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During the first measurement campaign of the EU F<SMALL>ORMAT</SMALL> project in summer 2002 near Milan, northern Italy, ground-based scattered light differential optical absorption spectroscopy (DOAS) measurements were performed using a new multi-axis instrument. From the data set of this four week measurement period, the detailed analysis results of three days, 12&ndash;14 August, are presented exemplary. Slant column densities for formaldehyde (HCHO) and the oxygen dimer (O₄) have been retrieved, employing fitting windows from 335&nbsp;nm to 357&nbsp;nm and 350&nbsp;nm to 360&nbsp;nm respectively. In order to convert slant into vertical columns radiative transfer calculations were perfomred using aerosol parameters derived from the actual O₄ measurements. By analysing the measurements from different viewing directions (zenith, 4x&nbsp;off-axis) vertical profile information, and in particular mixing ratios for the boundary layer have been derived for the first time for HCHO with a multi-axis DOAS (MAX-DOAS) instrument. HCHO vertical columns are in the range of 5 to 20&middot;10¹⁵&nbsp;molec/cm² with an relative error of about 15%. This corresponds to HCHO mixing ratios in the boundary layer of 0.7&nbsp;ppb to 4.2&nbsp;ppb, which is in excellent agreement with simultaneous measurements from both a Hantzsch in-situ and a long-path DOAS instrument operated at the same place.