It would be better be written "Тихо. Я отдыхаю." to show these are independent clauses. There would be some ambiguity anyway, but I don't know how to translate your phrase without it. You could add a detail for that: "сейчас", "дома", "на работе": "На работе тихо. Я отдыхаю.", or connect the clauses like "Сейчас тихо, поэтому я отдыхаю".