PM2.5 monitoring network

Continuing my exploration into aerosol studies I now explore the American IMPROVE initiative. IMPROVE stands for Interagency Monitoring of Protected Visual Environments. Their website defines the program as

a cooperative measurement effort between the U. S. Environmental Protection Agency (EPA), federal land management agencies, and state agencies. The network is designed to

1. Establish current visibility and aerosol conditions in 156 mandatory Class I areas (CIAs)  

2. Identify chemical species and emission sources responsible for existing anthropogenic
visibility impairment 

3. Document long-term trends for assessing progress towards the national visibility goal  

4. With the enactment of the Regional Haze Rule, provide regional haze monitoring
representing all visibility-protected federal CIAs where practical. 

They link to a cool feature VIEWS, which displays aerosol data for every type of particulate composition in the country. Below is IMPROVE aerosol PM2.5 levels from NYC from 2004-2010

As you can see there's a lot more 'dirty' aerosols in a big city than, say, Rocky Mountain, Colorado:

Sophisticated stuff. I really like how full-disclosure these websites are. Excel files, readable plots, publications galore. There is little to hide. Here's the geography of the IMPROVE network: