Contaxt allergy only in Barcelona?

Hello everyone, I’d love to get your thoughts on the following situation:

I have a few allergies (Alternaria, European ash, and dust), and every time I visit Barcelona, I develop a strong rash on my legs that seems like some kind of contact allergy.

Before my visits, I took my usual medication (levocetirizine) for my Alternaria allergy, as I always do. The rash mainly affects the exposed areas of my legs, but there is also a milder reaction on some of the covered areas.

I don’t normally have any problems with sun exposure, and I don’t get the same reaction on my exposed shoulders or arms. I’ve also visited several other European cities during the (hot) summer and never experienced anything similar.

However, I’ve now been to Barcelona three times during the summer (just for normal city trips, but all around July or August), and every time I developed the same red rash on my legs. It isn’t itchy, but it feels slightly irritated when touched. I also hadn’t applied any creams or other products to my legs. I also visited different locations in Barcelona every time.

Has anyone experienced something similar in Barcelona or has any idea what could be causing this?