Drug use frequency among street-recruited heroin and cocaine users in Harlem and the Bronx before and after September 11, 2001.

We determined if illicit drug use frequency changes after a disaster by comparing drug use frequency in two street-recruited samples of heroin and cocaine users, ages 15-40 years. The users were interviewed between July 11 and November 11 and divided into before- and after-September 11th groups for analysis. The before and after groups were similar in the mean number of days of drug use per month (sniff cocaine 6.