The tear gas canisters used on protesters during the “Anger” demonstrations Friday had surpassed their 2008 expiration date, according to investigations by Al-Masry Al-Youm.

Al-Masry Al-Youm reporters managed to collect canisters off Cairo's streets. The US-made tear gas canisters bear manufacture dates of 2003 with an indication that they expire after five years.

The canisters, expired over two years ago, were used heavily across Cairo in clashes between the protesters and police forces. Tear gas was seen covering multiple demonstrations sites, especially in downtown Cairo areas such as Tahrir square, Galaa Bridge, Qasr al-Nil Bridge and 6 October Bridge. In many instances during the protests, protesters were seen throwing the gas-emitting canisters back at security forces or into the Nile river.

While tear gas’ effects are usually limited to skin and eye irritations, its use may sometimes lead to suffocation. Some experts contend that expired tear gas may lead to more dangerous health effects--than its non-expired counterpart--for people heavily exposed to it.

Demonstrations in Egypt’s streets continued Friday evening despite a curfew that was declared to be force from 6PM and is set to end at 7AM the next day. The number of people in the streets appeared to have declined as the evening progressed after 8PM.