Let me tell you from the beginning it is not an easy task. Odors are VOCs, sulfur-containing compounds, and nitrogen-containing compounds. In most cases, odors come from rotten food inside the garbage bin or off-gassing materials that are new and of a low-quality like furniture, paint, and flooring.
Sulfur-containing compounds like hydrogen sulfide (rotten eggs smell), dimethyl sulfide (rotten cabbage smell), etc are produced during the anaerobic breakdown of food waste. They have a low odor threshold, which means that we can smell them even in only very small amounts.
Nitrogen-containing compounds like putrescine (rotting meat smell), trimethylamine (fishy smell), etc have a low odor threshold. Unlike ammonia (pungent smell) which is produced in large quantities, it has a higher odor threshold, so doesn’t contribute to indoor smell as much.
Another source of unpleasant odor indoors is the combustion of cigarettes/wood as the chemicals released from the burning biomass can infuse inside the walls and textiles. They call it thirdhand smoke as the residual contamination from smoke lingers indoors, and the cancer-causing substances such as formaldehyde can harm us.
What NOT to do!
Don’t mask the odors with perfumes and other air “fresheners” they are the worst for the indoor air quality. Aromatic candles and incenses are not a solution either. They emit lots of particles and VOCs. Stay away from all of them.
What to do!
Improve Airflow and Ventilation
The first thing you have to do whether you have a smelly house or not is to ventilate and bring fresh & clean air indoors. Cross ventilation for those without an HVAC system is the best and most efficient way to get rid of odors without losing too much heating or cooling for a brief period of time. CO2 and VOC-based monitors can help us understand if the house is well-ventilated.
Purify the Air
Air purifiers equipped with good filters can absorb some amount of odors but VOCs and other gas chemicals are harder to capture for a long period of time. Particulate pollution is a piece of cake for air purifiers but not gases.
Baking Soda & Activated Carbon
Baking Soda and activated carbon are other methods we can employ to absorb unpleasant odors. Baking soda is a natural deodorizer but it won’t detoxify your entire house from smells unless you order a tone of it. Activate carbon pellets have thousands of tiny holes where smells get trapped, this is what air purifier use. Unfortunately, they tend to saturate fast. Some people use coffee to mask bad smells which is safe but expensive and not resourceful.
Now, if you want a pleasant smell indoors just boil some distilled water with a cinnamon stick, some cloves, and some orange/lemon peels.
Clean with Simple Cleaners
It’s important to maintain our houses clean. You don’t have to buy fancy and expensive cleaning products with lots of chemicals. Dilute some soap to water and you have more than enough to clean everything. Some people use water with vinegar as the acetic acid in vinegar neutralizes alkaline odors such as fish. I don’t recommend it for everything though.
Find the Source
Last but not least, it is important to find the source of the odor and remove it. If you have someone smoking all day indoors or a garbage bin full of decomposed organic material there is nothing else you can do apart from taking them out of the house. Quite radical in the case a person smokes indoors, but if they don’t respect your heath then they don’t deserve to be close to you.