It is always best to use caution. You did a great job to contact your Grandma and bring it to the attention of your Dad. Like the other posters said - you probably saved the lives of your siblings, even if it was by just
opening the windows.
It is important that you let your mom know how you feel. The way she treated your concern was not correct. No matter her response you need to know that you made the right choices, and you should be confident in that.