Residents across Karachi, particularly in coastal areas, report a foul smell after waking up to an unusual “fishy” or decaying odour. Officials and experts describe it as a natural marine process: microscopic algae, known as phytoplankton, decay and release a noticeable smell that can spread through the air.
Dawn reports that the phenomenon follows changes in sea conditions as the monsoon system ends in mid-September. Experts say phytoplankton, which are abundant during the monsoon and typically present in the upper parts of the sea, begin to decay afterward, producing odours that often dissipate in a few days. The Pakistan Meteorological Department and climate analysts cited additional atmospheric factors that affect how the smell moves. These include a low-pressure area off India’s Jamnagar that can circulate winds along Karachi’s coast and contribute to smog formation, which then helps the odour circulate across the city. The Express Tribune similarly attributes the smell to decomposing phytoplankton, noting the odour spreads citywide.
While the underlying cause is framed as natural, attention also turns to how weather and air pollution influence its intensity and distribution. In prior instances, health concerns have been discussed in relation to prolonged exposure to the combination of dusty air and odour, though no conclusive evidence is consistently cited.
