Studies were conducted to understand 2,3,7,8-tetrachlorodibenzo-p-diox
in (TCDD) behaviour in the near surface zone in relation to the operat
ing conditions: UV-intensity, temperature and exposure modes. Comparis
ons have been made between Oriel lamp exposure tests and sunlight expo
sure tests. Under Oriel lamp exposure, the convective transport of TCD
D, which depends on operating temperature, was the limiting factor in
the cleanup process. The product differences between Oriel exposure te
sts and sunlight exposure tests probably result from the difference of
UV-intensities.