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Maryland generally sees its warmest temperatures during the mid-summer months of July and August, and under normal conditions, rainfall peaks during these months. This is the time of year that Marylanders flock to beaches and mountains, enjoy local produce and seafood, and attend outdoor concerts and festivals. Enjoying our outdoor environment requires taking some precautions to prevent such discomforts as getting sunburned or overheated – using sunscreen, wearing lightweight clothing and drinking sufficient water are things we do to prevent discomfort.
Ozone Concentrations Driven by Heat, Pollution and Sunlight
Mid-summer is also when Maryland can experience high concentrations of the air pollutant ground-level ozone. In fact, MDE’s expert technical team monitors ozone pollution during the warmer months from May through September to protect public health. Ozone concentrations are driven by several factors, including meteorological conditions of warmer temperatures and intense sunlight. Ozone formation is a photochemical reaction between the various primary pollutants in the air and the temperatures and sunlight.
Ozone Formation
“The emissions from coal-fired power plants, cars and trucks and chemical products cook in the summer air and this creates sort of an air pollution soup,” says Tad Aburn, director of MDE’s Air and Radiation Management Administration.
Primary pollutants - or pollutants that come directly from sources such as smokestacks, vehicle tailpipes or chemical evaporation - come from various sources both locally and from sources far away. The primary pollutants that cause ozone formation are oxides of nitrogen (NOx) from burning fossil fuels, and volatile organic compounds (VOCs) from solvents, paints and gasoline. Maryland receives NOx pollution transported by winds from as far away as the Ohio River Valley and states in the South.
Ozone formation is strongly influenced by weather patterns and conditions. Long periods of dry weather and sunny conditions can lead to higher concentrations of ozone. Conversely, an extended period of above-average rainfall and cloud cover can keep ozone from reaching high concentrations. Breezy conditions can help disperse pollution, while stagnant air allows pollution to remain in an area.
Good Up High – Bad Nearby
Ozone pollution is a problem for several reasons. Ozone is the same chemical compound that exists several miles above the Earth’s surface (ozone layer), where it provides a benefit, and at ground level where it is harmful to human health and the environment. The layer of ozone in the stratosphere protects the Earth from ultraviolet rays from the sun. However, breathing ground level ozone can trigger health problems including throat irritation, coughing and chest pain. Ozone can worsen respiratory illnesses, such as asthma and bronchitis – and long-term exposure can cause premature aging of lung tissue.
Many plants are sensitive to and suffer from exposure to ozone. The health and appearance of urban vegetation and trees in national parks is diminished and crop yields are reduced by ozone.
Coughing Carburetors Unhealthy for Humans
“Maryland now controls emissions locally from smokestacks to perfumes,” explains Aburn. “So the trend has been that our air quality is improving. Locally, Maryland’s biggest source of emissions is from vehicles. As older cars and trucks are replaced, local emissions will be reduced even more.”
“A look at the ozone data over the past 26 years does indeed support the claim of locally improving air quality,” according to Michael Woodman, a meteorologist with MDE’s Ambient Air Monitoring Program. “During the 1980’s and 1990’s there were an average of 52 and 42 8-hour ozone exceedance days per year, respectively. Thus far between 2000 – 2006 there have been an average of 23 8-hour ozone exceedance days per year.”
The continued trend of the decreasing number of days when Maryland experiences “Bad Air” indicates that the state is headed in the right direction of improving air quality for its citizens.
Preventive Actions for Ozone Reactions
In addition to Maryland Department of the Environment’s efforts to improve air quality and reduce pollution, there are several actions that individuals, families and businesses can take to help. First, individuals can check real-time air quality and forecasts Air Quality Index or AQI on the Internet, by calling the air quality hotline at 410-537-3247, or on the weather page of the local newspaper. If you are an individual especially sensitive to pollutants, plan to reduce your exposure to outdoor air when levels reach the Unhealthy for Sensitive Groups range. You may also check the AQI to determine whether outdoor conditions are good for strenuous exercise or prolonged heavy physical work.
Other actions include keeping vehicles well maintained, reducing vehicle idling, using public transit, walking and conserving electricity. Click here for more information about MDE’s Air programs. |
