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Air Quality

Air Pollutants - Particulate Matter (PM) - Forecasting and Monitoring

Historical PM Monitoring Data and Trends

Over the last 10 years, the PM2.5 monitoring network has recorded a decline in PM2.5 levels due to improvements in air quality. On average, the statewide daily concentrations have decreased 32% from 2001 to 2010 while the annual concentrations have decreased 28% over the same time period. However, as scientists gain a better understanding of the health and environmental effects of PM2.5, there is a possibility that the EPA will lower the PM2.5 standard. Therefore, cooperative efforts will need to be continued to ensure that South Carolina meets any current and future PM2.5 National Ambient Air Quality Standards (NAAQS).

PM2.5 Design Values

Every year, an annual design value and a 24-hour design value are calculated for each monitoring site and compared to the NAAQS. The annual design value for PM2.5 is the average of the three arithmetic means of the previous three years including that year. For example, a monitoring site's annual design value for 2010 is the average of the arithmetic means from 2008, 2009 and 2010. The 24-hour design value for PM2.5 is the average of the three 98th percentiles of the three previous years including that year. For example, a monitoring site's 24-hour design value for 2010 is the average of the 98th percentiles from 2008, 2009 and 2010. See the annual and 24-hour design values of South Carolina over the last 10 years below.

Statewide PM2.5 Design Value Trends (2000 - 2009)

In the charts below, the blue band shows the range and trend of average South Carolina PM2.5 design values (annual and 24-hour) over a ten-year period. All PM2.5 monitoring data between 2001 and 2010 are included in the charts. Eighty percent of the monitoring sites have design values within the blue band. The middle white line is the state's average PM2.5 design values by year.

Variability of PM2.5 Annual Design Values across South Carolina
(based on 2006 PM2.5 NAAQS)

Statewide PM2.5 Annual Design Value Trends (2001 - 2010)

Variability of PM2.5 24-Hour Design Values across South Carolina
(based on 2006 PM2.5 NAAQS)

Statewide PM2.5 24-hour Design Value Trends (2001 - 2010)

During the last ten years, PM10 concentrations have remained relatively unchanged. Historically, PM10 levels have been well below the 2006 NAAQS.

PM10 Design Values

Every year, a design value is calculated for each monitoring site and compared to the National Ambient Air Quality Standard. The PM10 NAAQS is an exceedance-based standard with a 24-hour averaging time and 150 micrograms per cubic meter (g/m3) level. The NAAQS level is not to be exceeded more than once per year on average over three years.

Statewide PM10 Design Value Trends (2001 - 2010)

In the chart below, the blue band shows the range and trend of average South Carolina PM10 design values over a ten-year period. All PM10 monitoring data between 2001 and 2010 are included in the chart. Eighty percent of the monitoring sites have design values within the blue band. The middle white line is the state's average PM10 design values by year.

Variability of PM10 2nd Maximum Annual Design Values across South Carolina
(based on 2006 PM10 NAAQS)

Statewide PM10 Design Value Trends (2001 - 2010)

For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.