Here's what Monica Chen of New Roots (formerly Factory Farm Awareness)  says at the beginning of letter going out:

Did you know that factory farms are exempt from the Clean Air Act? This means they’re allowed to emit hydrogen sulfide and ammonia at levels higher than the EPA permits for the oil and gas industry.

This came in when I was writing a letter to the editors of the San Francisco Chronicle:

There's a connection between Peter Hartlaub's article on the fire station decoration contest and Patti Breitman's letter to the editor of  December 24th.  Both mention the manger scene, which Peter Hartlaub reports was created by one fire station between 1948 and 1950 when it "borrowed live animals on route to a local slaughterhouse and used them in a manger scene."  Patti Breitman pleads for showing concern for the animals at peace in the manger scene by abstaining from eating them, an act of kindness in an era when cats and dogs are part of our family but we treat farm animals like insensate beings and accept their suffering  on route to our stomachs.  I want to know more about the incident with the animals temporarily rescued from slaughter.  How did they adjust to the manger scene?  What was their ultimate fate?  I can't find anything online.  Could Peter Hartlaub dig into the archives and do a follow-up?