CALPUFF is no longer a regulatory model for the US EPA

on . . Hits: 3941

calpuff recommended model EPA   The website of the Support Center for Regulatory Atmospheric Modeling (SCRAM) no longer includes the CALPUFF model as a recommended dispersion model. This means that one of the most widely dispersion model used for odour modelling is not recommended by the US EPA any more. This decision has serious consequences for the odour community.

   The U.S. Environmental Protection Agency (US EPA) originally published the Guideline on Air Quality Models in 1978. Since then, a few revisions of the Guideline have been carried out. In 2003, this Guideline was modified to include CALPUFF as one of the preferred model. This model was removed from the "preferred list" in May, 22 2017 (and now from the website). allegedly due to concerns about its capabilities to deal with long-range transportation of pollutants. This is no argument to exclude this model from the recommended list, as it is widely used for other purposes, different from long-range transportation. For example, when dealing with the calculation of the odour impact of a facility.

   The US EPA has a list of "recommended dispersion models" and another one of "alternative models". The Gaussian AERMOD plume model and the CALPUFF lagrangian puff model were included in the list of recommended dispersion models. There is a lot to say about these two lists but, in short, the recommended models were the ones used for Environmental Impact Assessments (EIA) not only in USA, but also in many other countries of the world.

  One of the main reasons why CALPUFF and AERMOD were used all over the world was that they are freely available and open source. Another important reason was that they were recommended by a regulatory administration. There are not many dispersion models recommended by regulatory agencies.

   So, why is the US EPA leaving a more advanced modelling system like CALPUFF out of the list of recommended models alleging "concerns about its ability to deal with long-range transportation of pollutants", when this is just one of the many uses that this model has?

   Maybe one of the reasons is that AERMOD* is developed by the US EPA and the American Meteorological Society (AMS), a public non-profit organization, while CALPUFF is developed by Exponent, a private company. Perhaps the changes in the ownership of the model in the recent years might have arisen some concerns in the EPA. Another reason could be that the leader of the CALPUFF project Joe Scire is unfortunately out of the project, although there is still a great group of people behind the project.

   Nobody really knows the reason for this exclusion based only in one criteria, but this is already bad news for the odour community.


*The name AERMOD is derived as follows: AMS and EPA Regulatory MODel.

   If you find this article interesting, you might be also interested in these articles:


Comments (1)

This comment was minimized by the moderator on the site

The alternative model list is an open list where any dispersion model can be used, as long as it is "suited for the purpose of the study".

The decision of the suitability of a model is frequently a dilemma for the plant environmental manager...

The alternative model list is an open list where any dispersion model can be used, as long as it is "suited for the purpose of the study".

The decision of the suitability of a model is frequently a dilemma for the plant environmental manager who does not know what model to use or the cost difference between models in the achievement of their end goal: obtaining an Environmental Authorisation. It is also a dilemma for environmental technicians who evaluate EIA projects in their achievement of their ultimate goal: A better environment for their community.

That is, in practical terms, the vast majority of environmental administration technicians that are evaluating an EIA will accept anything that comes from a consultancy company, as long as it is justified as "suited for purpose".
Before this change in the guideline, the US EPA recommended the AERMOD model to estimate air quality at a local level (up to 50 km), leaving CALPUFF for other cases such as complex land topography, where uses were not standard and where wind circulation could render steady state estimations redundant. That is, if there were sea or lake breezes, wind flows near coastlines, prevailing calm conditions, thermal inversions, recirculation and spraying conditions. In practice, CALPUFF had to be the model in use for odour impact assessment due to that odour is a complex case.

Read More
There are no comments posted here yet

Leave your comments

  1. Posting comment as a guest.
Attachments (0 / 3)
Share Your Location

Please note that this site uses cookies in order to work properly.

See more about our cookie policy Learn more

I understand

Please read the following to learn more about our cookies policy:


What are cookies?

   A cookie is a text file stored in a user’s web browser on any device they use to access a website that holds information regarding the user’s visit, such as preferences. When the user returns, the browser provides the cookie with the stored information to the site.

What cookies are used for?

   Cookies are used for adjusting a website’s content to fit a user’s preferences and optimize the website. They store useful information that improve the user’s experience of a website. They are most commonly used for:

  •     Recognizing the type of device a user is browsing with and any preferences applied to optimize the website specifically for the device.
  •     Creating statistics that help website owners to understand how their users interact with their website, which allows them to improve their structure and content.

What types of cookies are used?

   There are two types of cookies: persistent cookies and session cookies. Persistent cookies remain on your hard drive for a period of time specified in the cookie’s file parameters or until removed manually. When you return to a website and it requires you to login again despite previously storing your login information, it is usually because the persistent cookie expired; this helps to increase security while maintaining accessibility.

   Session cookies, on the other hand, are used temporarily and expire once the website or browser is closed. They are used to track user activity on a website during a single visit. When a website requires that you verify your age or location once every visit before allowing you to view content and without requiring additional personal details, that is a session cookie at work.

Do cookies include personal data?

   If there is a need for the collection of personal information, such as for creating accounts, then cookies may store personal information. However, it is required by data protection law that users are informed of the collection of personal data. This data will also be encrypted to render it inaccessible for unauthorized users.

Managing cookies

   By default, browsers are configured to accept cookies. However, these settings may be changed to block cookies entirely, or to inform the user each time they are used. Detailed information about cookies and the options associated with them are available in each browsers’ settings.

Which cookies does collect collect cookies for 2 purposes:

  • Register statistical data.
  • Set language preferences.

   In addition we use third party cookies through Statcounter to collect different data.

StatCounter Analytics Cookies

   StatCounter is a web analytics service. We use StatCounter to track activity on our website. These stats help us to understand how people are interacting with our website and to improve the design and functionality of our site so that we can offer a better online experience to our visitors. If you visit, a StatCounter analytics cookie (called "is_unique") may  be placed in your browser.  This cookie is used only to determine whether you are a first-time or returning visitor and to estimate unique visits to the site. No personal information is stored in the cookie.

Refuse Statcounter cookies.

You may set your browser to refuse/accept StatCounter analytics cookies by clicking here.


    • Your decision to refuse/accept StatCounter analytics cookies applies to all websites which use the StatCounter service (including the StatCounter site itself).
    • If you refuse all StatCounter analytics cookie, a refusal cookie (called "refusal_cookie") will be set to remember this preference and any existing StatCounter analytics cookies in your browser will be destroyed.
    • If you delete/remove/destroy the refusal cookie, you must revisit this page in order to re-set your preference.
    • The refusal cookie is set only for your current browser and machine. If you use multiple browsers/machines, you must set a refusal cookie in each case.
    • You can also change your cookie settings directly in your browser. Learn more about cookies and how to manage them here:
    • Or you can learn about how to adjust cookie settings for specific browsers here: