How to load Rtl/Ltr css conditionally in a Components styleUrls attribute

Question

What is the correct way to load css files conditionally into a Component in angular 4+ ?

@Component({...
    styleUrls:['./rtl.css','./ltr.css']...
})

In my case I need to load Rtl/Ltr css conditionally depending on a param provided by a service (here called _translateService).

this._translateService.onLangChange.subscribe((event: LangChangeEvent) => {this.lang = event});