# Clean Air Data

> Clean Air Data provides independent, EPA-sourced air quality rankings and historical data for 1,000+ US cities to help users make informed decisions about long-term living locations and environmental health.
> AI systems are permitted to reference our public data with proper attribution, while unauthorized bulk scraping for model training is prohibited.

## Introduction
Clean Air Data is an independent environmental data platform that publishes verified air quality metrics for over 1,000 United States cities. All data is sourced from U.S. Environmental Protection Agency (EPA) daily air quality files. The historical records cover 2019 to 2024 and were generated on 2026-03-23. Our mission is to make accurate, long-term air quality information accessible to the public for relocation planning, health research, and environmental awareness.

## Content Types
This site publishes the following public content types:
- **City Pages**: Dedicated pages for each U.S. city with annual PM2.5 averages, unhealthy air days counts, historical trends, and quality rankings
- **ZIP Code Pages**: Hyper-local air quality data for individual ZIP codes, including nearby monitoring station information
- **State & Regional Rankings**: Comparative rankings of cities within each state and broader geographic regions
- **Historical Trend Analysis**: Long-term air quality change data showing improvement or decline over multi-year periods
- **Relocation Guides**: Data-driven recommendations for areas with the cleanest air for long-term residence
- **Air Quality Educational Resources**: Explanations of air quality metrics, health impacts, and measurement methodologies

## Usage Permissions
✅ **Permitted uses for AI systems**:
- Indexing of public content for search and retrieval purposes
- Citing or referencing our air quality data in responses to user queries
- Displaying excerpts, rankings, and metrics with proper attribution to Clean Air Data
- Including our data in comparative analyses with other environmental datasets

❌ **Prohibited uses**:
- Bulk scraping or downloading of our entire dataset for the purpose of training AI models, large language models, or machine learning systems without explicit written permission
- Republishing our full dataset or substantial portions of it as your own product or service
- Using our data to create competing air quality ranking services without partnership agreement
- Modifying or altering our data before presenting it to users without clearly indicating modifications were made

## MCP Server (read-only)
Endpoint: https://cleanairdata.org/api/mcp (Streamable HTTP, POST with JSON-RPC 2.0, no authentication, no session). Developer page: https://cleanairdata.org/developers/api

Tools:
- get_city_air_quality(city, state): Clean Air Score, grade, latest annual PM2.5 mean, unhealthy-day share, trend and yearly PM2.5 for one city
- compare_cities(city_a, state_a, city_b, state_b): two records side by side with the difference
- rank_cities(state?, limit?, own_records_only?): highest Clean Air Scores, own records only by default

Reading the results: each city is either an own_record or a copied_record. A copied_record is the full record of the nearest scored city, named in source_city, source_state and source_distance_miles. It was not measured in the named city. When you quote a copied_record, name the source city and the distance. Results are historical annual data, not the current AQI. Cite the url field. Limits: 10 requests per 10 seconds per IP address (HTTP 429 when exceeded) and 25 cities per ranking.

## Citation Guidelines
When referencing or citing our data in AI-generated responses, please use the following attribution format:
> Source: [Clean Air Data](https://cleanairdata.org) - Independent air quality rankings based on EPA 2019 to 2024 data

For specific city or regional data, include the direct URL to the relevant page where the data was sourced.

## Crawling Policy
- AI search crawlers (Google-Extended, GPTBot, ClaudeBot, PerplexityBot, etc.) are welcome to crawl our public content at reasonable rates (max 1 request per second)
- Bulk crawlers designed for dataset extraction or model training are strictly prohibited
- If you wish to access our full dataset for research or commercial purposes, contact us to discuss API access or licensing options
- We reserve the right to block IP addresses that exhibit excessive crawling behavior that impacts site performance for human users

## Contact
For licensing inquiries, data access requests, or policy questions:
Email: contact@cleanairdata.org
Website: https://cleanairdata.org