What problems would perpetual fog cause to a country roughly the size and environment of Ireland?
The country has all modern infrastructure such as power plants, roads, factories, hospitals, etc.
For just over half the year the fog is very thick and only allows for around 200 m of visibility. The rest of the year the fog is mild, but the weather is often cold and rainy with odd days of sunshine.
The lengths of time the fog is bad is sporadic, sometimes lasting a few days others lasting a few months.
If any more information is required please let me know in the comments.