The active ingredients of the flea sprays are not known to be associated with asthma in any way. However, if you have personally experienced issues with aerosol sprays then you can ask other family members to use the spray in your absence. After spraying it, one should ideally open all the windows immediately to ensure proper ventilation. The spray mist should settle down before you allow anyone to enter. You should also read the label before you use the spray, so that you can adhere to the safety advice.