Evaluation and Optimization of an Urban PM sub(2.5) Monitoring Network

The monitoring network established in the greater Cincinnati, OH, and northern Kentucky metropolitan area for measuring 24-h integrated particulate matter concentrations of 2.5 mu m aerodynamic diameter was evaluated. Data documented during 3 yr at 13 sites were analyzed for spatial and temporal variations. Both daily and hourly concentrations of particulates were marked by low spatial variations, due to a regional influence of secondary ammonium sulfate; trace element concentrations displayed high spatial variation. Seasonal variation accounted for 60% of the total temporal variation. The 13-site network can be optimized by reducing the number of measuring sites to eight.