Milnerton Lagoon gets air monitoring boost

Efforts to restore the Milnerton Lagoon and the surrounding environment have been strengthened with the installation of a new ambient air quality monitoring station, said the City.

The temporary station, currently located at the Woodbridge Island complex, has been operational since February 2025 and will be relocated to its permanent home at the Milnerton Canoe Club parking area by the end of July. 

Once in place, it will become the 14th station in the City’s air quality monitoring network, joining a broader initiative to improve transparency and public access to environmental data.

The station is equipped to continuously monitor ambient air for hydrogen sulphide, a colourless, flammable gas known for its pungent rotten egg smell. 

The City's mayoral committee member for Water and Sanitation, Zahid Badroodien said the gas, often described as a “nuisance odour,” can be found in sewer systems, the oil and gas industry, and certain industrial processes.

While unpleasant, hydrogen sulphide has only been detected in low concentrations so far, he said.

“We acknowledge the smell nuisance caused by H₂S (the gas), and the monitoring data confirms the community’s experience. This monitoring is part of the City’s broader efforts to protect public health and transparently share critical information with residents as we work to restore the environment at Milnerton Lagoon,” she said.

Although South Africa does not have a specific ambient air quality standard for hydrogen sulphide, the City is measuring results against World Health Organisation (WHO) guidelines, which set a 24-hour average limit of 150 micrograms.

To date, all levels recorded have remained well below this threshold, said Mr Badroodien.

The temporary station, functioning as a mobile mini-laboratory, captures air quality data every 10 to 15 seconds, with automated storage and analysis systems that compare readings against international health standards.

Findings from the first 100 days of data indicate that while odours may occur, there have been no exceedances of the WHO guideline, said Mr Badroodien.

Residents experiencing symptoms they believe may be related to air quality are encouraged to consult with healthcare professionals,” he said.

To improve public access to air quality data, the City is working with the national department of Forestry, Fisheries and the Environment, as well as the South African Weather Service, to publish real-time hydrogen sulphide readings via the South African air quality information system (SAAQIS).

Data will be accessible on the free SAAQIS app or via the website: www.saaqis.environment.gov.za