Due to recent volcanic activity in Iceland, it is expected that between tomorrow and Tuesday Madeira will have high levels of sulfur dioxide concentration in the atmosphere (above 1,500 meters).
It should be noted that this gas, in excess, can cause irritation of the eyes, nose and throat as well as respiratory problems.
Lower levels will not be affected by this , and sulfur dioxide cannot be seen, but will have a smell of sulfur maybe at the highest levels.