Folks:
The information you need is found on a document known as a Materials Safety Data Sheet: there are several of them available for this compound, varying greatly in usefulness depending on their age. A summary follows:
NaN3 is a white, crystalline powder that is toxic and highly reactive.
It's pathways are by inhalation, ingestion and skin absorption.
It's LD50(Lethal Dose-50% of exposed population)is 27mg/kilo, or about .25 grams for a 200 lb person, when ingested. At higher dosages (1 or more grams) death occurs within 40 minutes(this is known from a suicide in Japan). There is no known antidote or effective treatment.
It's LD50 via inhalation or skin absorption is unknown: it is believed to be very fast acting if inhaled.
It's lethal mechanisms are manifold: it demylinatnes nerve tissue, binds with hemoglobin(blocking oxygen transport), and is extremely hypotensive(results in acute lowering of blood pressure)
When dissolved in water, it is odorless, colorless and tasteless.
If exposed to acids, it forms Hydrozoic acid, which is very toxic by inhalation.
If exposed to metals such as copper or lead, it forms highly explosive and unstable compounds(lead azide is used in detonators)
In auto air bags, it occurs as stacked tablets in a metal canister: the driver's side bag typically contains about 50mg and the passenger bag about 200mg.
This is nasty stuff: luckily, I know of no reason for anyone to pry open an unfired canister of this stuff, but if one did, you could do a lot of damage.