Smell of smoke because of Easter fires

The smell of smoke that is present in large parts of the Netherlands, also in Amsterdam, appears to be caused by Easter fires.

Because of fog and lack of wind, the smell doesn't get blown away.

In many parts of Europe, huge bonfires are lighted on hilltops and in churchyards on Easter Eve. They are sometimes called Judas fires, because effigies of Judas Iscariot are frequently burned in them. The Easter Eve bonfires predate Christianity and were originally intended to celebrate the arrival of spring.

The fires are a tradition in large parts of Europe, from Denmark to Austria. In the East of the Netherlands an estimated 800 fires are lit, but not in or near Amsterdam as far as we know.