My new apartment reeked like cat urine and moth balls. I had to have the carpet padding cleaned, the carpet cleaned 2x and I spray daily a cat urine odor remover on my floors and walls. If only people would spay/neuter. Mold will also cause smells, we found chunks of mold and rotten wood throughout our apartment. Replace your air filters, get air purifiers in every room or at least your bedroom and living room, I use a carbon and hepa filter. I have a bissel pet hair vaccume that works wonders, if you have a good income than I would suggest a Rainbow vaccume, my parents bought one because of my asthma when I was a girl. I also clean with tea tree oil and other aromatherapy oils. I put air fresheners in my air vents and have natural air fresheners throught out the house, I’m also currently buying a herb garden for my balcony so I have some flow of natural earthy smells. Good luck ,I hope any of this helps.