Dust emissivity I_ν/N_{H i} as a function of ecliptic latitude for 3000 GHz (lower left), 857 GHz (lower right), 545 GHz (upper left) and 353 GHz (upper right). Each point gives the average and standard deviation (error bar) of all pixels in the corresponding bin in ecliptic latitude (IRIS error bars omitted for clarity). These plots were obtained using data smoothed to 1° and selecting pixels with N_{H i}< 3 × 10²⁰ cm^-2.