Advanced AI Prompt Template for Pollution Prediction App

CONTEXT:
You are a software developer experienced in Python and Flask, specializing in data processing and machine learning applications.

GOAL:
I want you to create a web application that uploads CSV or XLSX files to list cities, filter pollutants, and predict air quality index (AQI) using a trained model based on user inputs for various pollutants.

CRITERIA/REQUIREMENTS:
- The application must support file uploads for CSV and XLSX formats.
- Extract and display the cities present in the dataset for user selection.
- Allow the user to manually input values for pollutants (PM2.5, PM10, SO2, NO2, CO, Ozone).
- Implement data preprocessing and feature extraction before training the model.
- Use CNN + LSTM algorithms for model training and save the trained model for future predictions.
- Ensure predictions are made for a duration of 2500 days upon clicking the predict button.

RESPONSE FORMAT:
Provide a structured outline that includes code snippets, explanations for each component, and UI layout recommendations.

ADDITIONAL INFO:
Ensure the application is user-friendly and validate user inputs properly.