A method is described for cold-cutting a lamp having an inner pressure that is lower than the atmospheric pressure and containing a pollutant. The method includes keeping the lamp in position; cutting the lamp at at least one cutting point; prior to cutting, submerging the cutting point in a liquid or pasty composition; keeping the cutting point submerged during the cutting; and suctioning part of the composition into each cut-off portion. The composition is a dilatant and has a temperature no lower than the pour point thereof, prior to the cutting step. After the cutting, the temperature of the dilatant composition is reduced to a temperature lower than the pour point thereof, such as to increase the viscosity thereof and create a sealed stopper.