Infinitely less than in the past. The unpleasant odor traditionally associated with geothermal energy and thermal water is due to the hydrogen sulfide (H2S) underground. Nowadays, all power plants have an abatement system for hydrogen sulfide, which blocks around 99% of emissions thanks to its filters and containment technologies. The small remaining part can be released into the air by the cooling towers, and rarely passes the odor detection threshold for even the most sensitive noses (set at 4 micrograms per cubic meter). Larger concentrations are released only in case of exceptional circumstances and, even then, they still remain abundantly below the tolerable limit set by the World Health Organization (150 micrograms per cubic meter).