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2014 Mecklenburg County State of the Environment Report

Nitrogen Oxides (NOx), Sulfur Dioxide (SO2), Carbon Monoxide (CO) and Lead

Air Quality indicatorMecklenburg County is in attainment with the NO2, SO2 and CO National Ambient Air Quality Standards. Mecklenburg County began lead (Pb) monitoring in 2011. 

Air Quality Nitrogen Dioxide, Sulfur Dioxide and CO Index 

Nitrogen Oxide (NOx)
Nitrogen dioxide (NO2) is one of a group of highly reactive gases known as nitrogen oxides (NO2). While the Environmental Protection Agency's National Ambient Air Quality Standards (NAAQS) covers the entire NOx group, NO2 is the component of greatest interest and the indicator for the larger group of nitrogen oxides. NO2 forms quickly from emissions from cars, trucks and buses, fossil fuel-fired power plants and off-road equipment. NO2 is a key precursor to ozone formation.

The NAAQS for NO2 is a primary 1-hour standard of 100 parts per billion (ppb) and an annual standard of 53 ppb.  Mecklenburg County meets the current NO2 standards.

Sulfur Dioxide (SO2)
Sulfur dioxide (SO2) is one of a group of highly reactive gases known as "oxides of sulfur." It is produced from the burning of fossil fuels (coal and oil) and the smelting of mineral ores (aluminum, copper, zinc, lead and iron) that contain sulfur.

The NAAQS for SO2 is a 1-hour standard of 75 ppb and a 3-hour standard of 0.5 ppm.  Mecklenburg County meets the current SO2 standards.

Carbon Monoxide (CO)
Carbon Monoxide (CO) is a colorless, odorless gas that is formed when carbon in fuel is not burned completely. CO is a component of motor vehicle exhaust. Higher levels of CO generally occur in areas with heavy traffic congestion. In Mecklenburg County, the majority of all CO emissions come from motor vehicle exhaust.

The NAAQS for CO consist of a primary 8-hour standard at 9 ppm and a 1-hour primary standard at 35 ppm. Mecklenburg County meets the current CO standards.

Lead is a metal found naturally in the environment as well as in manufactured products. The highest levels of lead concentrations are usually found near lead smelters. Other stationary sources that produce lead emissions are waste incinerators, utilities and lead-acid battery manufacturers. With almost no known lead sources, Mecklenburg County has not routinely conducted lead monitoring. On December 14, 2010, EPA revised the ambient monitoring requirements for lead which resulted in MCAQ implementing a lead monitoring network in 2011 to determine compliance with the revised NAAQS.
The NAAQS for lead (Pb) is a rolling 3 month average of 0.15 µg/m3.  The compliance value for the rolling three month average of Pb is 0.003 µg/m3. Lead is not shown in the graph as there is only one data point for 2012.  Mecklenburg County meets the current lead standard.  
What does this mean for my health?
The amount of air pollution that is measured is compared to a health-based National Ambient Air Quality Standard (NAAQS) and converted into an Air Quality Index (AQI) value.  This AQI value can range from 0-300 and communicates the amount of air pollution that is measured and how that affects our health.  When the AQI value is less than 50, the air quality is considered satisfactory by the EPA and is expected to pose little or no health risk.  The AQI value for each pollutant shown in the graph above (NOx, SO2, and CO) is less than 50 and is considered good.  Read more about the Air Quality Index and how it relates air pollution to your health.

For more information on this topic, see the links below or visit "Contact Us" on the MCAQ site. 

What you can do to reduce air pollution in Mecklenburg County.

More Information:
•  Mecklenburg County Air Quality - Criteria Pollutants
•  Stationary Sources
•  Mobile Sources
•  Area Sources
•  Health Effects of Air Pollution

•  EPA - NOx Overview 
•  Health Effects of Nitrogen Oxides

•  NCDENR - Sulfur Dioxide
•  Health Effects of Sulfur Dioxide

•  EPA - Mobile Sources - Carbon Monoxide 
•  Health Effects of Carbon Monoxide

•  EPA - Lead Standards
•  Health Effects of Lead in Air

Return to Air Quality Chapter Page

The trends shown in the State of the Environment Report are not all based on tests of statistical significance. Data analysis, anecdotal evidence, and best professional judgment have been compiled to represent these trends. The State of the Environment Report takes a snapshot of important environmental indicators in an effort to educate the public while highlighting challenges, successes and the general direction of change for each indicator. For additional information on these indicators and the determination of trends, please follow the links and feel free to contact the appropriate resources.

Last updated 2/24/14