Fifteen to 20 demonstrators were seized, with officers using clubs and an irritant gas.

The changes in the men's lungs were 'consistent with the known effects of exposure to irritant gases', said the researchers.

Among weapons police confiscated from them were machetes, clubs, air pistols and vials of irritant gas.

The first salvos were irritant gas.

Coughing may be caused by air pollution including tobacco smoke, particulate matter, irritant gases, and dampness in a home.

Irritant gas exposures predominantly affect the airways, causing tracheitis, bronchitis, and bronchiolitis.

For example, people exposed to an irritant gas usually cough and have reddened eyes and irritation of other mucous membranes.

A common exposure involves accidental mixing of household ammonia with cleansers containing bleach; the irritant gas chloramine is released.

They also used relatively small amounts of the irritant gases chloromethyl chloroformate, chloropicrin, bromacetone and ethyl iodoacetate.

That change would better reflect the latest scientific understanding of the health risks posed by ozone, an irritant gas that is a main component of smog.

Chlorine, phosgene, sulfur dioxide, hydrogen chloride or sulfide, nitrogen dioxide, ozone, and ammonia are among the most important irritant gases.

Other important chemical causes of environmental diseases are the noxious gases which can be categorized as : Simple asphxiants, chemical asphyxiants, and irritant gases.

Manually operated, it fires all 40mm grenades, less-lethal and non-lethal ammunition, and tear/irritant gas projectiles; spent cartridges are ejected for easier reloading.

Depending on the type and amount of irritant gas inhaled, victims can experience symptoms ranging from minor respiratory discomfort to acute airway and lung injury and even death.

Irritant gases are those which, on inhalation, dissolve in the water of the respiratory tract mucosa and provoke an inflammatory response, usually from the release of acidic or alkaline radicals.

A common response cascade to a variety of irritant gases includes inflammation, edema and epithelial sloughing which, left untreated, can result in scar formation and pulmonary and airway remodeling.

The irritant gases are sulfur dioxide, ammonia, nitrogen dioxide, chlorine, phosgene, and fluorine and its compounds, which include luroine and hydrofluoric acid, fluorspar, fluorapatite, cryolite, and organic fluorine compounds.

The two American researchers say that, despite some of the workers having 20 years' experience in the electricity industry, none of the workers had heard of sulphur hexafluoride, nor did they know that their work could lead to exposure to irritant gases.

Manually operated, or it can only fire one at a time, it fires all 40 mm grenades, less-deadly and non-deadly ammunition (or what a gun fires), and tear/irritant gas capsules (the container in a liquid or gas is stored); spent ammunition is ejected for easier reloading.