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.
So (ignoring unicode for the moment) you can send a message of 35 * 153 = 5355 characters via the Clickatell API. If you are sending unicode characters (which the OP is not) the character count for a single message is 70, reduced by 7 characters for each segment in concatenated message or 63 * 35 = 2205 unicode characters.