On 2016 Aug 24, DAVID ALLISON commented:

We write to correct a misstatement in the above referenced article. The article stated “On gestation d 4, rats were randomized into 2 groups: 18 entered the unfiltered chamber, and the remaining 12 entered the filtered chamber”. One of us (DBA) contacted the others (JZ and YW) to inquire how and why the 3:2 allocation was achieved in the randomization and upon dialogue it became clear that allocation was not via randomization. The sentence should be corrected as “On gestation d 4, rats were assigned into 2 groups: 18 entered the unfiltered chamber, and the remaining 12 entered the filtered chamber. The assignment was done by consideration of baseline body weight in such a way that the baseline weights were not significantly different between the two groups.”

Sincerely,

Jim Zhang, PhD<br> Professor of Global and Environmental Health

Yongjie Wei, PhD Associate Professor Chinese Academy of Environmental Sciences

David B. Allison, PhD Distinguished Professor University of Alabama at Birmingham

On 2016 Aug 24, DAVID ALLISON commented:

We write to correct a misstatement in the above referenced article. The article stated “On gestation d 4, rats were randomized into 2 groups: 18 entered the unfiltered chamber, and the remaining 12 entered the filtered chamber”. One of us (DBA) contacted the others (JZ and YW) to inquire how and why the 3:2 allocation was achieved in the randomization and upon dialogue it became clear that allocation was not via randomization. The sentence should be corrected as “On gestation d 4, rats were assigned into 2 groups: 18 entered the unfiltered chamber, and the remaining 12 entered the filtered chamber. The assignment was done by consideration of baseline body weight in such a way that the baseline weights were not significantly different between the two groups.”

Sincerely,

Jim Zhang, PhD<br> Professor of Global and Environmental Health

Yongjie Wei, PhD Associate Professor Chinese Academy of Environmental Sciences

David B. Allison, PhD Distinguished Professor University of Alabama at Birmingham