they must be burning up in all that gear , lorie thought , though she had to admit the gas masks were sure to be more effective than the surgical masks , if only sven had a mask like that , then maybe he wouldnt now be ... as if the ground portion of the roadblock werent enough , two helicopters flew up and down on a perpendicular flight path to the road , probably ferreting out fugitives unfortunate enough to be on foot , or fugitive zombies even .