Reports by the Congressional Research Service from 2008 discuss emerging policy issues regarding carbon dioxide pipelines for carbon sequestration, network needs and cost uncertainties regarding pipelines for carbon dioxide control, and jurisdictional issues in regulating carbon dioxide sequestration pipelines.
Total numbers of speakers is high: over 40 million Farsi speakers (about 60% of Iran's population); over 14 million Dari Persian speakers in Afghanistan (50% of the population according to CIA World FactBook & Britannica); and about 2 million Dari Persian speakers in Pakistan.
The majority of the people of Tehran are Persian-speaking people, and roughly 99% of the population understand and speak Persian; but there are also large populations of other Iranian ethnicities in the city such as Azerbaijanis, Armenians, Lurs and Kurds who speak Persian as their second language.