Would you be comfortable with water purification that killed
90% of pathogens?

Edit- just noticed the claim is 98%. That is quite a bit better.

Since a bear has poor eyesight and good sense of smell, the
likely-hood of surprising a bear (when a grizzly is most likely
to attack) would be when you are facing the wind. Both sound
and smell would be muted by the airflow.

As for storing bear spray in a trunk, I have had soles of shoes
de-laminate from the heat generated by a car trunk. Not a good place to store something in an aerosol can.

Pepperspray works only to 32 F? Alaska doesn't get that cold
does it?

Limit yourself if you want, but the safety of other's children?

The Alaska NPS and USFS web pages I was going to post that suggested bringing more than 1 method of bear deterence have been changed. Both pages now have identical
wording. (They HAD listed air horns and flares as some of the other methods.)

"Protection

Firearms should never be used as an alternative to common-sense approaches to bear encounters. If you are inexperienced with a firearm in emergency situations, you are more likely to be injured by a gun than a bear. It is illegal to carry firearms in some of Alaska's national parks, so check before you go.

A .300-Magnum rifle or a 12-gauge shotgun with rifled slugs are appropriate weapons if you have to shoot a bear. Heavy handguns such as a .44-Magnum may be inadequate in emergency situations, especially in untrained hands.

State law allows a bear to be shot in self-defense if you did not provoke the attack and if there is no alternative, but the hide and skull must be salvaged and turned over to the authorities.

Defensive aerosol sprays which contain capsicum (red pepper extract) have been used with some success for protection against bears. These sprays may be effective at a range of 6-8 yards. If discharged upwind or in a vehicle, they can disable the user. Take appropriate precautions. If you carry a spray can, keep it handy and know how to use it."

http://www.nps.gov/anch/naturescience/bear-safety-in-alaska.htm

Here is the forest service employee manual on the subject

http://bit.ly/pQKwsa