A worldwide environmental service company (headquartered in Westford, Massachusetts, USA) that has developed: dispersion models that accommodate complex terrain and aerodynamic downwash; visibility models; hazardous air pollutant dispersion models; and others for facilities located in dispersion environments where standard models are inaccurate.

A consultant group based in Mississauga, Ontario, Canada (with multiple offices in Canada) who offer air dispersion modeling services. The dispersion models utilized include Ontario Regulation 346 as well as these U.S. EPA models: Screen3, ISCST3, and AERMOD.

ECCI is a consulting firm with offices in Little Rock, Arkansas, USA. Services include consulting, Clean Air Act permitting/modeling, industrial risk, SPCC, hazardous waste and a full range of engineering services.

Yamada Science & Art Corporation (YSA), located in Santa Fe, New Mexico, USA, specializes in computer modeling of atmospheric airflows and the dispersion of airborne materials over complex terrain. YSA developed, markets, and provides user support for the three-dimensional atmospheric models HOTMAC and RAPTAD.

Environmental management consultants located in Columbus, Missouri, USA. Their services include: air quality monitoring; air permitting; and air dispersion modeling involved in evaluating the offsite consequences of accidental releases and of air toxics emissions.

An environmental consulting firm based in Southern California, USA, whose services include air dispersion modeling, stationary source permitting, and emission inventories, allotments, and mitigations.

A firm of environmental consultants and engineers with corporate headquarters in Syracuse, New York and other offices nation-wide in the USA as well as Canada and the UK. Their services include air permitting, air regulation assistance and air dispersion modeling.

Consultants, based in Dallas, Texas, USA, whose air quality consulting includes dispersion modeling services.

A wind engineering consulting firm (located in Fort Collins, Colorado, USA) that offers wind tunnel modeling of pollutant transport and dispersion involving complex building and terrain situations.

The Centre for Atmospheric Sciences is a research and consultancy group within the Indian Institute of Technology at Delhi, India that offers atmospheric dispersion modeling.