First of all, be sure you’re in a well-ventilated area before spraying any of this stuff. It’s good for your shoes, not for your lungs (or pets, for that matter). Stand at a full arm's length distance, so your face will be as far away from the airborne spray as possible. Go in quick bursts, and ensure you cover each shoe/boot evenly. It’s not a bad idea to invest in a few disposable face masks just for this occasion, especially if you’re in less than ideal conditions and have to spray more often than you’d like. As an extra precaution, it is advisable to apply shoe protector spray outdoors.