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Air Monitoring and Reporting Forum: Natural Conditions Background Info

Natural Haze Levels Sensitivity: Assessment of Refinements to Estimates of Natural Conditions
The Haze Sensitivity Report (PDF) presents an extensive analysis of how particulate component concentrations under natural conditions are being currently estimated and how improvements might be made in those estimates when appropriate. The process used to determine the needed rate of reduction in haze from current measured conditions to estimated natural conditions in 2064 is thoroughly reviewed. The report is accompanied by a Sensitivity Calculator (XLS) that enables the reader to explore the impacts of user-selected changes in the concentrations of the various components of the aerosol to the slopes of the uniform rate of progress lines in each zone. (January 2008)

RFP - Regional Haze Rule: Default Natural Haze Levels Sensitivity Assessment (01/30/04) PDF or DOC

EPA Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule
This document provides default natural visibility estimates for the 20% worst days at each Class I area and describes how these estimates could be refined by the states.  (September 2003) PDF (5.4 MB)

MANE-VU Considerations and Proposed Approach to the Calculation of Natural Background Visibility Conditions at MANE-VU Class I Areas (06/10/04) PDF or DOC

  • Summary of Comments and Responses (06/10/04) PDF or DOC

VISTAS Examination of Refining Estimates of Natural Conditions
A draft report and presentation have been prepared by Ivar Tombach on behalf of VISTAS. In addition, a summary presentation is available given to the VISTAS air directors. (12/04/03)

Fast Aerosol Sensing Tools for Natural Event Tracking (FASTNET)
This project is being conducted by NESCAUM on behalf of all five RPOs.  The goal is to characterize natural haze conditions through the detailed analysis of major natural aerosol events from forest fires, windblown dust, and other sources.  Currently in its first year (and as a pilot), this project focuses on demonstrating the feasibility and utility of a system for Fast Aerosol Sensing Tools for Natural Event Tracking (FASTNET).  Click here for a progress report. (02/23/04)

Combined Aerosol Trajectory Tool (CATT)
This project is being conducted by MANE-VU on behalf of all five RPOs, and like FASTNET, can be used to analyze natural events.  Through the VIEWS aerosol chemical database, bundles of trajectories can be shown for specific sites, times, and aerosol conditions.  For example, back trajectories for Big Bend, TX, Upper Buffalo, AR, and Sipsy, AL, when the fine soil concentration was > 5 ug/m3 can be seen here.

NPS Issues Concerning Natural Conditions Estimation
This presentation was given by Bill Malm (National Park Service) at a MANE-VU science meeting in January 2004. (01/28/04) PDF (5.4 MB) or PPT (23 MB)

EPRI's Recommended Refinements to EPA's Guidance for Estimating Natural Conditions and Tracking Progress Under the Regional Haze Rule
This white paper was released by the Electric Power Research Institute (EPRI) in January 2004.  For further information, contact Naresh Kumar.  A presentation by Naresh given at the January 2004 MANE-VU science meeting is available in PDF or PPT format. (01/14/04)

Natural Visibility Conditions in the United States and the Effect of Transboundary Pollution
This project is being conducted by Dr. Daniel Jacob at Harvard University.  A description of the project (as proposed to EPRI) is available in PDF or DOC format, and a presentation of current results given at the November 2003 inter-RPO meeting in St. Loius is available in PDF or PPT formats. (11/04/03)


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