Green’s Dictionary of Slang

1. a cigarette laced with heroin.

1972		Smith & Gay Heroin in Perspective 201: Duster. Heroin cigarette (prevalent now in Vietnam).
1981		D.E. Miller Bk of Jargon 341: duster: A cigarette composed of heroin mixed with tobacco.
2000		T. Fontana ‘A Cock and Balls Story’ Oz ser. 4 ep. 1 [TV script] ‘This is for you.’ ‘Marijuana?’ ‘Yeah, plus a little something [...] we call it a duster’.

2. (drugs) a user of phencyclidine.

1979

H. Feldman et al. Angel Dust 126: Most of the other ‘dusters’ were introduced in the ways they bumped into all other drugs.