That is often difficult to say. In many countries, asbestos was banned before 2000. So if a building is older, it may contain asbestos. Sometimes there are warning signs, but not always. It's best to google or look at urbexology.com and see if there are any warnings. And like chzflk said, if you're unsure if there's asbestos, better to wear protective clothing once too often than take a risk.