New annual PM2.5 NAAQS Effective May 6, 2024

Posted by on Friday, April 26th, 2024 in Newsletters

What’s Happening Now

EPA News

*HOT* New Annual PM2.5 NAAQS Published – As we noted previously, EPA announced changes to the annual PM2.5 National Ambient Air Quality Standard (NAAQS) back on February 7, 2024. The actual Reconsideration Rule was published in the Federal Register on March 6, 2024 and the new NAAQS becomes effective May 6, 2024. You can read the actual FR Notice here. The new level of the annual standard has been reduced by 25%, from 12 μg/m3 to 9 µg/m3.

EPA will be proposing an updated annual PM2.5 Significant Impact Level (SIL) that should be available on or before the effective date of the new NAAQS (May 6, 2024).

*HOT* EPA Considering Change to Secondary SO2 NAAQS – It looks like we’ll be seeing changes to another National Ambient Air Quality Standard, this time, for the secondary SO2 standard.  On April 3, 2024, EPA proposed to replace the current secondary SO2 standard of 0.5 ppm (or 1,300 μg/m3) over a 3-hour averaging period with a new annual secondary standard of 10-15 parts per billion (ppb) (or 26-39 μg/m3). A public hearing on this proposal will be held May 8, 2024. For more information on the hearing, go to and for more information on the proposal, check out

Conferences and Workshops

*HOT* 2024 Texas Commission on Environmental Quality Trade Fair – This year’s version of the TCEQ Trade Fair will be held May 14-15, 2024 at the Austin (TX) Convention Center. As always, this event will be chock-full of presentations on air quality permitting, other air, water, and waste issues, and oil/gas issues. Providence will be there (we’ll be in booth 321 in the Exhibitor Hall) and we hope to see you there, too. Click here for more information.

*HOT* The 2024 AWMA Annual Conference and Exhibition (ACE) will be held in Calgary, AB June 24-27, 2024. ACE is returning to the scene of the popular 2010 Conference, and this one should also be outstanding! Click here for more information on registration, etc.

*HOT* 2024 EPA Regional/State/Local Modelers Workshop – EPA will be holding its annual Regional/State/Local Modelers Workshop July 30-August 1, 2024 at the offices of the Colorado Department of Public Health and the Environment (CDPHE) in Denver, CO. There will be a public/stakeholder day on July 30.  For basic information on the Workshop click here and to see the draft workshop agenda click here.

*HOT* AWMA Modeling Conference “Guideline on Air Quality Models: A New Chapter” – The air quality modeling committee of AWMA has scheduled this specialty conference to be held at the Sheraton Raleigh Hotel in Raleigh, NC November 13-15, 2024. A Call for Abstracts should be announced shortly. Once we have more information, we will share that with you here in Providence/Oris Notes. You can also check out for more information as it is posted online.

If your company, organization, agency, State, etc. has an upcoming modeling or air quality-related event (virtual or otherwise) and you’d like it publicized in Providence/Oris Notes, please send that information to us at, and we’ll be happy to include it.

Providence Products

Simply the best!

Changes to Licensing in 2024

You may have received an email from us recently highlighting upcoming changes to our software licensing structure. The changes, to take effect after June 30, 2024, include:

• No new multi-user licenses will be issued/sold after June 30, 2024. Existing multi-user licenses will still be honored and renewable.
• Existing single user licenses may not be upgraded to multi-user after June 30, 2024. If you wish to upgrade before the deadline, please contact us ( immediately for a quote.
• No new Max-3 licenses will be issued/sold after June 30, 2024. Existing Max-3 licenses will still be honored and renewable.
• No changes to Enterprise licenses, air regulator licenses, or academic/research licenses.

To read all of the upcoming changes go to


BEEST 12.10 has been released!  BEEST 12.10 allows you to run AERMOD 23132 and AERMET 23132, but currently does not include an interface for the new COARE over-water algorithms in AERMET. It includes all of these great new features:

• *The AERMOD 23132 executable* (although the new keywords will be incorporated into BEEST 12.11
• *The AERMET 23132 executable*
• Support for new AERMOD 22112 alpha keywords SWPOINT, RLINEXT, and PLATFORM
• Ability to export new SWPOINT and RLINEXT source types to Google Earth
• The AerMinute GUI includes download access to the new 1-minute ASOS data site (National Center for Environmental Information or NCEI website — as was discussed in in October 2022 Providence/Oris Notes)
• We’ve added the ability to add receptors along an Other line (like a road or railroad)
• Reads the ArcGIS world file when the user opens a background map
• Updated Terrain File Converter to read the latest version of GDAL library files
• Added a warning in Receptor Options when the number of partitions is greater than the total number of receptors
• Added confirmation prompt when the user clicks the “Remove last day from output files” button in AerMet
• Added a list of ASOS station anemometer heights to guidance documents
• An updated WindRose utility
• And more!

We presented a webinar on the new features in BEEST 12.10 back on December 21, 2023. If you missed it, you can view the recording of it here.

Look for BEEST 12.11 to be out in May 2024. This update will include:

• AERMET GUI upgraded to include support for new PROG and COARE keywords;
• BEEST supports new AERMOD 23132 keywords;
• Added the ability to select all or none of the pollutants and years on the AERMOD Setup form.

As always, users in maintenance can download the most recent version of BEEST from

“Go BEEST Mode !” We still have plenty of Go BEEST Mode t-shirts! You can request one of those by emailing us at

AerScreen for Windows

AerScreen for Windows 4.04 is now out! The update has these new features/enhancements:

  • Runs AERMOD 23132
  • Terrain Files Converter has been updated to use Geospatial Data Abstraction Library 3.7
  • Terrain Files Converter User Manual has been updated

Users in maintenance can download the most recent version of AerScreen for Windows from


AERMOD Wizard 1.09 is out and includes these updates:

  • Updated AERMET version to 23132
  • Ability to download all of the EPA 2022 ambient monitoring data
  • Ability to export Class I areas and Class I area receptors to Google Earth
  • Ability to download ASOS data from the new NCEI website
  • Inclusion of the 2020 National Emissions Inventory (NEI) data set
  • And more!

We presented a webinar on the new features in AERMOD Wizard 1.09 back on February 1. If you missed it, you can click here to view the recording.

Users in maintenance can download AERMOD Wizard from

We’re off to use the Wizard!

If you have suggestions for an enhancement to any of our modeling software products, please let us know and we’ll do our best to incorporate it into the software ASAP!

Modeling Tip of the Month

This month’s tip relates to using the SCREEN3 and AERSCREEN models from within BEEST. If you have those model executables on your computer, you can call/invoke SCREEN3 or AERSCREEN from within your BEEST file.

Note the AERSCREEN icon in BEEST:

And the SCREEN3 icon:

The big advantage to calling these models from within BEEST is that, if you have multiple sources in your BEEST file, you can easily run SCREEN3 or AERSCREEN for any of the BEEST sources. In this example, we have a BEEST file with three sources and two buildings:

If we click the SCREEN3 icon, this form/screen comes up:

Notice that you can select which source you want to run SCREEN3 for AND you can pick which building you want to use (or just enter your values for building height, length, and width). You can then click Run and the process is just like a stand-alone SCREEN3 run.

Similarly, you can click the AERSCREEN icon to see this screen/form:

Selecting the source you want to model with AERSCREEN and clicking OK takes you directly to the AERSCREEN user interface:

Providence Training

Modeling skills ready for an upgrade? We can help!

We want to note that many folks use our classes as credit toward professional engineer continuing education requirements. Check with your state’s licensing board or the National Society of Professional Engineers (see here or here) for more information on what is required.

Essential Air Permitting

Providence’s next Essential Air Permitting class will be May 6, 2024 and it will be on-line. This class is tailored to those folks who are new to air permitting or perhaps new environmental managers who need a good overview of the basic issues related to air permitting. Topics such as statutes, applicability, netting, emission calculations, and Title V are just some of the areas that are covered. To register for this Essential Air Permitting class, click here.

AERMOD Modeling for Permits

Our next AERMOD Modeling for Permits class for 2024 will be May 7-8, 2024 and it will be on-line. If you are wanting to get started in air modeling, then this class is for you! If you want to register, please click here.

Advanced AERMOD

Similarly, our next Advanced AERMOD class will be May 9-10, 2024, and it will also be on-line.

Advanced AERMOD covers those topics that are near and dear to modelers, such as:

• NAAQS modeling for 1-hour NO2, 1-hour SO2, and 24-hour PM2.5 (including the new MAXDCONT Viewer)
• Meteorological data processing with AERMET/AERMINUTE/AERSURFACE
• Culpability Determination
• Background Concentrations
• Emission scalars and Hourly Emission Rate files
• Changes in Terrain Data Processing and
• AERMOD Wizard and its uses

To register for Advanced AERMOD, click here.

Just as a reminder, if you register more than 30 days before your AERMOD class(es), you will receive a $100 discount on the course fee (per class, per registrant).

On-demand Meteorological Data Processing webinar

We are planning to launch a new training option – on-demand webinars. The first of these to be released will be “Meteorological Data Processing for AERMOD”.  Look for it at coming soon.

On-demand AERSCREEN webinar

We will be releasing an on-demand training webinar for AERSCREEN.  Watch this space for details!

Don’t forget, if our schedule of classes doesn’t mesh with your schedule, or if you have several people that need to be trained at once, contact us about setting up your own onsite or online class.

2024 Class Dates

Here are our training dates for the rest of 2024.

Date Class Location
6-May Essential Air Permitting On-line
May 7-8 AERMOD Modeling for Permits On-line
May 9-10 Advanced AERMOD On-line
19-Aug Essential Air Permitting On-line
August 20-21 AERMOD Modeling for Permits On-line
August 22-23 Advanced AERMOD On-line
9-Dec Essential Air Permitting On-line
December 10-11 AERMOD Modeling for Permits On-line
December 12-13 Advanced AERMOD On-line

Providence Services


Our newer, faster BeestXpress processors run the new AERMOD 23132!

If you’ve never used our super-fast cloud-based BeestXpress before, now is the time. We have an on-demand webinar that steps you through the process of setting up an BeestXpress account and sending off your first BeestXpress run. You can view the webinar here. New BeestXpress users can complete their first run with up to 50 partitions absolutely FREE. Instructions about receiving the free run are given at the end of the webinar. Beyond the starter run BeestXpress will give you a per-run cost estimate before you begin. If you need help budgeting for BeestXpress, contact us for additional daily rate pricing options.

BeestXpress users have some great system enhancements to work with:

  • The “Job Details” webpage now displays the pollutant being modeled
  • The “Job Details” webpage now displays run progress for MAXDCONT calculations
  • Modeling runs with multiple partitions now include a combined AERMOD input file (*.DTA) in the output .ZIP file
  • Added an option to the “Submit Job” webpage that affects modeling runs with multiple partitions: the intermediate output files created by each partition can be omitted from the output .ZIP file
  • The “Job Search” webpage now includes the option to search by project number
  • Users have access to up to 99 partitions per AERMOD run

To date, BeestXpress has processed over 500,000 AERMOD runs.

BeestXpress users can log on at to take advantage of our AERMOD “force multiplier”. That AERMOD run that might have taken a day or two to process on your desktop computer can finish in an hour or less on BeestXpress. When time is money, BeestXpress is the best modeling return on investment there is!

Meteorological Data Processing Services

Do you need AERMOD-ready meteorological data? If so, we can help! Whether it’s running national weather service data or onsite monitor met data through the AERMET/AERMINUTE system, Providence has the background, know-how, and experience to have your data processed and ready for you ASAP. If you’d like more information, contact us at or

Consulting Solutions

One thing that we’re very proud of is the depth and range of our modeling experience and expertise. The kinds of air quality models we’ve used include all types, ranging from simple screening tools like SCREEN and AERSCREEN to plume models like ISC and AERMOD. The types of analyses include basic Significant Impact Level, NAAQS, PSD increment consumption, Class I analyses, air toxics and SIP attainment demonstrations. So, we’ve seen it all. To that end, should you or your clients need additional modeling assistance or just a second set of eyes to QA or peer review your modeling (ranging from initial protocol up to final submission), we stand ready to help. Feel free to contact us at 512‑258‑8855, 828‑628‑0634 or


Essential Air Permitting
May 6, 2024

AERMOD Modeling for Permits
May 7-8, 2024

Advanced AERMOD
May 9-10, 2024

TCEQ Environmental Trade Fair
May 14-15, 2024
Austin, TX

AWMA Annual Conference and Exhibition ACE
June 24-27, 2024
Calgary, AB

EPA Regional/State/Local Modelers Workshop
July 30 – August 1, 2024
Denver, CO

AWMA Specialty Conference – Guideline on Air Quality Models: A New Chapter
November 13-15, 2024
Raleigh, NC

Our complete class schedule can always be found at

For More Information:

Phone: (512) 258-8855
Visit our websites: (software, support, and training) (cloud-based high speed AERMOD)