The good news is that, unless an animal is confined in a pillowcase (as above) or in a room with extreme amounts of smoke, inhaling secondhand marijuana smoke is not likely to lead to intoxication. If this were a concern, it would be hard to walk the streets of San Francisco without catching a secondhand buzz.
If you have a message with multiple segments (a message over 160 characters will be broken up into 160-character segments), Twilio will queue the messages and release them at the rate of one message segment per second.
Conventionally, a byte of information can hold 1 character, so the simple answer is approximately 1000 million characters (which equates to roughly 200 million words). However, there are operating system overheads in managing disk space. Modern word processors often use 2 bytes per character to handle accented characters.