Submitted:
28 April 2026
Posted:
29 April 2026
You are already at the latest version
Abstract
Keywords:
1. Introduction
2. Related Work
2.1. Health Burden and Monitoring Urgency
2.2. Low-Cost Sensor Networks
2.3. Deep Learning for Air Quality Prediction
2.4. Image-Based AQI Estimation: Prior Art and Comparative Analysis
2.5. Research Gap
3. Methodology
3.1. Preprocessing
3.2. Model Architectures
3.2.1. VGG16 Hybrid Model
3.2.2. EfficientNetB0 Hybrid Model
3.3. Training Protocol
3.4. Evaluation Metrics
3.5. Use of Artificial Intelligence Tools
4. Results
4.1. Training Dynamics
4.2. Test Set Evaluation
4.3. True vs. Predicted AQI Scatter Plot
4.4. Prediction Error Distribution
5. Discussion
5.1. Interpreting the Negative R2 Values
5.2. Dataset Scale as the Primary Bottleneck
5.3. Contextualization of Indicators In Comparison with Previous Work
5.4. Label Noise from Sensor-Image Geographic Mismatch
5.5. Visual Confounders: Illumination and Scene Diversity
5.6. Right-Skewed Error Distribution: Implications
5.7. EfficientNetB0 vs. VGG16: Architectural Interpretation
5.8. Recommendations for Future Work
6. Conclusion
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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| Study | Architecture | Images | Target | Best metric |
|---|---|---|---|---|
| [15] | CNN–LSTM (VGG/ResNet) | 3,549 | AQI | R2 = 0.94 |
| [16] | ResNet CNN | 8,000+ | AQI | R2 = 0.71 |
| [11] | Multimodal CNN | 6,000+ | AQI | R2 = 0.65 |
| [17] | Deep CNN + attention | 15,000+ | AQI | R2 = 0.78 |
| [18] | EfficientNet + metadata | 12,000+ | PM2.5 | MAE = 18 g/m3 |
| [19] | CNN–LSTM (VGG16) | 7,213 | AQI | |
| [20] | DCNN (smartphone) | ∼1,000 | PM2.5 | — |
| [21] | AQI-Net (CNN+Grad-CAM) | 11,000+ | AQI | Acc = 99.8% |
| Present study | VGG16 / EffNetB0 | 1,014 | AQI | RMSE = 66.49 |
| Split | Samples | Proportion | Usage |
|---|---|---|---|
| Training | 710 | 70.0% | Model optimisation |
| Validation | 151 | 14.9% | Early stopping, hyperparameter tuning |
| Test | 153 | 15.1% | Final held-out evaluation |
| Total | 1,014 | 100% | — |
| VGG16 | EfficientNetB0 | |||
|---|---|---|---|---|
| Epoch | Val Loss | Val MAE | Val Loss | Val MAE |
| 1 | 1.8117 | 2.2562 | 0.6921 | 1.1066 |
| 3 | 1.5057 | 1.9558 | 0.7002 | 1.1084 |
| 5 | 1.4238 | 1.8677 | 0.6903 | 1.0896 |
| 10 | 1.2896 | 1.7282 | — | — |
| 13 | 1.2200 | 1.6582 | — | — |
| 15 | 1.2378 | 1.6823 | — | — |
| Model | RMSE | MAE | R2 |
|---|---|---|---|
| VGG16 + PM2.5 hybrid | 78.71 | 58.78 | −0.794 |
| EfficientNetB0 + PM2.5 hybrid | 66.49 | 49.00 | −0.280 |
| Improvement (EffNet vs VGG) | −15.5% | −16.6% | +0.51 abs. |
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