# CO2 vs AiringCycle

The clearest difference is update cadence: AiringCycle at every 3 weeks against CO2's every 15 months. AiringCycle also leads on iOS requirement (10.0 vs 12.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

CO2 ships an update every 15 months, AiringCycle every 3 weeks. The most recent releases landed on September 19, 2026 and September 23, 2026 respectively.

## The numbers

| Metric | CO2 | AiringCycle |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | — | 62.5% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 15 months | **Every 3 weeks** |
| Monetization | — | Free |
| Size | 39 MB | 15 MB |
| Requires iOS | 12.0 | **10.0** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Deutsche Gesetzliche Unfallversicherung e.V. (DGUV)](https://appshunter.io/developer/487126969) | [Corvin Hartmann](https://appshunter.io/developer/1436432188) |

## What reviewers say

### CO2

[App page](https://appshunter.io/ios/app/co2-timer/id1482287779)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### AiringCycle

[App page](https://appshunter.io/ios/app/airingcycle/id1537412154)

This app provides regular notifications to remind users to open and close windows for ventilation. Users can customize the duration for which windows should remain open and closed.

**Highlights:** Customizable airing schedules, Regular notification reminders, User-friendly interface, Promotes healthy indoor air quality

**Features:** Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is CO2 free?

CO2 is free to download, with no in-app purchases.

### Is AiringCycle free?

AiringCycle is free to download, with no in-app purchases.

### Do CO2 or AiringCycle have ads?

Neither CO2 nor AiringCycle shows ads.

### Which is updated more often, CO2 or AiringCycle?

CO2 ships an update every 15 months, and AiringCycle every 3 weeks. Most recently, CO2 was updated on September 19, 2026 and AiringCycle on September 23, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*