Why is this website free?

The founders of this website believe in open public access to information that is vital to people's well-being and creativity.
This website will always remain free to the public. It provides a service in the interest of improving the health of persons who may currently be exposed to tobacco smoke, by helping to bring about the understanding, and, eventually, the significant reduction or elimination of their exposure.
In the spirit of open exchange, this website was also constructed using Free Software, including Debian GNU/Linux, Drupal, R,
Apache, PHP, and MYSQL. The recent scientific research on secondhand tobacco smoke exposure, which underlies the simulation used on this website, was supported by the US government, the state of California, and private foundations. Please read about the current research on tobacco smoke exposure.