Service
Indoor Air Quality Testing in San Diego County
Radon in context: humidity, particulates, ventilation, and combustion safety assessed together.
Radon is one component of indoor air quality, and it is the one with the clearest link to a serious health outcome. But the conditions that let radon in, weak ventilation, pressure imbalance, unsealed soil contact, also let in moisture, particulates, and combustion byproducts.
Testing them together produces better decisions. A home with high radon and high humidity from an open crawl space has one root cause and one fix. Treating them as separate projects costs more and solves less.
The assessment covers radon, relative humidity, temperature stratification, particulate levels, carbon dioxide as a ventilation proxy, and a combustion safety check where atmospherically vented appliances are present.
Why this work matters
- People in California spend the large majority of their time indoors, so indoor concentrations dominate total exposure.
- Energy-efficiency upgrades tighten the envelope and reduce the accidental ventilation that once diluted indoor contaminants.
- Humidity above roughly 60 percent supports mold and dust mite growth, both common asthma triggers.
- Combustion appliances in depressurized spaces can backdraft, which is an acute rather than chronic hazard.
Signs this service applies to your building
- Persistent stuffiness, headaches, or odors that clear when windows open.
- Condensation on windows or musty smells at floor level.
- Allergy or asthma symptoms that worsen at home.
- A recently weatherized home with no mechanical ventilation added.
- Visible dust accumulation or discolored HVAC filters shortly after changing.
- Gas appliances in a closet or utility space shared with exhaust equipment.
How the process works
- 1
Occupant interview and walkthrough
Symptoms, timing, room-by-room complaints, renovation history, and appliance inventory are documented before instruments are deployed.
- 2
Multi-parameter monitoring
Radon, humidity, temperature, particulates, and carbon dioxide are logged simultaneously over at least 48 hours.
- 3
Ventilation assessment
Outdoor air delivery, exhaust fan performance, and whole-house ventilation, if any, are measured against the building's size and occupancy.
- 4
Pressure and combustion safety check
Worst-case depressurization testing verifies that exhaust equipment cannot backdraft a naturally vented appliance.
- 5
Source identification
Findings are traced to causes: soil contact, duct leakage, insufficient ventilation, or a specific material or activity.
- 6
Prioritized recommendations
Fixes are ranked by health impact and cost, starting with source control and moving to ventilation and filtration.
Equipment and materials involved
Continuous radon monitor
Hourly radon data alongside the other parameters for correlation.
Particulate counter
Measures fine particulate concentrations that affect respiratory comfort.
Carbon dioxide logger
Serves as a practical proxy for how much outdoor air the home actually receives.
Thermo-hygrometer data loggers
Track humidity and temperature across rooms and over time.
Combustion analyzer and draft gauge
Verifies that fuel-burning appliances vent properly under worst-case conditions.
What you get out of it
- One coherent picture instead of several disconnected tests.
- Root-cause fixes that address radon and moisture together where they share a source.
- Documented conditions to compare against after improvements.
- Safety verification for combustion appliances.
- A prioritized plan rather than an undifferentiated list of problems.
San Diego County considerations
Coastal marine layer keeps outdoor humidity elevated for much of the year in beach communities, which changes ventilation strategy compared with inland valleys.
Inland heat in Escondido, Santee, and El Cajon drives long periods of closed windows and air conditioning, concentrating whatever the home generates internally.
Wildfire smoke events have made filtration and envelope tightness a mainstream concern countywide, and tighter homes hold radon more effectively too.
The regional prevalence of slab foundations and raised crawl spaces means soil contact is often the shared source behind both radon and moisture complaints.
Frequently asked questions
Is radon testing part of an indoor air quality assessment?+
It should be, and here it is central rather than an add-on. Radon is the indoor air contaminant with the most firmly established serious health outcome, and it is invisible to every other test. An assessment that measures particulates and humidity but skips radon has left out the one parameter that could matter most for long-term health.
Will an air purifier fix radon?+
No. Portable air cleaners filter particles and, with activated carbon, some gases, but they do not meaningfully remove radon or its short-lived decay products from the volume of air in a home. Radon is addressed by keeping it out of the building through soil depressurization, not by cleaning the air after it arrives. A purifier is a reasonable tool for particulates and a poor one for radon.
What humidity level should I aim for?+
Generally between 30 and 50 percent relative humidity, with 60 percent as an upper limit before mold and dust mite growth become likely. In coastal San Diego, summer marine air makes the upper end harder to hold in homes with open crawl spaces. Sealing soil contact usually does more for indoor humidity than adding dehumidification capacity.
How does ventilation relate to radon?+
It cuts both ways. More outdoor air dilutes indoor radon, which lowers concentration. But exhaust-dominated ventilation, lots of bath and kitchen fans with no makeup air, depressurizes the house and actively pulls more soil gas in. Balanced ventilation helps; unbalanced exhaust ventilation can make radon worse while improving other parameters.
How long does an assessment take?+
The on-site walkthrough, ventilation measurement, and combustion safety check typically take two to four hours. The logging instruments then stay in place for at least 48 hours to capture day-night variation, so the full process spans two to three days from setup to report. Longer deployments produce better data when a complaint is intermittent.
Related reading
Related services
Available throughout the county
- Indoor Air Quality in San Diego
- Indoor Air Quality in La Jolla
- Indoor Air Quality in Del Mar
- Indoor Air Quality in Carlsbad
- Indoor Air Quality in Encinitas
- Indoor Air Quality in Poway
- Indoor Air Quality in Escondido
- Indoor Air Quality in Chula Vista
- Indoor Air Quality in El Cajon
- Indoor Air Quality in La Mesa
- Indoor Air Quality in Santee
- Indoor Air Quality in National City
- Indoor Air Quality in Coronado
- Indoor Air Quality in Imperial Beach
- Indoor Air Quality in Pacific Beach
- Indoor Air Quality in Mission Valley
- Indoor Air Quality in Clairemont
- Indoor Air Quality in Mira Mesa
- Indoor Air Quality in Rancho Bernardo
- Indoor Air Quality in Rancho Peñasquitos
- Indoor Air Quality in Carmel Valley
- Indoor Air Quality in University City
- Indoor Air Quality in Point Loma
- Indoor Air Quality in Hillcrest
- Indoor Air Quality in North Park
- Indoor Air Quality in South Park
- Indoor Air Quality in Ocean Beach
Not sure where to start?
Testing is the first step. Send a note describing your home, its foundation type, and any test results you already have.