Hello Stephanie,
There are two methods I always used and they have worked:
1.
Ozone machine - I used the same ones that were used to get the smoke smell after a fire in a unit. Now some use a company to come in and do it, but the charge is going to be high. so go with companies that sell the machines and buy one business to business. Get your maintenance personnel to understand where to place it and how to use it. In the long run, it will pay for itself in that you do not have to hire a company to come in and do the work. Now all ozone machines are not egual and what you want to know here is how many cubic feet of air is circulated through the filter in a minute. Know the size of your rooms and close doors and concentrate first in the area with the heaviest smell. Oh, one other thing is you want to watch out for knockoff systems and how much power a machine draws, so you can calculate in your costs.
2. Plants that clean the air - The best plants for improving indoor air quality include the philodendron, spider plant, English ivy, peace lily, Chinese evergreen, bamboo palm and golden pothos. Some of the more effective plants to clear out formaldehyde include the Boston fern, dwarf date palm, bamboo palm, English ivy, weeping fig and lady palm.
These plants are nice gifts to the new resident.