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Assessing Outdoor Air Near Schools

The Ohio Valley Educational Service Center - Marietta, OH

EPA selected this school for monitoring because it is located near at least one large industry that is a source of air toxics emissions. The pollutants monitored were different from school to school. Based on emissions from nearby sources, EPA identified key pollutants to measure in the air near this school. We reported concentrations of those key pollutants in the table below. Concentrations for other toxic air pollutants collected at the site are also available (PDF) (1p, 63k). (For example, manganese may be the key pollutant at a monitoring site but other metals, such as arsenic,  measured in the sample also are available.)  

About the Data
The table below shows the levels of key pollutants in air samples collected at the monitoring site beginning in August 2009.   The table also includes individual “sample screening levels” for each key pollutant monitored at the school.  EPA developed these screening levels to help the Agency and the community get an early sense of what the data were showing. The sample screening level is a level of pollution in the air that is below what we expect to cause health problems from short-term exposures – all day, every day over a period ranging up to at least a couple of weeks (longer, for some pollutants).

About The Table

Compare the sample results to the short-term screening level at the top of the table. Numbers at or below that level indicate the pollutant is not likely to pose immediate health concerns.

To use the screening level, compare it to each sample result:

  • a sample result at or below the sample screening level is not a concern for risk of health problems from short-term exposures.
  • a sample result above the screening level does not mean that there is a risk to children and adults at the school.  It is a signal for EPA to further evaluate those and subsequent results for that pollutant. 

After monitoring was completed, EPA analyzed the potential for health concerns from long-term exposure. This analysis can be found under the Initial Analysis tab. Monitoring results are in the table below.

Sample Results
Key Pollutants Lead Non-FRM/FEM
(Nanograms/cubic meter)
(Nanograms/cubic meter)
Sample Screening Level 150 500
08/17/2009 -- 43.7
08/23/2009 -- 4.15
08/29/2009 1.68 54.1
09/04/2009 5.16 --
09/10/2009 4.31 --
09/16/2009 4.13 12.3
09/22/2009 1.95 3.59
09/28/2009 1.21 14.4
10/04/2009 1.79 12.3
10/10/2009 2.34 --
10/16/2009 2.46 7.40
10/22/2009 12.2 373
10/28/2009 2.87 94.2
11/03/2009 6.47 438
11/15/2009 11.4 238

–– = Sample not taken or invalid

Also monitored (PDF) (1p, 63k)

To further evaluate sample results above a screening level, we considered:

  • information about the chemical and its health impacts,
  • information about collection of the sample (e.g., weather, activities around the monitor)
  • potential sources of the pollutant, and 
  • the pattern of levels across multiple samples within the monitoring period. 

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