The smoking is water vapor, which is caused by the printing environment and paper status. When we do the printing, the fuser unit will heat the paper to around 180 °C, so during paper out of the printer, it would exchange its temperature with surrounding environment.
1, Print environment: when the temperature becomes much lower, the humidity will be much higher, so the vapor will get heavy. Due to the temperature difference and moist， the water vapor will produce accordingly. Usually, we suggest the printing temperature is 10-32℃, Humidity (RH) is 20%-80%, and it will work fine.
2, Paper status: the paper status when dry or moist will also influence strongly the printing vapor. When the paper is just unpacked to print , or just laid in the dry environment , there would be no or less vapor ; But when the paper is very moist , for example , it was exposed in 90% RH environment for a day , when printing , there will be more vapor coming out .
So, that is the cause of printing vapor, we must take care of the printing environment and the paper to avoid it.