Factors Associated with Persistent Lower Respiratory Symptoms or Asthma among Residents Exposed to a Sulphur Stockpile Fire Incident

Int J Environ Res Public Health. 2019 Feb 2;16(3):438. doi: 10.3390/ijerph16030438.


Introduction: Residents of Macassar, South Africa, were exposed to sulphur dioxide vapours (SO₂) caused by an ignited sulphur stockpile, which produced peak hourly SO₂ levels of 20⁻200 ppm. The aim of this study was to assess the risk factors associated with persistent lower respiratory symptoms (LRS) or asthma six years after acute exposure to high SO₂ levels. Methods: A case-control study of residents that presented for a health evaluation six years after the incident was conducted. Survey instruments included a questionnaire, clinical examination and medical record review by an expert panel. A "case" was defined as a resident with persistent LRS/asthma. The Industrial Source Complex Short Term Model (ISCST 3) was used to predict time-averaged hourly SO₂ levels. Results: A previous history of pulmonary tuberculosis (PTB) was associated with persistent LRS/asthma (ORudj: 3.49, CI: 1.46⁻8.35). Cases were more likely to report chest tightness (ORudj: 9.93; CI: 5.15⁻19.11) at the time of the incident. Peak exposure at hour 15 was associated with persistent LRS/asthma (ORadj: 1.04; CI: 1.01⁻1.07). Conclusion: LRS/asthma persisted in some individuals six years after acute SO₂ exposure. Aside from peak exposures, initial chest tightness and a previous history of PTB were the strong predictors of persistent LRS/asthma.

Keywords: asthma; exposure; persistent lower respiratory symptoms; sulphur dioxide.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Air Pollutants / toxicity
  • Asthma / epidemiology
  • Asthma / etiology*
  • Case-Control Studies
  • Female
  • Fires*
  • Humans
  • Inhalation Exposure / adverse effects*
  • Inhalation Exposure / statistics & numerical data
  • Male
  • Middle Aged
  • Respiration Disorders / epidemiology
  • Respiration Disorders / etiology*
  • Risk Factors
  • South Africa / epidemiology
  • Sulfur Dioxide / toxicity
  • Sulfur*
  • Surveys and Questionnaires


  • Air Pollutants
  • Sulfur Dioxide
  • Sulfur