# CO2 vs air

The clearest difference is update cadence: air at every 2 months against CO2's every 15 months. CO2's advantage is iOS requirement (12.0 vs 15.6). 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, air every 2 months. The most recent releases landed on October 6, 2026 and October 20, 2026 respectively.

## The numbers

| Metric | CO2 | air |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.0 (4 ratings)](https://appshunter.io/ios/app/air-q/id1512783605/reviews)** |
| Number of ratings | — | **4** |
| Positive reviews | — | 45.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 15 months | **Every 2 months** |
| Monetization | — | Free |
| Size | 39 MB | 24 MB |
| Requires iOS | **12.0** | 15.6 |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Deutsche Gesetzliche Unfallversicherung e.V. (DGUV)](https://appshunter.io/developer/487126969) | [air-Q](https://appshunter.io/developer/1512783604) |

## What reviewers say

### CO2

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

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

**In-app purchases:** none


### air

[App page](https://appshunter.io/ios/app/air-q/id1512783605)

Monitor your indoor air quality with this companion app for a specific device. Analyze data, identify pollution sources, and take steps to improve your health and performance.

**Highlights:** Monitor air quality, Graphical data analysis, Identify pollution sources, Improve health and performance, Manage air-Q device

**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 air free?

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

### Do CO2 or air have ads?

Neither CO2 nor air shows ads.

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

CO2 ships an update every 15 months, and air every 2 months. Most recently, CO2 was updated on October 6, 2026 and air on October 20, 2026.

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