Cross-Platform Emissions Tracker App Development

I need a developer to create a cross-platform app for iOS and Android that tracks emissions data, specifically CO2, PM2.5, and NOx. The app will be focused on tracking emissions data.

Key Features:
- User authentication
- historical emissions data tracking
- Visualization of emissions data (charts, graphs)
- Notifications for emissions level changes
- Data export options (CSV, PDF)

Ideal Skills:
- Experience in cross-platform app development
- Proficiency in relevant programming languages (e.g., React Native, Flutter)
- Strong UI/UX design skills
- Familiarity with environmental data APIs
- Prior experience with data visualization in apps

Please share your portfolio and any relevant project experience.