Most studies say so! Our verbal language is around 10% from what we actually communicate! Most of the job is done by nonverbal language, or body language! So there os no big stretch to belive that it is true.
The air pollution makes the caribou unhealthy, and this makes them more vulnerable to predators and diseases.
Specifically, the food the caribou digest (for example lichens) absorb the pollution dispoportionally, which means that the caribou ingest many unhealthy particles.