The Clean Air Act (CAA) was established in 1970 by Congress to protect public health and welfare. Since then, it’s undergone two amendments and has achieved many milestones. The United States’ air pollution has significantly decreased as a result of the CAA and more recent air quality regulations.
However, some air quality regulations, such as the National Ambient Air Quality Standards (NAAQS), have become more complex and stringent in the last few years, which poses a significant challenge to economic activity.
For example, the recent short-term NAAQS are much more difficult to meet than the original longer-term standards. This is because the conservative assumptions in AERMOD (the EPA’s accepted regulatory model) are more critical when dealing with these very stringent short-term standards. Many studies have shown that the results from AERMOD significantly overestimate ambient concentrations.
Some of the currently used assumptions that can cause significant overpredictions include:
- Unrealistic building downwash effects calculated by the Building Profile Input Program for PRIME (BPIP) used by AERMOD
- Assuming continuous maximum emissions
- Pairing maximum background concentrations with the modeled (predicted) values
- Simplistic haul road characterization
- Inappropriate wind speeds to characterize wind-blown dust from storage piles
- Inappropriate friction velocity to characterize low-speed winds under stable conditions
If your project has stalled because of air modeling requirements or if you need an alternative to less-accurate, overly-conservative modeling methods, we have scientifically-based, validated alternatives that can support your project while protecting air quality.
Our advanced modeling services include:
- Equivalent Building Dimensions (EBD)
- Haul road characterizations based on site-specific dispersion
- Fugitive dust and particulate emissions from storage piles and exposed areas
- Many more services
Unlike any other wind engineering consulting firm, we promote advanced techniques to alleviate excessive conservatism in permit modeling to a reasonable level that still protects public health.
With experience dating back to the inception of the Clean Air Act, our experts do more than run the models; we understand the theory, know where the models work, and recognize where they don’t work. If a model doesn’t work, we have unique tools to overcome these areas. This difference will save you time and money.
We use verified methods to reduce excess conservatism that lead to highly unrealistic results, while meeting NAAQS requirements and protecting air quality.