yeah thats probly right, inner parts of forest would be cleaner air wise dust gets trapped on leaves and stuff but sunlight is probly a bigger issue, less of it gets thru all the dust and thats bad for plants and animals alike, especially ones that need lots of it like big herbivores and their predators, theyd struggle to survive on limited sunlight and maybe even worse air quality than outer parts of forest, generalist animals like birds and small mammals would do ok tho, they can eat lots of diff things and dont need as much sunlight