Will smoking around my apple products void their warranty?
Apple warranty doesn't cover damage caused by (d) to damage caused by accident, abuse, misuse, fire, earthquake or other external cause so it's really a matter of how much nicotine, tar and smoke gets ingested into the product.

I have seen iMacs brought in for repair that were stained the color of a cigar and there were inches of dust and residue coating the blowers, vents and the internal temperatures were significantly above normal due to exposure to cigarette smoke. I've never seen an iOS device so coated with nicotine that it would be a problem since they don't have blowers / fans and need airflow to function properly, but I have faith that someone is capable of getting enough coating on anything to cover up any size gap large or small with enough effort. 

It's really up to Apple whether they cover each repair based on how they train their service staff and common sense shows that most devices won't be affected enough by smoking to matter. It's not so much as voiding a warranty as the warranty is designed to cover defects in manufacturing and not problems caused by operating environments that are extreme or prolonged.

If your product were placed in a sealed plastic bag and you took it to a smoke free room and had a child sniff it - you probably wouldn't be denied service for something that wouldn't make someone recoil from the amount of nicotine and tar that permeated the air left in the bag after a few hours of being removed from the environment where it normally is stored and used.