What sorts of things trigger sinuses and allergies to act up?

Virus, allergens. Viral infections are the most common cause for worsening nasal and sinus symptoms. Increased exposures to allergens or even irritating fumes and odors or smoke can be causes.
Allergens/pollutants. Allergens like house dust mite, pet dander, cockroach, pollen, mold spores. Nasal irritants like tobacco or fireplace smoke, smog, diesel exhaust, strong fragrances. Viral infections.