# O2Quality vs 湿度計++

The clearest difference is in-app purchases: O2Quality at none against 湿度計++'s 4. O2Quality also leads on ads (none vs shown). 湿度計++'s advantage is update cadence (monthly vs every 5 months) and iOS requirement (15.6 vs 27.0). On price and device support there is nothing between them.

Both are free to download. 湿度計++ sells 4 one-off in-app purchases. O2Quality asks for nothing beyond the download.

O2Quality ships an update every 5 months, 湿度計++ monthly. The most recent releases landed on October 9, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | O2Quality | 湿度計++ |
| --- | --- | --- |
| Price | Free | Free |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 5 months | **Monthly** |
| Monetization | Free | — |
| Size | 11 MB | 62 MB |
| Requires iOS | 27.0 | **15.6** |
| Devices | iPhone, iPad, Mac | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Tomohiko Shimizu](https://appshunter.io/developer/436129129) | [hidehiko aihara](https://appshunter.io/developer/1178520609) |

## What reviewers say

### O2Quality

[App page](https://appshunter.io/ios/app/o2quality/id1570058656)

Provides real-time air quality information based on US and European Air Quality Index (AQI) standards. It forecasts pollutant levels for up to five days, including carbon monoxide, ozone, nitrogen dioxide, sulfur dioxide, PM2.5, and PM10.

**Highlights:** Real-time AQI reporting, US and European AQI standards, Forecasts for 6 pollutants, 5-day pollutant forecasts, Color-coded risk levels, Pollutant concentration data

**Features:** Vision Pro support

**In-app purchases:** none


### 湿度計++

[App page](https://appshunter.io/ios/app/plus-plus/id1633054315)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Coffee (Regular) | $0.49 | one-time |
| アプリケーション開発者への応援募金 | $1.99 | one-time |
| Coffee (Large) | $1.99 | one-time |
| Cake Set | $5.99 | one-time |


## Frequently asked questions

### Is O2Quality free?

O2Quality is free to download, with no in-app purchases.

### Is 湿度計++ free?

湿度計++ is free to download, with in-app purchases available.

### Do O2Quality or 湿度計++ have ads?

湿度計++ shows ads; O2Quality does not.

### Which is updated more often, O2Quality or 湿度計++?

O2Quality ships an update every 5 months, and 湿度計++ monthly. Most recently, O2Quality was updated on October 9, 2026 and 湿度計++ on October 14, 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.*