Air Quality Services

ERG’s internationally recognized air quality specialists support federal, regional, state, local, and tribal government agencies in their work to ensure that all citizens have safe, healthy air to breathe. To understand air pollution sources and levels, we identify and characterize point, nonpoint (area), mobile, and natural air pollution sources; develop emission factors and air emission inventories; and perform air quality modeling. In parallel, we support regulatory development and implementation to reduce ambient air pollution. For example, we identify, evaluate, and recommend viable emission control options; analyze regulatory impacts; provide technical support for drafting rule language and responding to comments; and develop guidance and training for regulated communities. In addition, ERG air quality engineers and scientists review and prepare permits, work that covers hundreds of facilities nationwide and spans virtually every major air quality rule.

Regulatory Development
  • New Source Performance Standards (NSPS) rule development support
  • National Emission Standards for Hazardous Air Pollutants/Maximum Achievable Control Technology (NESHAP/MACT) rule development support
  • GHG rule development and implementation support
  • Pollution control feasibility evaluations
  • Primary and secondary environmental and energy impact analyses
  • Cost and economic impact analyses
  • Compliance monitoring and recordkeeping procedures development
  • Response to public comments
  • Rule implementation assistance, guidance, and training
Emission Inventory Development
  • Criteria pollutants, hazardous air pollutants, and greenhouse gases
  • Point, nonpoint (area), mobile, and natural emission sectors
  • Emission factor development
  • Development of emission estimation methodologies
  • Guidance document development
  • Geographic information systems (GIS) spatial allocations
  • Emission inventory projections
Air Quality Permitting
  • All levels of permit application review and preparation
    • Title V and minor source operating permits
    • Prevention of Significant Deterioration (PSD) permits
    • Minor source and minor modification New Source Review (NSR) permits
  • Review and development of emission calculations
    • Verification of emission calculations
    • Development of emission calculation methodologies
    • Review of stack test reports
    • Determination of site-specific emission factors
  • Determination of applicable federal, state, and local regulations
  • Development of permit conditions and requirements for monitoring, recordkeeping, and reporting
  • Control technology review and preparation
    • Best Available Control Technology (BACT)
    • Reasonably Available Control Technology (RACT)
    • Maximum Achievable Control Technology (MACT)
  • Review of required air quality modeling analyses
Source Characterization and Modeling
  • Characterization of emission processes and sources
  • Correlation of emission sources and ambient concentrations
  • Analysis of emission and ambient concentration trends
  • Emission, air dispersion, and photochemical modeling


Service Area Leads

Monika Chandra

I am inspired every day by my work with clients and colleagues dedicated to improving our environment—and by our shared goal of developing superior, technically sound solutions to some of our nation’s most challenging environmental issues.

Monika Chandra

John Crenshaw

Throughout my career, I have taken satisfaction that my work has focused on improving the environment. In all my projects supporting federal and state regulatory programs, I strive to make sure that our clients understand all the options available to them and that the regulatory analyses on which government decisions are made are accurately documented and technically sound.

John Crenshaw

Jason Huckaby

I love the challenges and diversity of the air regulatory development work I do at ERG. To help clients protect human health and the environment, while also being mindful of the relevant economic and technical realities, I am continually learning new and emerging information about industrial and air pollution control processes relevant to affected industrial sectors. I enjoy discovering and applying this information to help our clients achieve their goals. I can, and often do, learn something new every day!

Jason Huckaby

Regi Oommen

As a kid, I loved baseball, especially the statistics and data behind it. I would go through box scores in the paper the next day to keep track of my favorite team and players, logging the information into my Commodore 64. I enjoyed exploring the data and looking for trends. Working at ERG on a variety of emission inventory, ambient monitoring, and air quality modeling projects has allowed me to continue my passion for analyzing big data sets. And now I get to tell the story behind the data too.

Regi Oommen

Roy Oommen

Most of us come into this profession with a healthy sense of idealism, wanting to make a positive contribution to the environment. Looking back at the last 25 years, I can honestly say that what we do at ERG has made a difference. Sometimes small, sometimes big, but always positive. The type of work we do matters to the environment. I am fortunate to be working with people who genuinely care about doing good and doing a good job.

Roy Oommen

Mike Pring

I gained an appreciation for the environment growing up in Florida, where I enjoyed spending time in the great outdoors—camping, hiking, surfing, and working on the ‘farm’ at the Florida Agricultural Experiment Station. At ERG, my career has allowed me to contribute to the protection of our environment, while continually being challenged to learn new skills and become familiar with the wide variety of industrial activities that give rise to air pollution.

Mike Pring

Paula Fields Simms

After nearly three decades of consulting, it's still fun to come to work because there are always new challenges, new faces, and new opportunities to learn. I've worked on so many important projects, including developing the National Ambient Air Quality Standard for fine particles; estimating Mexico's first national emission inventory; and assessing the potential air quality impacts from oil and gas exploration on Alaska's North Slope. I've installed samplers to measure woodstove emissions in homes in Medford, Oregon, and even vacuumed the streets of Bangkok to collect silt loadings for a PM inventory. I cannot imagine a better career and would encourage anyone thinking about working in the environmental field to pursue it with passion.

Paula Fields Simms

Mae Thomas

I still remember watching the news when I was 12 years old and seeing a report about a polluted river. From that moment on, I wanted to be part of the solution. Working at ERG, I have been able to realize this goal and exercise my passions for learning new things, solving problems, and helping our clients reach their goals.

Mae Thomas

Darcy Wilson

I started working as an environmental scientist when the environmental impacts of acid rain were of great concern. Not long after that, I assisted on a project that examined how effectively fast-growth tree farms could remove carbon dioxide from the atmosphere. I soon realized I was very good at ‘counting things’ and that, in the air quality field, emission inventories form the basis of almost every project. My career focus on emission inventory development has been very diverse and continually offers new challenges and learning opportunities.

Darcy Wilson