How chronic irritation leads to inflammation and diseases?

Throughout history, humans had to deal with inflammations. The main reasons for inflammatory diseases were and still are, injuries, bacterial and viral infections. Besides injuries, the reasons for inflammatory diseases were from food, water, and environmental contaminations due to poor personal hygiene and living conditions.
But that was then. Today we have food preservatives, refrigeration, and sanitation to keep contaminations out of food, drinking water, and from our living and working areas. We also have medical treatments for acute inflammation, like acute bronchitis, sinusitis, sore throat from cold and flu, and more. However, medical treatments don’t help heal chronic inflammatory diseases.