Executive Summary

Key Results and Highlights through 2013

Chapter 1:
CASTNET Overview

Background

Cooperating Networks

Locations of Monitoring Sites

Supreme Court Upholds Cross-State Air Pollution Rule

Measurements Recorded at CASTNET Sites

Quality Assurance Program

Estimating Dry, Wet, and Total Deposition

Building Tribal Partnerships with CASTNET Monitoring Sites

Chapter 2:
Ozone Concentrations

National Ambient Air Quality Standards for Ozone

Eight-Hour Ozone Concentrations

W126 Values for 2011 through 2013

Chapter 3:
Trace-level Gas Concentrations

Trace-level NO_y and Ozone

Trace-level and Filter Pack Sulfur Dioxide Concentrations

Enhancements to Air Quality and Deposition Monitoring in New York

Trace-level NO_y and Filter Pack Total Nitrate Concentrations

Update on the Ammonia Monitoring Network (AMoN)

Chapter 4:
Atmospheric Concentrations

Sufur Dioxide Concentrations

A Comparison of Temperature Measurements from Collocated Mechanically and Naturally Aspirated Sensors Operated at Three CASTNET Sites

Particulate Sulfate Concentrations

Air Quality Studies in National Parks in the Bakken Formation

Total Nitrate Concentrations

Particulate Ammonium Concentrations

Results for 2013 Environment Canada Proficiency Testing

Chapter 5:
Atmospheric Deposition

Sulfur Deposition

The Application and Use of Critical Loads for USDA Forest Service Management and Policy Decisions

Nitrogen Deposition

MLM/Bowker/PRISM Estimates of Trends in Dry and Total Sulfur and Nitrogen Deposition