Indoor air quality is about what you breathe at home: dust and allergens, mold spores and musty air, odors and chemical vapors, and whether enough fresh air comes in to dilute them. In Tiburon, Belvedere and Mill Valley the common complaints are dust in large, closed-up houses, damp and musty rooms on shaded lots, and smoke on the days when wildfire smoke drifts over Marin. Each has a different fix, which is why we start with an assessment rather than a product.
The assessment
- Your symptoms. What bothers you, in which rooms, and at what times of year.
- The home. Moisture, ventilation, pets, recent work, and how tightly the house is sealed.
- The system. Filter slot and fit, return-duct leaks, coil and blower condition, and whether the system can handle a better filter.
- Optional testing. Particle counts, humidity and other measurements when the cause is not clear.
- Recommendation. One or more solutions with upfront prices, starting with the simplest one that addresses the cause.
Solutions and what they address
| Problem | Likely sources | Solutions that work |
|---|---|---|
| Dust and allergens | Leaky returns, poor filters, pets, pollen | Sealing returns, a media filter cabinet, higher-efficiency filtration |
| Musty smell, mold | Humidity, damp crawlspace, drain problems | Dehumidification, fixing drains, cleaning where growth is present |
| Smoke and fine particles | Wildfire smoke, cooking, fireplaces | High-efficiency filtration with the fan circulating; portable or whole-house air cleaners |
| Odors and VOCs | New finishes, cleaning products, a closed-up house | Ventilation, plus carbon filtration for specific sources |
| Stuffy, stale air | Tight construction, windows kept shut | Balanced ventilation such as an ERV or HRV |
Filtration. The filter is the core of most solutions. A thin filter that fits poorly lets air slip around it. A four- or five-inch media cabinet holds a filter with far more surface, catching fine particles without choking the airflow.
Air purifiers. Whole-house electronic air cleaners and UV lamps at the coil are options in some homes. UV lamps help keep the coil and drain pan clean; they do not replace filtration. Portable purifiers sized for the room work well where there are no ducts.
Humidity control. In the coolest, dampest homes, a whole-house or crawlspace dehumidifier does more against mold than any filter.
Ventilation. An energy recovery ventilator (ERV) or heat recovery ventilator (HRV) swaps stale indoor air for fresh outdoor air while keeping much of the heat. In tight, remodeled homes it is often the missing piece.
Homes without ducts
Mini-splits and radiant floors have no central filter to upgrade. In those homes the filters in the indoor heads need regular rinsing, and portable purifiers or a dedicated ventilator fill the gap. If you are planning a mini-split installation or a heat pump, air quality is easier to build in from the start.
Local notes
Mill Valley homes under the redwoods and on steep, shaded lots stay cool and damp much of the year, and humidity, mold and crawlspace air are the usual root causes there; see our Mill Valley page. On the Tiburon peninsula and in Belvedere, large homes often have long return runs where leaks pull in attic or crawlspace dust. The local pages cover indoor air quality in Tiburon, Belvedere and Mill Valley. Ducts with visible buildup are covered under duct cleaning, and filters are checked on every HVAC maintenance visit.