Although it's possible that RF is triggering the alarms, I think it's
highly unlikely in this case for the following reasons:

1. Battery operated alarms are physically small, so they make very poor
receiving antennas. That inherently makes them pretty immune to RF.

2. Although it's possible that one particular design might be
particularly sensitive, it's unlikely that several quite different ones
would be equally sensitive.

3. Typical amateur operating habits usually involve a comparatively long
period of operation at one frequency and direction. A few chirps per day
doesn't fit this pattern.

So I think you're looking in the wrong place for the problem. But I sure
don't know where you should be looking. I've had an ionization alarm
trigger from such things as steam from a nearby bathroom when someone
takes a shower, but I'd be surprised if it would get thick enough to
trigger a photoelectric alarm, or widespread enough to trigger multiple
alarms. But there are probably some resources on the web which can help
you sort it out. Good luck!

Roy Lewallen, W7EL