To add to the other answer which mentions air pollution, here's a possible cause of the pollution:
You mentioned that your country is on the coast and that it spans into the continent. As shown by the following diagram, volcanoes occur in mostly coastal regions:
This means your country could have a string of volcanoes along its coast. If the general wind patterns push air into the continent from the direction of the coast, then a prolonged eruption would cause a constant influx of volcanic ash into the air of your country. This would reduce visibility.
The extent to which it does this is up to you - look at the Toba eruption, which may have caused a global cooling period of up to 1000 years. Alternatively, the volcanoes could simply be slow burning. Rather than a huge, dramatic explosion, they could constantly release ash into the air, which is dragged inland by the wind. This is all up to you of course and depends on what you want to do with the story. Hope this helps.