  The balloon-borne submillimeter instrument PRONAOS has observed one square
degree areas towards the Orion and M17 molecular clouds. The 2' - 3.5'
resolution maps obtained in four wide wavelength bands between 200 microns and
600 microns, exhibit the dust distribution in these regions. We analyze the
temperature and spectral index of the dust, and we show the anticorrelation
between these two parameters. We derive estimations of the ISM column densities
and masses in these regions.
