This photograph was taken on 4 February 2012 on Mohammed Mahmoud street near the junction with Mansour street in Downtown Cairo close to Egypt's Ministry of Interior during a protest against the perceived complicity of security forces in the death of Ahly football supporters.

Egypt's CSF or riot police used CS and possibly also CR gas and they were fired in a very heavy handed way with entire streets being enveloped. Also some CS gas stocks seemed to be carrying dates that suggested they had long outlived their "safer usage period."

I saw some protesters shaking violently on the ground as a result of prolonged tear gas exposure. Or possibly it was not tear gas according to a number of activists.

"“It burned the skin and lungs, and we all fell to the ground shaking uncontrollably" recalled Mahmoud Hassan - a marketing executive.

Commentators and medics argued as to whether the unusually severe symptoms of many protesters in Cairo were due to the deliberate use of alternate crowd control gases, the use of dangerously outdated stock or the overuse of tear gas in confined spaces.

( see for instance <a href="http://www.ipsnews.net/2011/12/deadly-gas-enters-the-arab-spring/" rel="nofollow">www.ipsnews.net/2011/12/deadly-gas-enters-the-arab-spring/</a> )

Much of the country's tear gas stocks were supplied from the United States, and despite their continued misuse against protesters Washington continued to supply the regime with this often lethal method of crowd control. However according to the Egypt Independent someone was eager to hide this fact from world attention.

A memorandum from Major General Magdy al-Gohary, head of Police Supply, admitted that -

"“The permit from the US government was obtained after removing the company’s name and country of origin written on the items." (Egypt Independent 22.02.13)

<a href="http://www.egyptindependent.com/news/egypt-imports-140000-teargas-canisters-us" rel="nofollow">www.egyptindependent.com/news/egypt-imports-140000-tearga...</a>

When I was briefly in detention in 2012 I remember feeling worried when during my first night at Abdeen police station - myself and a group of protesters who had been arrested and crammed into a small cage were guarded by teenage police cadets armed with tear gas rifles.

I was sad but not surprised when I read In 2013 that thirty seven prisoners died in agony asphyxiating on tear gas in a prison van.

“Of all the ways to die,” Foreign Policy reported, “this was one of the most horrible.” The lawyer for the prisoners later described how the mens' faces were so contorted and blue that witnesses thought they had been burned.

After a massive public outcry four police officers were later found guilty of involuntary manslaughter - the harshest sentence was a five year prison sentence while the other three officers got one year suspended sentences.