air, the human body and volcanoes

health impacts of volcanic emanations

Effects on health are mostly by inhalation. This also has impacts on skin and eyes.

Similar interactions of gases and airborne particulates from other sources

wildfires and desert dusts

Lung structure

Lungs hang free in the thoracic cavity, a bronchus connects each lung to the trachea

lungs and alveoli

Lungs contain millions of alveoli, the sites of gas exchange between air and blood

Each lung is covered by a

Pleural membrane

alveoli and blood

Each alveolus is about 200 micrometres in diameter and surrounded by pulmonary blood capillaries that are linked to the pulmonary arteries.

the epithelium 

one cell thick and comprises: 

• Type I pneumocytes which carry out gas exchange

• Type II pneumocytes which secrete surfactant to keep the inner surface moist 

oxygen and blood

Oxygen diffuses from the alveoli into red blood cells where it binds to haemoglobin.

Oxygen is taken through the pulmonary vein to the heart, pumped into the systemic vascular system and, finally taken to all the cells of the body.

Haemoglobin is a

Metalloprotein

haemoglobin

A haemoglobin molecule is a globular protein comprising a ring of four polypeptide subunits (2α and 2β chains).

An iron atom is at the centre of the haeme in each subunit. Each haeme can bind to one oxygen atom, so up to 4 oxygen atoms can be carried per molecule of haemoglobin.

air pollution occurring naturally in volcanic areas

• Lack of oxygen in the air due to an inert asphyxiant - usually carbon dioxide or rarely methane

• Another gas binds more strongly than oxygen to haemoglobin, becoming a noxious asphyxiant - usually hydrogen sulphide (H2S), sometimes carbon monoxide (CO)

• Another gas reacts with some parts of the respiratory system as an irritant gas, for example sulphur dioxide (SO2), hydrofluoric acid (HF) and hydrochloric acid (HCl).

or

Toxic volcanic metal vapour may be absorbed via inhalation - chronic exposure to mercury vapour causes neurological damage.

normal dry air

nitrogen (78.09%)

oxygen (20.95%)

argon (0.93%)

carbon dioxide (0.04%)

everything else (<0.01%)

volcanic gases

water, carbon dioxide, methane, carbon monoxide. hydrogen sulphide. sulphur dioxide. hydrochloric acid, hydrofluoric acid

Active and dormant volcanoes release gas by reduction of pressure on magma as it rises to, or near, the surface of the earth as:

1. Gases and vapours

2. Aerosols: droplets or particles suspended in a gaseous medium

3. Fumes: aerosols of solid particles, usually less than one micrometre in size, usually formed by escape of volatiles from molten materials

4. Smoke: volatile gases and particles, usually less than 05 micrometres in size, produced by combustion

volcanoes are not the same and differ in

• Total amount of gas released

• Proportions of different gases

• Duration of gas release

Composition of volcanic gas can vary at a single volcano over time. Gas emissions often continue long after eruptions.