Baltimore's Air Pollution: What's The Main Culprit?

Baltimore's air quality has improved over the last few decades, but air pollution remains a pressing issue for the city. In 2020, Baltimore experienced elevated levels of air pollution on 43 days, and the city has consistently exceeded the federal limit on unhealthy ozone days since 1996. While the air quality is generally acceptable, sensitive groups may experience symptoms from long-term exposure, and the pollution poses a serious health risk for all residents. The primary sources of air pollution in Baltimore are traffic emissions and incinerators, with the Wheelabrator incinerator being the single largest stationary source.

Ground-level ozone pollution

Baltimore has struggled to meet federal attainment levels for ozone pollution, with the city exceeding the limit of unhealthy ozone days since at least 1996. From 2016 to 2018, Baltimore experienced a weighted average of 14.2 unhealthy ozone days, far above the federal limit of 3.2, earning the city an "F" rating from the American Lung Association. The Washington-Baltimore-Arlington metro area was ranked 20th for the worst ozone levels among 229 metropolitan areas in the 2019 "State of the Air" report.

Ozone pollution in Baltimore is largely attributed to power plant and vehicle emissions, with a significant contribution from upwind states such as Pennsylvania, West Virginia, Indiana, Ohio, and Kentucky. The Maryland Department of the Environment (MDE) estimates that about 70% of Baltimore's smog originates from these out-of-state sources. Additionally, local sources like building heating, traffic, and industry also play a role in the city's ozone problem.

To address the issue of ground-level ozone pollution, Baltimore has implemented stricter regulations on industry and vehicles, as well as adopting new technologies for more efficient energy use. Transitioning to electric vehicles or greener transportation, investing in renewable energies, and working with upwind states to reduce transboundary emissions are further strategies that Baltimore can employ to mitigate ground-level ozone pollution and improve air quality for its residents.

Trash incinerators

The Wheelabrator incinerator emits thousands of pounds of greenhouse gases and toxic substances, including carbon dioxide, hydrochloric acid, formaldehyde, nitrogen oxides, and volatile organic compounds. These emissions contribute to the formation of ozone, a major air pollutant in Baltimore. The incinerator has received subsidies and financial incentives from the state for producing renewable energy, but its environmental impact has led to concerns and protests from residents and activists.

In addition to Wheelabrator, there are other trash incinerators in Baltimore that contribute to air pollution. One such incinerator is the WIN Waste incinerator, which has been the subject of a civil rights complaint filed with the U.S. Environmental Protection Agency. The complaint argues that the incinerator disproportionately harms residents of predominantly Black and Hispanic neighborhoods nearby.

The issue of trash incinerators in Baltimore highlights the complex trade-offs between waste management, renewable energy production, and the environmental and health impacts of air pollution. While incinerators can reduce landfill waste, their emissions contribute to respiratory issues, heart conditions, and other serious health problems for nearby residents. As a result, there is a growing movement towards a ""zero-waste" future, with increased recycling and composting to reduce the amount of garbage sent to incinerators.

Vehicle emissions

The Baltimore Regional Transportation Board must work to ensure that emissions from the region's transportation network remain below the limit set in the State Implementation Plan (SIP). To achieve this, the Maryland Department of the Environment uses a computer model to estimate future vehicle emissions from the transportation system in Baltimore. This model predicts future travel on the region's roadways and transit ways, and the data is used to inform the federally-required transportation conformity process.

Nitrogen oxides and volatile organic compounds are two harmful emissions produced by vehicles. These compounds are precursors to ground-level ozone pollution, which has long posed challenges for Baltimore. Since 1996, the city has exceeded the federal limit on unhealthy ozone days, and the problem has worsened in recent years. From 2016 to 2018, Baltimore experienced a weighted average of 14.2 unhealthy ozone days, several times above the federal limit of 3.2.

Weather

One of the primary weather-related factors influencing air pollution in Baltimore is temperature inversion. This phenomenon occurs when a layer of warm air traps pollution close to the ground, preventing it from dissipating into the atmosphere. Temperature inversion is more common during the winter months, which helps explain why Baltimore experiences increased pollution levels during this season. The use of heating systems in homes and buildings also contributes to higher emissions during winter, further degrading air quality.

Summer in Baltimore brings its own set of challenges. As temperatures rise, ozone levels tend to increase. Ground-level ozone, a major component of smog, is formed through the reaction of nitrogen oxides and volatile organic compounds in the presence of sunlight, a process accelerated by higher temperatures. Consequently, the hotter and brighter summer days can lead to elevated ozone levels, posing a significant health risk to residents.

The dynamic nature of weather patterns also affects air pollution in Baltimore. For instance, forest fires on the West Coast can impact air quality in the city. The smoke and pollutants released during these fires may be carried by winds, leading to decreased air quality in Baltimore and other downwind regions. This illustrates how weather patterns, including wind direction and speed, can influence the distribution and concentration of air pollutants.

While Baltimore has made progress in reducing overall pollution levels, the weather continues to play a pivotal role in shaping the city's air quality. By understanding these interactions, authorities can implement targeted measures to mitigate the impact of weather-related pollution spikes and safeguard the health of Baltimore's residents.

Particulate matter (PM2.5)

Particulate matter, or PM2.5, refers to fine particles that are approximately one-thirtieth of the width of a human hair or smaller. In Baltimore, PM2.5 levels have generally improved since 1996, meeting federal attainment levels for 24-hour and annual targets since 2010. However, 2019 saw an increase in PM2.5 levels, with February, July, August, November, and December of that year experiencing "moderate" PM2.5 levels according to the US Air Quality Index (AQI).

The increase in PM2.5 levels during the winter months can be attributed to several factors. One factor is the increased emissions from home and building heating, as well as from car idling. Another factor is the occurrence of cool air inversion events, where cold surface-level air becomes trapped by a warmer air layer above, causing pollution emissions to accumulate and creating low-hanging smog.

Baltimore's elevated PM2.5 levels during the summer are often associated with increased ozone levels. Ozone is a secondary pollutant formed when nitrogen oxides and volatile organic compounds, emitted by sources such as the Wheelabrator trash incinerator, react with sunlight and heat. While Baltimore has never met federal attainment levels for ozone pollution, PM2.5 levels have shown consistent year-over-year improvements, except for the anomaly in 2019.

The improvement in PM2.5 levels in Baltimore can be attributed to the efforts of the Maryland government and federal regulations. More stringent regulations on industry and vehicles, as well as new technologies for more efficient energy, have contributed to the overall improvement in air quality. However, the relaxation of EPA regulations and reduced enforcement during the Trump administration and the COVID-19 pandemic may have contributed to the recent increases in PM2.5 levels.

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