Our Beautiful World
Foto: K.A. McGee on 19 September 1995
Svoveldioksid og andre vulkanske gasser stiger opp fra Pu`u `O`o åpningen på Kilauea vulkanen, Hawai`i. Under utbrudd i perioden mellom 1986 og 2000, slapp Kilauea ut fra 2.000 til 1.000 tonn irriterende svoveldioksid (SO²) hver dag.
Carbon Dioxide (CO2) is a colorless, odorless, non flammable, heavier than air, and toxic gas
only at high concentrations.
With respect to toxicology, CO2 is not toxic at low concentrations. Concentrations from 3 to
5 % accelerate the breathing rhythm. Repeated exposures provokes headaches without chronic
injurious effects. Concentrations from 8 to 15 % induce headache, vertigo, vomiting, fainting
and possibly death if the patient is not oxygenated immediately. Higher concentrations quickly
induce circulatory shortage followed by coma and death. The maximum permissible
concentration recommended by hygienists is 5,000 ppm, or 9,000 mg.m3.
Carbon dioxide is necessary for photosynthesis, which is enhanced at high concentrations.
The atmosphere, however, needs containing in the same time enough oxygen to allow
In dry gases (global gas minus water), CO2 varies between 20 and 95 %. In plumes,
concentrations may be very high close to their emission vents (high concentrations 40 m above
a lava fountain at Niragongo, Tanzania). In this case, CO2 concentrations did not exceed at
7 km from the vent the maximum permissible concentration (9,000 mg.m3). If the gases are
emitted slowly, CO2 flows downslope and asphyxiation of men and animals may be fulminent.
Such events, however, need storage conditions of CO2 in the ground or in crater lakes close
to the Dieng or Lake Nyos cases.
More about CO2 - click here
|Photo glossary of volcano terms: Volcanic gas|