Air Quality Monitoring in the DMA
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The air we breathe comprises of a cocktail of many chemicals, some of which are of human origin, and others which occur naturally in most natural environments. The pollutants most commonly measured in the air, so called 'criteria pollutants', are sulphur dioxide, nitrogen oxides, carbon monoxide, particulate matter, volatile organic compounds, ozone and lead.

Sulphur Dioxide (SO2)

  • Sulphur dioxide is the most extensively monitored air pollutant in the Durban Metropolitan Area (DMA).
  • CSIR-devised 'bubblers' have been used for many years on a national basis and at several sites in Durban. They measure SO2 over two to three day intervals. Results from this ongoing survey are used to evaluate seasonal and long term trends , to identify potential SO2 'hot spot' areas and to measure compliance with air quality guidelines.
  • A metropolitan wide 'broad sweep' SO2 survey at 90 sites is also currently underway using new passive sampler technology.
  • The Steering Committee of the Durban South SO2 Management System has a more sophisticated on line SO2 monitoring network in the Durban South Basin. From one or two previously poorly managed continuous SO2 monitoring stations, this network has expanded significantly and now comprises an on-line computerised dispersion model, 4 permanent and 1 mobile continuous SO2 monitoring stations, and 4 meteorological stations which are all professionionally managed and calibrated. The monitoring system was recently accredited and awarded the National Laboratories Association's prestigious ISO Guide 25 quality certificate to ensure data integrity, and is the first monitoring system in South Africa to qualify for this certificate.
  • Click here to view a graph of the typical annual cycle of SO2 concentration in in the air.

Black Smoke

  • Black smoke, also referred to as Soiling Index, is measured over two to three day periods using the same 'bubbler' apparatus as used for SO2 monitoring.
  • Smoke data is used to evaluate seasonal and long term trends, and to identify potential 'hot spot' areas. Since smoke levels are measured as an index, compliance with air quality guideline concentrations cannot be evaluated directly.
  • The expansion of smoke monitoring is not envisaged as internationally the trend is towards health related fine suspended particulate measurements (PM10).
  • Click here to view long term trends in smoke results and here to view the typical annual cycle of smoke in air.

Ozone (O3)

  • Ozone measurements in the DMA have historically been conducted on a sporadic basis. While some of the O3 monitoring data may be regarded as acceptable, much of it is invalid in terms of existing quality assurance requirements and is stored only in hard copy formats. Click here to view a typical daily cycle of Ozone in the air
  • A metropolitan wide 'broad sweep' O3 survey at 90 sites is currently underway using new passive sampler technology.
  • The Steering Committee of the Durban South SO2 Management System has a more sophisticated on-line O3 analyser at Wentworth.


SO2 and O3 Analyser

Lead (Pb)

  • Lead measurements have for many years been carried out at the Durban City Hall over monthly sampling periods as part of a national lead survey of all major cities in South Africa.
  • Click here to view long term trends and and typical annual cycle of lead levels.
  • A metropolitan wide 'broad sweep' survey of suspended particulates at 90 sites is currently underway, for which lead concentrations will be determined.

Volatile Organic Compounds (VOCs)

  • Due to the complex variety of VOCs in the air, and the expense of VOC analyses, very few monitoring surveys have been performed in Durban by the CSIR on behalf of the Department of Environmental Affairs and Tourism.
  • Click to view graph 

Oxides of Nitrogen (NOx)

  • The DMA currently has very little information on concentrations of nitrogen oxides in the air.
  • Click here to view graph
  • A metropolitan wide 'broad sweep' nitrogen dioxide survey at 90 sites is currently underway using new passive sampler technology.
  • The Steering Committee of the Durban South SO2 Management System has a more sophisticated on-line NOx analyser at Wentworth.


Typical Air Quality Monitoring Station


PM10 Sampler (Note new and used filter paper)

Particulate Matter (PM)

  • Measurements of particulate matter in the air have been performed at several sites on an intermittent basis, hence long term trends are difficult to evaluate.
  • In addition to lead (Pb), some other metals in PM samples have also been determined.
  • A metropolitan wide 'broad sweep' total suspended PM survey at 90 sites is currently underway using gravimetric filter methods. Metal content in these particulate samples will be determined.
  • The Steering Committee of the Durban South SO2 Management System has a continuous PM monitor at Wentworth.
  • PM10 surveys are performed in the Coedmore and Ridgeview Quarry areas for a few weeks every year and no measurements for PM2.5 have been conducted in the DMA.

Dust Fallout

  • Measurements of this nuisance related to dust fallout have typically been conducted to verify complaints and quantify the degree of nuisance at specific sites.
  • This monitoring has progressed slightly in that more formalised monitoring surveys are now performed for some industrial processes on a polluter pays basis.

Carbon Monoxide (CO)

  • No information is currently available on carbon monoxide levels in the DMA.

Pollen

  • A once off pollen survey was conducted by Wits University over the period October 1997 to April 1998 at five sites. The results of this survey are available here.
  • A pollen monitor has been installed at Wentworth.


"Burkard 7 day recording volumetric spore trap", or more simply a "pollen sampler"



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Last update: October 1999