My husband poured a box of "New Fresh Step Natural" litter into our litter box tonight. I was two rooms over and began to choke. The dust filled our entire house. We had to open our windows (in the middle of the summer in Phoenix, AZ) and set up fans to try to move the dust out. Hours later, we are all still finding it difficult to breathe in the house. I have never experienced anything like this in the 12 years I have had cats!