What is that smell? Mystery rotten-egg stench triggers health concerns across Gauteng

A perplexing rotten-egg odor has permeated sections of Gauteng, prompting health worries and widespread inquiries. Residents from regions such as Randfontein, Krugersdorp, Muldersdrift, Fourways, and various parts of Johannesburg reported the noxious smell, which took on various descriptions including sulfur, gas, cat urine, sewage, and even engine oil. Initially, some residents suspected their pets or their homes before realizing the odor was affecting entire neighborhoods.

BCI Security, a security and risk intelligence firm, reported that residents across parts of Johannesburg had complained about a strong sulphurous or rotten-egg smell, although the source remained unverified. The company highlighted that such odors have previously been linked to hydrogen sulphide (H₂S), a gas capable of causing eye and respiratory irritation, headaches, dizziness, nausea, and breathing difficulties depending on exposure levels.

In response, residents were advised to limit outdoor time, keep windows and doors closed if the smell entered their homes, and consult medical professionals if they experienced significant irritation or persistent breathing issues. The Gauteng Weather forecast indicated that east-south-easterly winds on October 28 contributed to the strong sulphur smell across the province, leading to unhealthy air-quality conditions for sensitive groups in certain areas.

The Mogale City Local Municipality received numerous complaints from residents and stakeholders in and around Krugersdorp, as reported by the Roodepoort Record. Air-quality monitoring at the Krugersdorp Central Library detected elevated PM2.5 and PM10 levels early in the morning, which declined later in the day. These readings were reviewed and showed spikes in particulate matter between midnight and 8 AM on Wednesday, followed by a decrease after 8 AM.

Despite the complaints, the origin of the smell remains a mystery. The Municipality stated that due to the transboundary nature of the issue, they would engage relevant authorities, as the matter is regional in scope. The Midvaal Local Municipality is also investigating recurring reports of ammonia-, sulphur-, and rotten-egg-like odors in its area, as part of a broader inquiry into odour incidents affecting parts of Gauteng and Mpumalanga.

For now, residents continue to grapple with unanswered questions as authorities endeavor to uncover the cause of this unusual smell plaguing parts of the province.