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Air Quality Planning

Air pollution comes from many different sources - factories, power plants, various small businesses like dry cleaners – but it also comes from mobile sources. Mobile sources include cars, trucks, buses, trains, ships, lawn mowers, and construction equipment.

Transportation-related air pollution is pollution that results from the operation of cars, trucks, buses, trains, and ships. Although transportation is only one cause of the air pollution in the Baltimore region, it is a sizeable one.

What we do for cleaner air

In addition to working closely with member jurisdictions and the Maryland Departments of the Environment and Transportation, the Baltimore Regional Transportation Board (BRTB) does a number of things to address transportation and air quality issues and to promote cleaner air. 

Policy and Planning 

  • How Far Can We Get? Study - The How Far Can We Get? Study was initiated by the Baltimore Regional Transportation Board in fall 2013 to better understand the level of emission reductions that are achievable through a reasonable level of reduction measure implementation, and to inform the region’s next long range transportation plan, Maximize2040. The How Far Can We Get Oversight Committee was formed to handle the decision-making and oversight of the study, conducted by BMC staff. The objectives of the study were to understand:
    • The level of existing and future greenhouse gas (GHG) emissions from the region’s transportation system;
    • How far the region can reduce GHG emissions through transportation emission reduction measures (TERMs); and,
    • Options to address GHG’s in the Baltimore region’s long-range transportation plan, Maximize2040.
  • The federal fuel economy and Tier 3/low sulfur fuel programs for light-duty vehicles from 2017-2025 can reduce GHG emissions 11.7% in 2030 and 17.6% in 2040. Additionally, the recommended strategies from this report, the Vehicle Technology Plus/Marketing Scenario, estimate a 2.9% reduction in 2030 and a 9.8% reduction in 2040. When combined these strategies may result in up to a 15% and 27% reduction in GHG emissions in 2030 and 2040, respectively.
  • Air Quality Conformity - Because the Baltimore region is not currently meeting federal air quality standards, the BRTB must show that the emissions resulting from transportation plans, programs, and federally-funded projects are within emissions limits set by the State of Maryland’s air quality plan. Every transportation plan for the region is studied to see what effect the projects could have on air quality. This process is called “transportation conformity”, or just “conformity.”

  • Interagency Consultation Group - The ICG meets monthly to discuss current transportation topics and how they affect the region’s air quality.

Outreach and education

To help reduce emissions from transportation sources, the Baltimore Metropolitan Council conducts several outreach efforts designed to educate people about the relationship between driving and air quality.  These include: 

  • Bike to Work Day – hundreds of cyclists join early morning pep rallies at several locations throughout the region. 
  • Outreach appearances at community events – our staff, joined by volunteers from the Clean Commute Partnership, talk to thousands of people one-on-one about transportation and air quality and to promote Clean Commuting options such as riding mass transit or carpooling.
  • Commuter "thank-you" events – we show our appreciation to folks who use area park and ride facilities.
  • Media campaigns – TV, radio, and print ads are used to spread the word about transportation and air quality
  • Environmental News Brief - The Environmental News Brief e-newsletter serves as a resource to inform stakeholders and the public about news related to air quality and transportation in the Baltimore region.  
  • Clean Air Partners - In 1997, the Baltimore Metropolitan Council and the Metropolitan Washington Council of Governments co-chartered the Clean Air Partners organization. This unique public/private partnership educates residents of the Baltimore and Washington regions about the health dangers of air pollution. Clean Air Partners also promotes simple things people can do to help reduce the amount of pollutants released in our air. As part of Clean Air Partners, BMC staff members take part in: 
    • Coordinating the Baltimore region’s Air Quality Action Days Program
    • Providing communications and support to the over two hundred organizations participating in the Air Quality Action Days program
    • Recruiting new members for Clean Air Partners
    • Visiting community events and schools to promote awareness of air quality issues
    • Answering media question about air pollution

Air Quality 101

What Air Pollutants in the Baltimore Region Does Traffic Contribute to?

Traffic from vehicles (cars, trucks, etc.) in the Baltimore region contributes to fine particulate matter (fine soot) and ground-level ozone, as well as other pollutants. Ground-level ozone and fine particulate matter are a major concern because the region is not reaching federal standards for these pollutants. 

How is Ground-Level Ozone Formed?

Ground-level ozone is formed by the combination of volatile organic compounds (VOCs), nitrogen oxides (NOX) and sunlight. VOCs come from gasoline, paint, solvents, pesticides and charcoal lighter fluid. They are also formed naturally. NOX comes from cars, trucks, and buses, as well as power plants, and coal-burning stoves.

VOCs + NO+ Sunlight = Ozone

How is Particulate Matter Formed?

Particulate matter is formed both directly and indirectly. It is formed directly by motor vehicles exhaust, fires, power plants, construction dust, and unpaved roads.

EPA - Direct release of Particles

Particulate matter is formed indirectly when products of fuel combustion, sunlight, and water vapor react with each other to create particles.

EPA - Reaction

Facts on the Baltimore Region's Air Quality

Fact #

The Baltimore region is not currently meeting federal standards for 8-hour ground-level ozone and fine particulate matter (or fine soot).

Fact #2

The Baltimore/Washington D.C./Northern Virginia region was ranked 13th for ozone pollution by the American Lung Association in their State of the Air 2005 report.

Fact #3

Harford County ranked within the top 25 most polluted counties in the country, in terms of ozone pollution, by the American Lung Association’s State of the Air 2012 report. At the same time, Harford County ranks as one of the cleanest counties in the country for short-term particle pollution.

Fact #4

The Baltimore/Washington D.C./Northern Virginia region was ranked 22nd for short-term particle pollution by the American Lung Association in their State of the Air 2012 report.

Fact #5

Baltimore City ranked in the top 25 most polluted jurisdictions for short-term particle pollution, by the American Lung Association’s State of the Air 2005 report.

Why should we care?

The issue of air pollution in the Baltimore region is a critical one because ozone and fine particulates can cause respiratory systems and other serious health problems in sensitive populations. In addition, fine particulates can increase rates of cardiovascular illness and may reduce life span.

Air Quality Conformity

Air Quality Conformity

On December 16th, 2014, the U.S. Environmental Protection Agency finalized their decision that the Baltimore region has reached the national ambient air quality standard (or, NAAQS) for fine particulate matter, and continues to stay below unhealthy levels.

>> Find out more

What is transportation conformity?

Transportation conformity is the process that is used to review the current transportation plan and program in a region to ensure they conform with to the state’s air quality plan. Each state’s air quality plan, also known as the State Implementation Plan, determines how the states will meet National Ambient Air Quality Standards (NAAQS).

Why does the Baltimore Regional Transportation Board go through transportation conformity?

As the Metropolitan Planning Organization for a region that is not currently reaching federal air quality standards, the Baltimore Regional Transportation Board (BRTB) is required to go through the process of transportation conformity every time there is a new transportation plan, program or federally-funded project.

How do we rate? Air quality in the Baltimore region

  • Ground-level Ozone – In July 2012, the Baltimore region was designated “moderate” nonattainment for the 8-hour ground-level ozone standard set in 2008. However, over the past few years the region has experienced lower levels of ozone pollution. As of 2015, the region is meeting the 2008 8-hour ozone NAAQS. At the same time, a new, stricter ozone standard of 0.070 parts per million was set in October 2015. The region will continue to work to reduce ozone-forming emissions. 
  • Fine Particulate Matter - On December 16th, the U.S. EPA finalized their decision that the Baltimore region has reached the annual PM2.5 NAAQS for fine particulate matter, and continues to stay below unhealthy levels . As part of the Clean Air Act, the State of Maryland must ensure that the region’s air quality continues to stay at healthy levels for PM2.5. To do this, the State has developed a maintenance state implementation plan, or SIP. The maintenance SIP demonstrates how the region will continue to maintain safe levels out to 2025.
  • Carbon Monoxide – The Baltimore region is also in a maintenance phase for the carbon monoxide standard. The federal standard for carbon monoxide has already been reached and must stay the same or below this level.

Working together to improve air quality

The transportation conformity process is coordinated through the Interagency Consultation Group, a subcommittee of the Baltimore Regional Transportation Board (BRTB).

The group looks at state air quality goals and the ability of the transportation plans and programs to meet those goals.

Recent Conformity Determinations

Congestion Mitigation and Air Quality Improvement Program (CMAQ)

Congestion Mitigation and Air Quality Improvement Program (CMAQ)

The Baltimore Regional Transportation Board’s (BRTB) Congestion Mitigation and Air Quality (CMAQ) Improvement Program competitively selects projects that can help the Baltimore region reduce emissions from mobile sources and meet National Ambient Air Quality Standards. CMAQ eligible projects must be able to reduce air pollution emissions and in some cases reduce traffic congestion. The CMAQ program is administered by the Federal Highway Administration and the Federal Transit Administration and is provided to state and local governments.

The call for project applications is currently closed.

Previously-Selected Projects

The following table provides a listing of projects that were selected by the BRTB to receive federal CMAQ funds during prior rounds of funding through the BRTB CMAQ Competitive Selection Process. Once the projects receive BRTB approval, the project sponsors must then apply for and received approval from FHWA or FTA before moving forward and putting the project out for bid.

>> See Previously Selected Projects 

>> Download the Application Guide 

Bicycle/Pedestrian Project Technical Form

Traffic Flow Improvement Project Technical Form

Clean Vehicle Project Technical Form

Diesel Retrofit Project Technical Form

Idle Reduction Project Technical Form

Travel Demand Management Project Technical Form

Other Project Type Technical Form

Air Quality Modeling

Air Quality Modeling

Why do we do air quality modeling?

The Baltimore region does not currently meet federal air quality standards for ozone and fine particulates. As a result, the region is required to estimate future air pollution emissions that will result from projects in the  Baltimore Regional Long Range Transportation Plan and the Transportation Improvement Program.

Through air quality modeling, we can determine the potential impact that highway and transit projects in transportation plans and programs will have on our air quality.* 

In addition, this modeling process ensures that regional transportation plans do not delay the timely attainment of federal air quality standards. This process is called a conformity determination. To learn more about conformity determinations, visit our page on Air Quality Conformity

How is air quality modeling performed?

Emissions that result from transportation projects in the Baltimore region are estimated using a computer model.** After Baltimore Metropolitan Council staff runs the travel demand model to determine demand on the region’s transportation system in future years, air pollution emissions modeling is performed. 

Travel demand estimates from the region’s travel demand model are combined with environmental assumptions (such as temperature) and information on mobile emissions control programs (such as inspection and maintenance programs) to become inputs to the air quality model. Then, the air quality model is run and outputs data that is then converted into estimates of air pollutant emissions. 

This process provides estimates of emissions of nitrogen oxides, volatile organic compounds, and carbon monoxide (in tons per day) as well as fine particulates, or fine soot (in tons per year), resulting from the region’s transportation system.

Which BMC committees are responsible for air quality modeling?

The Interagency Consultation Group is the committee that focuses on air quality issues. It is responsible for coordinating the transportation conformity process, and overseeing the air quality modeling process. The Technical Committee is responsible for reviewing all technical analyses associated with conformity, such as modeling assumptions, data collection and accuracy. 

For more information on Environmental Protection Agency's air quality model for vehicle emissions, called the MOBILE emissions model, visit:

* The Clean Air Act Amendments of 1990 require that regions that are not reaching federal standards for air quality must test transportation plans and programs to make sure that their air quality is not made worse by their implementation.

** The U.S. Environmental Protection Agency has procedures for calculating air emissions estimates in future years. BMC maintains an air quality modeling process that meets the EPA’s requirements.



What is ground-level ozone? 

Ozone is a gas that is formed by the combination of nitrogen oxides, volatile organic compounds, and sunlight. Ground-level ozone is what people commonly refer to as smog.

How does ground-level ozone affect me? 

Ground-level ozone can be harmful to your health if you work or exercise outdoors on a regular basis in the summer, if you have respiratory problems, or if you are a child, or elderly. Short term effects of ground-level ozone include pain when taking a deep breath, coughing, eye irritation, and aggravation of respiratory illnesses like asthma. Long term effects of ozone include reduced lung function and lung damage.

Why are children especially vulnerable to ground-level ozone?

  • They play outside on summer afternoons
  • Their lungs are still developing
  • They breathe more rapidly than adults
  • They inhale more pollution per pound of body weight than adults do

When is ground-level ozone a problem?

Ground-level ozone is mainly a problem between May and September every year.

What can I do?

What is the Baltimore Regional Transportation Board doing to improve air quality? 

The BRTB checks each transportation plan and program in the region to make sure that the ground-level ozone problem in the Baltimore region does not get worse as a result of transportation projects. This also helps us to make sure that these plans do not prevent us from meeting the federal ground-level ozone standard. This is done through what is called the Conformity process.  Learn about how the BRTB addresses transportation-related air pollution.

Particulate Matter

Particulate Matter

Particulate matter is a serious problem for the regionParticulate matter pollution is a serious and growing concern. Recent studies show that such pollution is harmful, even at current health standards set by the federal government. New standards address this by working to reduce the levels of the most harmful types of particles.

What is particulate matter?

Particulate matter is made of the particles and droplets found in the air. By themselves, these particles and droplets are invisible to the naked eye. But all together, they can appear as clouds or a fog-like haze.

"Fine particles" (1/28 the diameter of a human hair - see picture below) come from many different sources, including industrial and residential combustion and vehicle exhaust. Thousands of these tiny particles would fit on the period at the end of this sentence. Larger particulate matter (coarse particles) also have many sources. These include things like dust from construction, landfills, and stone crushing; wind-blown dust; and road dust. 

Image showing particulate matter size compared to a human hair
 Click photo to enlarge.  Source:

What are examples of particulate matter?

Dust, ash, mist, smoke, soot or fumes.

How does particulate matter affect me?

Both coarse and fine particles are a health concern. Because of their small size, they can get into sensitive areas of the lungs and heart.

Fine particles are the biggest concern because they are linked to the most serious effects. They can cause a persistent cough, wheezing, and physical pain, as well as worsen conditions such as asthma, bronchitis, and emphysema. Long-term exposure may increase the rate of respiratory (lung) and cardiovascular (heart) illness and reduce life span.

Is this a new problem?

Particulate matter has been a problem for years. However, recent studies show that major health problems can result from exposure even below current standards. So, the federal government made these standards stricter in order to protect human health and the environment.

What can you do?

  • Reduce travel on days with poor air quality.
  • Avoid using your wood stove and fireplace on days that have poor air quality.
  • Avoid using leaf blowers and other dust-producing equipment.
  • Drive slowly on unpaved roads and other dirt surfaces.

What is the Baltimore Regional Transportation Board doing?The BRTB checks each transportation plan and program in the region to make sure that the fine particulate matter problem in the Baltimore region does not get worse as a result of transportation projects. This also helps us to make sure that these plans do not prevent us from meeting the federal fine particulate matter standard. This is done through what is called the Conformity process.

For more information:
Sara Tomlinson, This email address is being protected from spambots. You need JavaScript enabled to view it. or 410-732-0500 x1035.
Russ Ulrich, This email address is being protected from spambots. You need JavaScript enabled to view it. or 410-732-9575.


Last Updated on Tuesday, 15 August 2017 12:29