maPollution is the application that gives you the forecast of air pollution for the next 4 days and in 3700 cities (and around) in the world (Europe, Asia, Africa, Australia, Americas) and in Europe, it informs you of the risks concerning the 5 most annoying pollens: grasses, birch, mugwort, ragweed and alder in the next 4 days. You can thus be protected from the risks of pollution and allergies and adapt your behavior. In Europe you can be alerted (in the morning via a free option ) by notifications in the event of a risk of pollution or a pollen episode even when the application is on standby and it's free. 
The APP has a widget companion , It doesn't ask you for your email... some options need opt-in to a service in Europe, and the opt-out is immediat. All you have to do, is to set your personnal threashold in the App and follow the screens. None of your personnal data is used by our plate-form. All we need stays in your iPhone, and all is free !