My German Shepherd has been having seizures, my breeder feels this is environmental. Do you know of any chemicals or substances that would cause this?

My 5 year old GSD had a seizure a month ago and was fine but had 3 today. I called our breeder who feels this in environmental since he has never had one before. We are remodeling our bedroom there is drywall dust, old paint. It has been quite a long process since our house is so old. The men working here today were doing some demo and kicked up a lot of old dust from our walls. Could this be the problem? They only lasted about a minute each one and he snapped out of it and was fine. They happened about 6 hours apart. Do you know of any known chemicals or substances that cause this?