Evidence of organized "Twitter bombing" of Chicago city council while it was considering adding e-cigs to clean indoor air law

Jennie Harris and colleagues at Washington University St. Louis recently published a paper, "Tweeting for and Against Public Health Policy: Response to the Chicago Department of Public Health's Electronic Cigarette Twitter Campaign," that did a quantitative analysis of the "Twitter Bomb" campaign directed against the the Chicago City Council when it was considering adding e-cigarettes to the city's clean indoor air law.
 
They found an organized campaign -- based outside Chicago (and outside Illinois) -- to generate oppostion to the proposed ordinance.  Here is the summary of theor results from the abstract:

Of the 683 tweets mentioning CDPH during the week, 609 (89.2%) were anti-policy. More than half of anti-policy tweets were about use of electronic cigarettes for cessation as a healthier alternative to combustible cigarettes (358/609, 58.8%). Just over one-third of anti-policy tweets asserted that the health department was lying or disseminating propaganda (224/609, 36.8%). Approximately 14% (96/683, 14.1%) of the tweets used an account or included elements consistent with “astroturfing”—a strategy employed to promote a false sense of consensus around an idea. Few Twitter users were from the Chicago area; Twitter users from Chicago were significantly more likely than expected to tweet in support of the policy. [my emphasis]

The body of the paper also noted that

The majority of tweets appeared to be from legitimate Twitter users who oppose the regulation of e-cigarettes, and at least one advocacy group (CASAA) aiming to organize policy opposition messaging. However, our results suggested that 96 of the 683 tweets (14.1%) sent by 73 of the 307 Twitter users (23.8%) were using an account or tweet strategy consistent with astroturfing. The structure of the retweeting network was also consistent with findings from a study of astroturfing where a small number of accounts were responsible for a large proportion of retweets contributing to trending topics. [my emphasis]

 
The paper, published in the Journal of Medical Internet Research, is available here.
 
The Council passed the law by 45-4.