Make sure to keep windows closed, doors sealed and any other entry point closed off. These are great areas to install gluetraps . Use several around entry points and doorways. These will help to collect spiders and other perimeter invaders as they enter your structure. They will avoid it and relocate or die if they persist in treated areas.
Cobweb eliminator seems to discourage web reformation as well.
Use it as needed. This may be once a week, once a month or once a quarter. Generally, after a few treatments, spider activity will decrease dramatically which reduces the amount of treating needed. Dust wall voids if there are a lot of spiders entering from outside. Once applied in the wall void, there will be no chance of exposure to those in the room and even if an exposure occurred, the chance of any impact is pratically non-existent.