Although I may contribute to marital discord in your household, I will answer honestly. Secondhand smoke is bad for cats. It’s bad for dogs, too.
Cats and dogs have exquisitely sensitive respiratory systems. Their lungs, bronchi (tubes that carry air into the lungs), windpipes, and sinuses all may suffer adverse effects from secondhand smoke.
Secondhand smoke can contribute to, cause, or exacerbate bronchitis, sinus infections, tracheobronchitis (also known as kennel cough), pneumonia, heart failure and lung cancer in pets. Secondhand smoke is especially notorious for exacerbating feline asthma.
I recommend that smokers with pets go outside to enjoy their cigarettes.