Editing Smoke screen (section)

==Chemicals used==
<!-- Abbreviated from FM 8-9 part III. Should be somewhat mixed with the content above. -->[[File:US Navy 100915-N-4894D-110 Marines participate in the 60th anniversary of teh Incheon Landing Operation.jpg|thumb|upright=1.2|Amphibious vehicles deploying smoke grenades]]

===Zinc chloride===
Zinc chloride smoke is grey-white and consists of tiny particles of [[zinc chloride]]. The most common mixture for generating these is a [[smoke composition|zinc chloride smoke mixture]] (HC), consisting of [[hexachloroethane]], grained [[aluminium]] and [[zinc oxide]]. The smoke consists of zinc chloride, zinc oxychlorides, and [[hydrochloric acid]], which absorb the [[humidity|moisture]] in the air. The smoke also contains traces of organic chlorinated compounds, [[phosgene]], [[carbon monoxide]], and [[chlorine]].

Its toxicity is caused mainly by the content of strongly acidic hydrochloric acid, but also due to thermal effects of reaction of zinc chloride with water. These effects cause [[lesion]]s of the [[mucous membrane]]s of the upper airways. Damage of the lower airways can manifest itself later as well, due to fine particles of zinc chloride and traces of phosgene. In high concentrations the smoke can be very dangerous when inhaled. Symptoms include [[dyspnea]], retrosternal pain, [[hoarseness]], [[stridor]], [[lachrymation]], [[cough]], [[expectoration]], and in some cases [[haemoptysis]]. Delayed [[pulmonary edema]], [[cyanosis]] or [[bronchopneumonia]] may develop. The smoke and the spent canisters contain suspected [[carcinogen]]s.

The prognosis for the casualties depends on the degree of the pulmonary damage. All exposed individuals should be kept under observation for 8 hours. Most affected individuals recover within several days, with some symptoms persisting for up to 1–2 weeks. Severe cases can suffer of reduced pulmonary function for some months, the worst cases developing marked dyspnoea and cyanosis leading to death.

Respirators are required for people coming into contact with the zinc chloride smoke.

===Chlorosulfuric acid===
[[Chlorosulfuric acid]] (CSA) is a heavy, strongly acidic liquid. When dispensed in air, it readily absorbs moisture and forms dense white fog of [[hydrochloric acid]] and [[sulfuric acid]]. In moderate concentrations it is highly irritating to eyes, nose, and skin.

When chlorosulfuric acid comes in contact with water, a strong [[exothermic]] reaction scatters the corrosive mixture in all directions. CSA is highly corrosive, so careful handling is required.

Low concentrations cause prickling sensations on the skin, but high concentrations or prolonged exposure to field concentrations can cause severe irritation of the eyes, skin, and respiratory tract, and mild cough and moderate [[contact dermatitis]] can result. Liquid CSA causes [[acid burn]]s of skin and exposure of eyes can lead to severe eye damage.

Affected body parts should be washed with water and then with [[sodium bicarbonate]] solution. The burns are then treated like thermal burns. The skin burns heal readily, while cornea burns can result in residual scarring.

Respirators are required for any concentrations sufficient to cause any coughing, irritation of the eyes or prickling of the skin.

===Titanium tetrachloride===
[[Titanium tetrachloride]] (FM) is a colorless, non-flammable, corrosive liquid. In contact with damp air it hydrolyzes readily, resulting in a dense white smoke consisting of droplets of hydrochloric acid and particles of titanium oxychloride.

The titanium tetrachloride smoke is an irritant and unpleasant to breathe.

It is dispensed from aircraft to create vertical smoke curtains, and during World War II it was a favorite smoke generation agent on warships.

Goggles and a respirator should be worn when in contact with the smoke, full protective clothing should be worn when handling liquid FM. In direct contact with skin or eyes, liquid FM causes acid burns.

===Phosphorus===
{{Main|White phosphorus (weapon)}}
Red [[phosphorus]] and [[white phosphorus incendiary|white phosphorus]] (WP) are red or waxy yellow or white substances. White phosphorus is [[Pyrophoricity|pyrophoric]] - can be handled safely when under water, but in contact with air it spontaneously ignites. It is used as an [[Incendiary device|incendiary]]. Both types of phosphorus are used for smoke generation, mostly in artillery shells, bombs, and grenades. <!-- effects of exposure? -->

White phosphorus smoke is typically very hot and may cause burns on contact. Red phosphorus is less reactive, does not ignite spontaneously, and its smoke does not cause thermal burns - for this reason it is safer to handle, but cannot be used so easily as an incendiary.

Aerosol of burning phosphorus particles is an effective obscurant against [[thermal imaging]] systems. However, this effect is short-lived. After the phosphorus particles fully burn, the smoke reverts from emission to absorption. While very effective in the visible spectrum, cool phosphorus smoke has only low absorption and scattering in infrared wavelengths. Additives in the smoke that involve this part of the spectrum may be visible to thermal imagers or IR viewers.<ref name="yarchive.net">{{cite web|url=http://yarchive.net/mil/infrared_smoke.html|title=Infrared smoke (Arno Hahma)|website=yarchive.net}}</ref>

===Dyes===
{{Main|Colored smoke}}
[[File:Smoke Signal 1.jpeg|thumb|Yellow smoke screens deployed to mark soldiers completing an objective during [[Exercise Northern Edge]] 2017]]
Various signalling purposes require the use of [[colored smoke]]. The smoke created is a fine mist of dye particles, generated by burning a mixture of one or more dyes with a low-temperature [[pyrotechnic composition]], usually based on [[potassium chlorate]] and [[lactose]] (also known as milk sugar).

Colored smoke screen is also possible by adding a colored dye into the fog oil mixture. Typical white smoke screen uses titanium dioxide (or other white pigment), but other colors are possible by replacing titanium dioxide with another pigment. When the hot fog oil condenses on contact with air, the pigment particles are suspended along with the oil vapor. Early smoke screen experiments attempted the use of colored pigment, but found that titanium dioxide was the most light scattering particle known and therefore best for use in obscuring troops and naval vessels. Colored smoke became primarily used for signaling rather than obscuring. In today's {{When|date=December 2019}} military, smoke grenades are found to be non-cancer causing, unlike the 1950s AN-M8 model.

===Sulfonic acid===
The smoke generator on the [[Medium Mark B]] tank used [[sulfonic acid]].<ref name=foss30>{{Cite book|title=The Vickers Tanks From landships to Challenger |last=Foss |first=Christopher F |author2=McKenzie, Peter  |year=1988 |publisher=Patrick Stephens Limited |isbn=1-85260-141-8 |page=30 }}</ref>