PBL heights from NCEP's NAM run of the WRF/NMM are compared with boundary layer heights estimated from radiosonde data. A critical Richardson number approach is used to estimate PBL heights from radiosonde data whereas the model uses a TKE scheme in boundary layer calculations. Differences between Ri number and TKE approaches are studied. Statistical parameters of PBL height verification are computed for different geographical regions as well as for individual stations. Boundary layer height is a key parameter in air quality modeling determining extent of turbulence and dispersion for pollutants. Related verification of ozone predictions from Air Quality Forecast System at NCEP is presented. Daily 1-hour and 8-hours averages, as well as daily peak ozone forecasts are compared with AIRNOW observations. Summer 2006 statistics are presented. PBL heights and ozone predictions are analyzed for high ozone episodes.