page which has the following suggested citation: Suggested citation. Infection prevention and control guideline for Ebola and Marburg diseases. Geneva: World Health
Organization; 2025. Licence: CC BY-NC-SA 3.0 IGO.

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Aurel Wünsch @aurel.indoorco2map.com · 20/05/2026

One of the many great things about the Indoor Air Quality Meetings I attended so far is that there actually is good air quality, just open Doors are often enough to achieve that. 470ppm is just barely above baseline levels. And having a screen promin placed is a great communication tool.

A photo of the panel at the World Health Assembly High-Level dialogue on Healthy Indoor Air which shows a large display with various Indoor Air Quality parameters of the room. CO2 is at 471ppm

Photo of the open doors at the venue towards the balcony

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Aurel Wünsch @aurel.indoorco2map.com · 18/05/2026

Looking forward to attend this Meeting in Geneva tomorrow. Glad to see the strong support of France on this topic. Will be in Geneva this afternoon already.

Announcement Poster of the Hig-Level Dialogue on Healthy Indoor Air - a side event of the World Health Assembly in Geneva

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Aurel Wünsch @aurel.indoorco2map.com · 13/05/2026

As a minor clarification - doctor's are among the worst categories measured so far but there are 3 worse categories (when restricting to categories with n>=10 locations): pubs, nightclubs and veterinarie,s albeit still with low sample size and doesn't really make it any better for doctor's offices.

Box plot comparing indoor CO₂ levels (ppm) by location type — 30 groups. Filters: all countries; all location types; Apr 11, 2024–May 13, 2026. Data: 4.420 locations · 11.116 visits shown · 30 location types (highest median CO₂). Groups with lowest CO₂: pub (n=62): median 1,241 ppm, Q1 814 ppm, Q3 1,912 ppm, IQR 1,098 ppm; whiskers 535 ppm–3,371 ppm; 4 outliers, highest 7,114 ppm. nightclub (n=12): median 1,208 ppm, Q1 833 ppm, Q3 1,890 ppm, IQR 1,057 ppm; whiskers 494 ppm–2,162 ppm; 2 outliers, highest 7,648 ppm. veterinary (n=18): median 1,046 ppm, Q1 842 ppm, Q3 1,279 ppm, IQR 437 ppm; whiskers 614 ppm–1,865 ppm; 3 outliers, highest 2,148 ppm. Groups with highest CO₂: aerodrome (n=13): median 747 ppm, Q1 609 ppm, Q3 846 ppm, IQR 237 ppm; whiskers 520 ppm–1,078 ppm; no outliers. centre (n=14): median 746 ppm, Q1 627 ppm, Q3 944 ppm, IQR 317 ppm; whiskers 504 ppm–1,354 ppm; 1 outlier, highest 2,179 ppm. clinic (n=56): median 744 ppm, Q1 661 ppm, Q3 893 ppm, IQR 233 ppm; whiskers 510 ppm–1,106 ppm; 3 outliers, highest 1,487 ppm. The 24 middle groups — doctors, conference_centre, college, supermarket, physiotherapist, place_of_worship, wholesale, theatre, government, community_centre, sports_centre, variety_store, confectionery, school, bar, charity, hairdresser, terminal, arts_centre, cinema, social_facility, chemist, dentist, gift — have medians between 747 ppm and 945 ppm; whiskers 394 ppm–2,613 ppm; 191 outliers combined. The IQR (interquartile range) spans from Q1 (25th percentile) to Q3 (75th percentile), covering the middle 50% of values; a smaller IQR indicates a more consistent distribution.

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Aurel Wünsch @aurel.indoorco2map.com · 12/05/2026

The whole article is worth reading, but if you don't then at least read the final one. Structurally I think what's needed for better handling of such a situation is a mandatory outbreak/quarantine insurance which every passenger pays and in such cases they get compensated with 1000€/day quarantine.

Screenshot of the final paragraph of the text linked in the Article from the post by Donald Miltion with the following text: WHO’s default recommendations for severe pathogens with respiratory transmission potential should begin from a precautionary airborne-risk framework — including respirators, ventilation optimisation, and portable HEPA filtration — and only be relaxed if evidence later demonstrates that such measures are unnecessary. The costs of implementing these protections early are modest; the costs of delaying them during a high-consequence outbreak may be profound.

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Aurel Wünsch @aurel.indoorco2map.com · 05/05/2026

archive.is/6RdK9 Referenz zur AI-Psychose von Mister Selfish-Meme höchstpersönlich.

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Aurel Wünsch @aurel.indoorco2map.com · 05/05/2026

The mistake is to do Direct Air Capture outdoors instead of in Classrooms, Doctor's offices, pubs, or in packed underground music clubs where you get sometimes get 5x to 10x the outdoor CO2 concentrations. /s

Histogram of indoor CO₂ distribution (percentage of locations per CO₂ bin, bin size: 400 ppm). Filters: Germany; Doctor's Offices; Apr 11, 2024–May 5, 2026. Data: 164 locations · 353 visits. Peak bin: 800–1200 ppm at 40.9%. 18% between 1200 and 1600ppm, 6% between 1600 and 2000% ppm. 4% higher than 2000ppm

Box plot comparing indoor CO₂ levels (ppm) by location type — 5 groups. Filters: all countries; Pubs, Variety Stores, Theatres, Nightclubs, Doctor's Offices; Apr 11, 2024–May 5, 2026. Data: 535 locations · 1.029 visits shown · 5 location types (most frequently measured). variety_store (n=98): median 827 ppm, Q1 683 ppm, Q3 1,074 ppm, IQR 391 ppm; whiskers 468 ppm–1,573 ppm; 7 outliers, highest 2,037 ppm. theatre (n=144): median 868 ppm, Q1 685 ppm, Q3 1,183 ppm, IQR 498 ppm; whiskers 485 ppm–1,853 ppm; 8 outliers, highest 2,761 ppm. doctors (n=221): median 946 ppm, Q1 756 ppm, Q3 1,206 ppm, IQR 450 ppm; whiskers 473 ppm–1,870 ppm; 8 outliers, highest 2,975 ppm. nightclub (n=12): median 1,208 ppm, Q1 833 ppm, Q3 1,890 ppm, IQR 1,057 ppm; whiskers 494 ppm–2,162 ppm; 2 outliers, highest 7,648 ppm. pub (n=60): median 1,251 ppm, Q1 810 ppm, Q3 1,936 ppm, IQR 1,126 ppm; whiskers 535 ppm–3,371 ppm; 4 outliers, highest 7,114 ppm. The IQR (interquartile range) spans from Q1 (25th percentile) to Q3 (75th percentile), covering the middle 50% of values; a smaller IQR indicates a more consistent distribution.

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Aurel Wünsch @aurel.indoorco2map.com · 03/05/2026

The real crazy thing is that they have a two people dying and just kept going cruising around - instead of you know maybe travelling to a place with better medical care than having 1 doctor on board.

The first victim was a 70-year-old man who died on the ship and whose body was removed in the British territory of Saint Helena in the South Atlantic, South Africa's Health Department said in a statement. The man's wife collapsed at an airport in South Africa trying to take a flight to her home country of the Netherlands, the department said. She died at a nearby hospital.

screenshot of text excerpt of the linked article: The department identified the patient in intensive care in a hospital in Johannesburg as a British national. It said that person fell ill near Ascension Island, another remote island in the Atlantic, after the ship left Saint Helena and was transferred from there to South Africa.

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Aurel Wünsch @aurel.indoorco2map.com · 02/05/2026

Nächsten Samstag sind die #Liegenddemos ( @liegenddemo.bsky.social ) in Solidarität mit ME/CFS Betroffenen. Ich werde in Leipzig dabei sein. Nach der Demo gegen 16 Uhr gibt es außerdem ein (vermutlich kleines) Treffen von Menschen die am Innenraumluftqualität interessiert sind am Bach-Denkmal.

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Aurel Wünsch @aurel.indoorco2map.com · 29/04/2026

I added some new features to the analysis page. One of them is the ability to generate social-media-ready images of the charts - including ALT-text. I also added an (by default enabled) option to adjust all measurements to local time - which makes more sense when comparing across continents than UTC

Image of the tool which generates social media ready graphics. there are 3 layout options (landscape, square, portrait mode). There is a option to generate ALT-Text and copy it to the clipboard. The alt text describing the chart is the following: Box plot comparing indoor CO₂ levels (ppm) by time period in Doctor's Offices — 12 groups. Filters: all countries; Doctor's Offices; Apr 11, 2024–Apr 29, 2026. Data: 380 locations · 468 visits shown · 12 periods. Groups with lowest CO₂: Jan (n=47): median 1,005 ppm, Q1 875 ppm, Q3 1,457 ppm, IQR 582 ppm; whiskers 616–2,307 ppm; 2 outliers, highest 3,287 ppm. Feb (n=39): median 1,096 ppm, Q1 985 ppm, Q3 1,446 ppm, IQR 461 ppm; whiskers 616–1,937 ppm; 2 outliers, highest 2,360 ppm. Mar (n=35): median 996 ppm, Q1 821 ppm, Q3 1,173 ppm, IQR 352 ppm; whiskers 565–1,583 ppm; 2 outliers, highest 3,880 ppm. Groups with highest CO₂: Oct (n=49): median 1,077 ppm, Q1 778 ppm, Q3 1,406 ppm, IQR 628 ppm; whiskers 513–2,149 ppm; 2 outliers, highest 3,312 ppm. Nov (n=62): median 1,083 ppm, Q1 862 ppm, Q3 1,498 ppm, IQR 636 ppm; whiskers 576–2,331 ppm; 2 outliers, highest 2,826 ppm. Dec (n=43): median 1,046 ppm, Q1 819 ppm, Q3 1,241 ppm, IQR 422 ppm; whiskers 566–1,828 ppm; 2 outliers, highest 2,348 ppm. The 6 middle groups — Apr, May, Jun, Jul, Aug, Sep — have medians between 665 and 942 ppm; whiskers 473–1,798 ppm; 6 outliers combined. The IQR (interquartile range) spans from Q1 (25th percentile) to Q3 (75th percentile), covering the middle 50% of values; a smaller IQR indicates a more consistent distribution.

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Aurel Wünsch @aurel.indoorco2map.com · 26/04/2026

You can also do things like comparing stores of the same brand/chain in different countries, although the sample sizes become rather small in most cases then.

Comparison of CO2 levels for LIDL supermarkets across multiple countries. Note that switzerland and france have a very low samples size of 6 and 4 and this is chart is more for illustrative purposes of what's possible.
Germany LIDLs (n=179) have 1221ppm in median, Austria (n=28) have 1094, Switzerland has 859 and France 768

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Aurel Wünsch @aurel.indoorco2map.com · 26/04/2026

And also between Weekday and Saturday. Same restriction to only compare locations which have measurements both in Summer and Winter applies here.

Comparison of german supermarkets between weekdays with CO2 levels of 936ppm median and saturday with 1009ppm

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Aurel Wünsch @aurel.indoorco2map.com · 26/04/2026

But also between summer half-year (lower) and winter half-year. The option "match locations across groups" is enabled here, so this means the comparison is restricted to locations which have measurements both in summer and winter - this avoids a lot of possible biases which could happen otherwise.

Comparison of german supermarkets between summer half-year with CO2 levels of 896ppm median and winter half-year with 963ppm

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Aurel Wünsch @aurel.indoorco2map.com · 26/04/2026

The following posts will focus on supermarkets which are sort of the fruitfly of our project so far as they are by far the most numerous measured location so drilling down the data there is where sample sizes still keep somewhat sufficient. CO2-levels vary by country ...

Boxplot comparing CO₂ levels (in ppm) measured in supermarkets across 10 countries, sorted by highest median CO₂. Data from IndoorCO2Map covers 2,376 locations and 6,976 visits.
Median CO₂ values per country:

Netherlands (n=40): 961 ppm
Germany (n=1,601): 941 ppm
Austria (n=267): 932 ppm
Switzerland (n=61): 854 ppm
United Kingdom (n=65): 782 ppm
France (n=57): 776 ppm
United States (n=108): 768 ppm
Italy (n=29): 695 ppm
Sweden (n=24): 669 ppm
Spain (n=34): 648 ppm

Germany has the largest sample and the most outliers, with extreme values reaching nearly 3,000 ppm. Most countries show typical ranges between roughly 500 and 1,500 ppm. Southern European countries (Italy, Spain) and Sweden show the lowest medians, while Central European countries cluster at the top.

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Aurel Wünsch @aurel.indoorco2map.com · 26/04/2026

In addition to the new App Version I also added a new data explorer tool to the indoorco2map.com website at indoorco2map.com/analysis.html . As there are 25000 total measurement time series now (20000 for buildings and 5000 for transit) at least some subsets have decent sample size.

A screenshot of the new data explorer website with a boxplot showing the 20 most measured types of locations sorted by median CO2-levels in descending order. worst 5 are: Doctors at 945ppm, supermarkets at 895ppm, theatres at 864, cinemas at 766ppm and chemists at 749ppm. best 5 are bakerys at 672ppm, furniture shops at 648ppm, clothes shops at 633ppm, fast food stores at 630ppm and do-it-yourself shops (hardware stores) at 576ppm

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Aurel Wünsch @aurel.indoorco2map.com · 25/04/2026

A history page has been added which shows all your own recordings. This is stored locally on your phone, it can be exported to a file and imported on other devices - so you can keep your data if you change phones etc. This feature can be disabled in the settings.

Image of the history screen which shows all recordings you did yourself. it displays them in a chart and ther also is a an option to show it on the map and a grouping option and search filter.

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Aurel Wünsch @aurel.indoorco2map.com · 25/04/2026

Transit Mode now features a map preview of the selected transit line - this is especially useful as some lines have non-intuitive names not related to train numbers (especially for long distance routes).

A screenshot of the app showing the selected tram route on a map

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Aurel Wünsch @aurel.indoorco2map.com · 25/04/2026

The completely rewritten new version indoorco2map.com App is now available for both Android and iPhone. It removes the biggest problems of the old App, especially location search which is now very reliable and also a lot faster (usually <1 second) but also features dozens of small improvements. 1/n

A screenshot of the new main menu of the app, showing a sensor selection dropdown, the possibility to search for buildings and public transit in vicinity. sorting by distance or alphabet, a text search and the option to start the recording

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Aurel Wünsch @aurel.indoorco2map.com · 09/04/2026

Kritisieren kann man das nicht explizit darauf hingewiesen wird dass der Grundpreis enthalten ist und auch kein Vergleich mit der Vergangenheit dabei ist, aber der Wert ist schon einigermaßen belastbar.

Folie vom BDEW mit folgendem text: Methodische Erläuterungen zum Strompreisdurchschnitt
Haushalte
Der Preisdurchschnitt enthält Tarifprodukte und Grundversorgungstarife, welche zum Berechnungszeitpunkt abschließbar
waren. Diese werden mit der Vertragsstruktur gemäß Angabe der Bundesnetzagentur gewichtet (2024: 78% Tarifprodukte, 22%
Grundversorgungstarife). Zudem erfolgt eine Durchschnittsberechnung der Strompreise auf Gemeindeebene mit
anschließender Gewichtung anhand der Anzahl der Einwohner.
Der ermittelte Preis bildet nicht den Preisdurchschnitt der bestehenden Vertragsverhältnisse bzw. Absatzmengen ab, d. h. es
erfolgt auch keine Mengengewichtung. Der Grundpreis ist im Preis in ct/kWh für einen Jahresverbrauch von 3.500 kWh anteilig
enthalten. Sondertarife wie spezielle Ökostromtarife mit Aufschlag, Heizstromtarife, Wärmepumpentarife, Koppeltarife
mit anderen Produkten (z. B. Gas, Telekommunikation) o. ä. sind nicht berücksichtigt.

Folie vom BDEW mit Diagramm zum Strompreis für Haushalt als Jahreswerte (3500 kWh, inkl. Grundpreis, nur Neukundentarife). Nominale Werte
2015: 29.6 cent / kWh
2016: 29.8
2017: 30.4
2018: 30.3
2019: 31.2
2020: 32.3
2021: 32.8
2022: 46.3
2023: 47.0
2024: 40.1
2025: 39.3
2026: 37.2

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Aurel Wünsch @aurel.indoorco2map.com · 06/03/2026

your Datasheet recommends recalibrating above ~2500m (750hPa) though.

Excerpt of Aranet Datasheet with the following text: CO2 sensor of the device is calibrated at standard atmospheric pressure. CO2 readings are pressure compensated
and comply with the specifications down to 750 hPa. If the device has to be used at high altitude for a prolonged
period of time, manual calibration of the unit should be performed for optimal performance. It is not intended to use
the device higher than 4000 m (13’000 ft) above the sea level.

URL: https://assets.aranet.com/documents/Aranet_Datasheet_TDSPC0H3_Aranet4_HOME_1.pdf

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Aurel Wünsch @aurel.indoorco2map.com · 05/03/2026

Rather than calling out single locations, the IndoorCO2map can you show many locations - with the caveat that those are just short Measurements taking at some Point in the past - but some Locations have been measured often already and is still a first indication.

Map of the IndoorCO2map Project with the filter to only show cafés enabled, map is showing large parts of europe with measurements mostly in german speaking countries and the UK. Roughly the same amount of locations with Good and Moderate Air Quality according to the GO AQS Standard and a few locations with Unhealthy Air Quality

Map of the IndoorCO2map Project with the filter to only show restaurants enabled, map is showing large parts of europe with measurements mostly in german speaking countries and the UK. Roughly the same amount of locations with Good and Moderate Air Quality according to the GO AQS Standard but also many locations with Unhealthy Air Quality

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Aurel Wünsch @aurel.indoorco2map.com · 25/02/2026

However I think the benefits of the GO IAQS to use an easy understandable System which hopefully will find widespread adoption far outweigh those small, and somewhat subjective, issues, especially as standards are not set in stone but evolve. As with all standards there is always a risk...

A three-panel comic from xkcd by Randall Munroe titled “How Standards Proliferate (see: A/C chargers, character encodings, instant messaging, etc.).”

Panel 1: A caption reads, “Situation: There are 14 competing standards.”

Panel 2: Two stick figures talk. One says, “14?! Ridiculous! We need to develop one universal standard that covers everyone’s use cases.” The other responds, “Yeah!”

Panel 3: A caption reads, “Soon: Situation: There are 15 competing standards.”

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Aurel Wünsch @aurel.indoorco2map.com · 25/02/2026

The second change is the addition of a slider to filter the map for locations with certain air quality regarding CO2. While the GO IAQS Standard just uses 3 different colors, there is a finer grained scale from 10 (best) to 0 (worst) which is used by this filter.

Screenshot of the indoorCO2Map showing Los Angeles to San Francisco and surroundings with the filter set to only display location with Good Air Quality according to GO IAQS CO2-scores

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Aurel Wünsch @aurel.indoorco2map.com · 25/02/2026

The Indoorco2map.com Website got two small updates, both related to the adoption of the Global Open Indoor Air Quality Standards (GO IAQS) from @goaqs.bsky.social. First change is the option to display the Air Quality of the locations in its 3-Color scheme representing Good / Moderate / Unhealthy.

Screenshot of the website showing Europe with thousands of map markers in the 3-color Scheme used by the GO IAQS Standard

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Aurel Wünsch @aurel.indoorco2map.com · 22/02/2026

Verglichen mit anderen Werten von anderen Konzerten ist das ja noch einigermaßen im Rahmen des Schlechten. (der Airspot Health mit dem das aufgenommen wurde kann auch über 10000ppm messen, daher nicht wundern über die ~12000ppm - allerdings ist es nur bis 5000 kalibriert, danach wirds ungenauer.

Diagramm einer Messung im 100 Club in London mit einem Durchschnitt von 7648 ppm und Spitzenwerfen von fast 12000ppm

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Aurel Wünsch @aurel.indoorco2map.com · 14/02/2026

Nicht besonders gut übersetzt, "Gefahr für die Öffentliche Gesundheit" statt "gesundheitsschädlich" sollte da stehen

Text of the endangerement finding: On December 7, 2009, the Administrator signed two distinct findings regarding greenhouse gases under section 202(a) of the Clean Air Act:

Endangerment Finding: The Administrator finds that the current and projected concentrations of the six key well-mixed greenhouse gases—carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6)—in the atmosphere threaten the public health and welfare of current and future generations.
Cause or Contribute Finding: The Administrator finds that the combined emissions of these well-mixed greenhouse gases from new motor vehicles and new motor vehicle engines contribute to the greenhouse gas pollution that threatens public health and welfare.

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Aurel Wünsch @aurel.indoorco2map.com · 10/02/2026

Just to add 3) to those very important points: waiting rooms (at least in doctor's offices) also tend to have really high CO2-levels at least in the data recorded so far in the indoorco2map project - which is heavily skewed towards german and austrian locations.

Boxplot-Chart showing CO2-levels for different types of locations measured in the indoorCO2map.com citizen science project. Doctors offices are the 3rd worst category (just pubs and community centers have higher median values). These measurements are mostly taken in germany so far so might not be generalisable and they are measurements both in waiting rooms and also treatment rooms

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Aurel Wünsch @aurel.indoorco2map.com · 25/01/2026

Ich poste echt ungern Screenshots von X aber hier ist wes vermutlich nötig - wenn Bovino selbst Posts retweeted in den er von FOX NEWS als "ICE Chief" bezeichnet wird - dann ist er de-facto "ICE Chief".

Screenshot of an X post with embedded video with text: Chicago ICE Chief Greg Bovino tells
@HARRISFAULKNER
he’ll meet with a federal judge every day - and says she’ll see “firsthand how bad things really are.”

What’s your reaction?

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Aurel Wünsch @aurel.indoorco2map.com · 24/01/2026

Time request help from the crowd! One of the things I want to add to IndoorCO2map is Support for stationary CO2-Sensors which transmit continously (be it from stores, restaurants, museums etc. I have the technical side mostly done. Now I am looking into which devices are best suited for this

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Aurel Wünsch @aurel.indoorco2map.com · 07/01/2026

Das ist schon der Zentrale Punkt sowohl des Kapitels zur Ökobilanz als auch der Einleitung und das sollte dann schon sehr belastbar sein wenn man mit "Faktor 4" argumentiert.

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