Sulphide dust explosions in mines. Sulphur dioxide exposure - similarities and differences in effects on lungs

Introduction
Sulphide dust explosions with high levels of sulphur dioxide may be a problem in rich sulphide ores. Accidentally high levels of sulphur dioxide also have occurred in paper mills, cellulose industry, foundries etc. Fatal accidents and accidents with lung damage have been described since the early twenties in the USA. Long-term effects differ and the clinical significance of sulpur dioxide exposure is debated.

Methods
We have described the results of two sulphide dust explosions in the mining industry in Norway, in 1968 and 1989, involving 6 workers. Mineworkers are systematically examined by the companies SHE service, with spirometric tests, medical examinations, chest x rays etc. Result from medical examinations both pre accidental and thereafter for more than 20 years are given.

Results
Examples of exposure levels are given as well as conditions for the highest risk of sulphide dust explosion. The most commen preventive actions are described as well as safety precautions. One of the miners died in the accident, two survived without serious lung damage, three developed chronic obstructive lung disease, ranging from light COPD to lung failure. Reduction in lung function developed fast and deteriorated during the following days and weeks. Airways were initially described as highly reactive. Impairment may be chronic, is mainly obstructive and changes seem to be located in the peripheral airways.

Discussion
Sulphur dioxide represents a challenge for many workers and their SHE organisation. Sulphur dioxide exposure may end up i serious lung disease. Other reports also support these findings. We have reason to believe that the outcome is dependent on the degree of exposure. Exposure levels and the effects on the lungs are however impossible to foresee. Workers involved should receive immediate hospital treatment and careful medical follow up.