Indoor air quality problems in homes in Novato, San Rafael, San Anselmo, Larkspur and Sausalito usually come from one of four places: fine particles from outside (smoke, pollen), dust and dander from inside, moisture from damp crawlspaces and foggy weather, or a tight house that does not bring in enough fresh air. Equipment works when it is matched to the actual cause, so an assessment comes before any recommendation.
What we look at in an assessment
- Particles. We measure fine particle levels indoors, with the system off and running.
- Humidity, room by room and at the crawlspace if there is one.
- Odors and VOCs - smells from new furniture, paint, cleaning products, a garage or a damp area.
- The HVAC system itself: filter type and fit, the return duct, the indoor coil, the drain pan and any leaks that pull in attic or crawlspace air.
- How you live: pets, allergies or asthma in the family, cooking, how often windows open.
You get a plain summary of what we found and what each fix would do.
Matching the fix to the problem
| Concern | What helps most |
|---|---|
| Allergy symptoms at home, asthma triggers | Better filtration, sealed returns, duct cleaning if the ducts are dirty |
| Wildfire smoke | High-efficiency filtration, recirculation, a tight house, portable air cleaners for bedrooms |
| Pet odors and dander | Filtration plus regular filter changes; ventilation for odors |
| Humidity problems | Fix the moisture source; dehumidification where it stays damp |
| Stale air, stuffy rooms | Controlled fresh air through a ventilator |
| VOC concerns | Source control first, then ventilation; carbon filtration for some cases |
| Mold prevention | Dry crawlspaces, working drains, UV light on the indoor coil |
Filtration
The filter in your furnace or air handler is the main air cleaner in the house. Thin one-inch filters with high ratings can restrict airflow on systems with small returns, which makes the blower work harder and can freeze an AC coil. A media filter cabinet holds a deeper filter that catches fine particles with less restriction. We size the filter to the system, not the other way round, and install air purifiers or electronic air cleaners where they fit.
Smoke days
Wildfire smoke reaches Marin in some fall seasons, and fine smoke particles pass through basic filters. A system with a MERV 13 or better filter, run on recirculate with the fan on, cleans the air across the house; a portable HEPA air cleaner in the bedroom adds a clean room for sleeping. Prepare before the season: have spare filters on hand and know which setting closes the outside air. Our guide on wildfire smoke and indoor air goes through it step by step.
Damp air and mold
Many Marin homes struggle with too much moisture rather than too little. Fog near the water in Sausalito and Larkspur, cool damp winters and older homes over crawlspaces all push indoor humidity up. When it stays high, mold grows on cold walls, in closets and inside a neglected drain pan. The fix starts with the source - a wet crawlspace, a leaking duct joint, a bathroom fan that vents into the attic - and then humidity control where needed. A UV light on the indoor coil keeps that one damp spot clean. During long heating stretches some homes run dry instead, and we can check whether added humidity makes sense.
Fresh air for tight homes
Homes that have been sealed and insulated can trap cooking odors, moisture and stale air. An energy or heat recovery ventilator brings in filtered outdoor air and sends stale air out, while recovering much of the heat. It is the right answer for stuffiness that filtration cannot fix.
Keeping it working
Air quality equipment only works when it is maintained: filters on schedule, UV lamps replaced when they wear out, dehumidifier drains clear. We set up an ongoing maintenance plan with the visit. For the ducts themselves, see duct cleaning and duct repair. Town pages: indoor air quality in San Rafael and in Sausalito.