With a rise in child asthma and seasonal allergies , can this increase be due to something being released in our environment?

Due to lack of germs: Rather than something added, most experts feel increase in allergic conditions is due to lack of exposure to bacteria in infancy due to our hygienic enviroment, the "hygiene hypothesis." there is a balance between bacteria in environment and our immune system so removing bacteria allows part of the immune system leading to allergies to over-react, producing more allergic antibodies (ige), etc.

Asthma rising: In part both patients and physicians are more likely to understand this problem and obtain a diagnosis. Climate changes in some areas can change pollination seasons, industrial pollution is always a factor as well as tobacco second hand smoke but there are improvements there recently. Inner city cockraoch infestation with allergy is still a problem. Some variables are not totally understood.

Yes: Most definitely. As well as food allergies and household chemicals.