Instrumentation and procedures for the synthetic production of photochemical aerosols within a laminar airflow along a tubular channel are described. Special micro-dosimetry quantitatively facilitates continuous addition of reactive trace components (hydrocarbons, NO, NO2, SO2) and of defined nucleating particulates. The flow is subsequently irradiated symmetrically in the spectral range (320-450 mμ) in a special channel section without temperature increase, at adjustable intensity levels and exposure durations up to several times solar intensity at ground level. The resulting aerocolloidal components are analyzed with the Aerosol Spectrometer for determining the size and mass distribution of the photoactivated particulates at various reaction stages. Examples of smog-type reactions between traces of NO2 and olefines, and of modifications of natural aerosols, are presented.