Many observers believe the Syrian government used a kind of toxic gas against opposition and civilians in recent weeks, and a senior White House official had evidence that the poison used was sarin gas, the Wall Street Journal reports. Syria was widely credited with having a large number of chemical weapons, including around 1,000 tons (907 metric tons) of nerve gases.
Responding to this threat, the demand for gas masks in Israel was increased dramatically in recent weeks – 62 percent of Tel Aviv residents now have a gas mask, according to the tower, while 75 percent of the residents of Kiryat Shmona (located near Israel- Syrian borders) had a Israeli civilian gas mask.
Depending on the type and construction, the gas mask can be effective on various substances, from ordinary dust and pollen to toxic gases – including nerve gas (such as sarin pesticides and organophosphates) that act on the central nervous system.
Cheap face masks, such as disposable paper filter masks available at hardware stores, are only effective against air particles. These masks are rated by the amount of particles they can filter: A mask rated 95 will stop 95 percent of airborne particles that are 0.3 microns in size and larger, while a mask rated 100 will filter out 99.97 percent of particles 0.3 microns and larger, making it comparable to a HEPA filter.