Levels of ground-level ozone – or smog – in the Baltimore area rose between 2014 and 2015 and rose again between 2015 and 2016, according to the Maryland Department of the Environment’s(MDE) annual air quality report.

But the agency attributes the increase to the weather – unusually cool summers in 2013-2015 followed by an extremely hot summer in 2016 – and says the data show the state making significant long-term gains in reducing ozone, its biggest air quality problem for decades.

“While the hotter weather in 2016 inevitably led to an increase in ozone, the number of bad air days, the number of hours of bad air on those days, the daily peak and the geo-graphic expanse of bad air on those days were all less than what was seen during hot summers at the start of the decade,” the agency wrote in the Maryland Clean Air 2017 Progress Report, released this week.

“In 2016, the Baltimore and Washington, D.C. ozone non-attainment areas continued to meet the 2008 health-based ozone standard, and are extremely close to meeting the new, more-stringent, 2015 ozone standard that begins to be implemented in late 2017,” the docuemnt said.

Watchdog groups were less sanguine about the ozone information in the six-page report.

“We appreciate the important work that MDE has done, and continues to do, in order to reduce air pollution and improve public health,” said Leah Kelly, an attorney with the D.C.-based Environmental Integrity Project (EIP).

“However, as MDE recognizes, more work needs to be done,” she said, noting that attainment with federal standards is measured over a three-year period.

“When the ozone levels measured during the summer of 2017 and subsequent summers are figured in, it is possible that the Baltimore area will not meet either the EPA’s more relaxed 2008 ozone standard or the stronger 2015 standard,” Kelly said.

Looking at other measures, MDE saw signs of progress. Fine particulate levels in Maryland, for instance, are dropping every year.

Power Plants in Maryland and Beyond

The battle against ozone, which worsens and may cause asthma, centers largely around efforts to reduce emissions of nitrogen oxides (NOx), one of the main causes of ozone formation.

Ozone is formed under hot and sunny conditions when NOx (produced by power plants, cars, trucks and other sources) and volatile organic compounds (VOCs) undergo chemical reactions.

The MDE report says that Maryland’s more stringent requirements for coal-fired power plants were in effect during the summer of 2016 and significantly reduced emissions of nitrogen oxides (NOx) – effectively reducing 12 tons-per-day.

The report also notes that upwind NOx emissions from other states – Pennsylvania, West Virginia, Ohio, Indiana and Kentucky – contribute significantly to Maryland’s ozone problem.

In November, Maryland joined with other states submitting a petition requesting that the Environmental Protection Agency require upwind states to run their existing NOx controls effectively during ozone season.

Kelly said EIP supports Maryland’s participation in the petition but also calls for NOx emission reductions closer to home.

“The BRESCO incinerator in Baltimore emits more than 1,000 tons of NOx each year and emits more NOx per-unit-of-useful-output (energy plus steam) than any of the other large power plants in the state,” Kelly said, calling for “significant NOx reductions at this incinerator.”

Drone footage from 2015 shows Baltimore’s Wheelabrator incinerator (BRESCO) smokestack towering over the waterfront. (YouTube, Exploring with Purkz)

EIP, the Chesapeake Bay Foundation and other environmental groups have been engaging in MDE’s stakeholder process for setting new NOx emission limits for Maryland’s two incinerators.

Sulfur Dioxide Emissions

Also discussed in the report are sulfur dioxide (SO2) emissions which come from industrial processes and also cause respiratory problems.

The EPA identified two areas, in Baltimore and Anne Arundel counties, as not meeting new SO2 emission standards. The main sources of SO2 in these areas are the Brandon Shores, Herbert A. Wagner and C.P. Crane power plants.

Maryland sulfur dioxide concentrations dropping – and leveling off. (Maryland Department of the Environment)

MDE contends that its modeling is more accurate than EPA’s and that it shows the area in question meeting the new SO2 standards.

However, the agency says, “Maryland is being proactive to protect public health and has already begun to implement new control measures to further reduce SO2 emissions.”

Among them is a project, working with the local community and EPA, to install an SO2 monitor that will more accurately demonstrate whether there is an issue with SO2 in the area.