Indoor Air Quality at Home: Mold, Moisture, Sensors & Radon

Indoor air quality is not one score. It can involve particles, gases, moisture, ventilation, temperature, and pollutants from everyday activities and building materials. EPA’s examples include carbon monoxide, radon, mold, particulate matter, and volatile organic compounds.

The useful question is not simply “Is my air good?” It is “Which concern am I checking, and am I using the right measurement?” A radon test cannot identify mold, a humidity reading cannot identify a chemical, and a particle sensor cannot identify a gas.

They can affect some people, but the response is not the same for everyone. CDC says damp and moldy environments may cause health effects, or none at all. Reported effects can include a stuffy nose, sore throat, coughing or wheezing, burning eyes, or a skin rash. Reactions may be more serious for some people with asthma, mold allergies, immune suppression, or chronic lung disease.

A webpage cannot connect a symptom to a home. For symptoms or an individual health plan, talk with a qualified healthcare professional and use the CDC mold guidance as a calm starting point.

Routine home mold sampling usually is not the first or most useful step. CDC does not recommend routine mold testing, notes that there are no health-based standards for mold in indoor air, and says short-term samples cannot be interpreted as a home’s safe or unsafe level.

If mold is visible or can be smelled, CDC’s practical direction is to remove it and correct the moisture source. A qualified mold or building professional may be appropriate when the source is hidden, the area is extensive, sewage is involved, or occupants have health concerns. American Radon Systems does not inspect, sample, diagnose, or remediate mold.

CDC recommends keeping indoor humidity no higher than 50 percent if possible. A practical target for many homes is roughly 30 to 50 percent, adjusted for season and comfort. A basic hygrometer can show trends, but the number is only one clue.

Persistent condensation, wet materials, plumbing leaks, roof or foundation water, and poorly vented bathrooms deserve attention even when a nearby humidity display looks normal. Fixing the source of moisture matters more than chasing a perfect reading.

Cooking, especially frying or broiling, along with candles, fireplaces, tobacco smoke, dust-producing projects, aerosol products, vacuuming without effective filtration, and particles entering through open doors or windows can all change an indoor particle reading. PM_2.5 means fine particles with diameters of 2.5 micrometers or smaller.

A rise on a particle monitor can help reveal a pattern, but it may not identify the source. Note what was happening, where the device was placed, and whether the reading repeats. Reduce the source when practical before treating filtration as the whole solution.

No. Carbon monoxide is a poisonous combustion gas, and a dedicated carbon-monoxide alarm is a life-safety device. A multipurpose monitor may show several environmental readings without being designed or listed to provide a required CO alarm.

Keep dedicated CO alarms installed, maintained, and replaced according to their instructions and local requirements. If an alarm sounds, follow its emergency directions; do not wait for a general monitor or webpage to confirm the warning.

• CO: Carbon monoxide is a poisonous combustion gas. Maintain dedicated carbon-monoxide alarms as directed; do not assume a general air monitor replaces a listed life-safety alarm.
• CO₂: Carbon dioxide trends can provide clues about occupancy and ventilation. They are not a complete score for the health of the air.
• VOC: A consumer VOC sensor usually reports a broad signal or trend. It normally cannot identify a specific chemical or tell you its source.
• PM_2.5: A particle sensor can show changes from cooking, candles, dusty projects, and other fine-particle sources. Placement and device quality affect the reading.
• Humidity: Relative humidity helps reveal moisture patterns, but it does not confirm or rule out hidden mold or a leak.

Read the device instructions, look for repeatable patterns, and avoid treating one dashboard color as a diagnosis.

No. Radon requires a radon sensor or a separate radon test. Many monitors measure only temperature, humidity, CO₂, VOC trends, or particles. A device’s “air quality” score does not include radon unless its specifications explicitly say that it measures radon.

Before relying on a number, check the exact sensor list, units, sampling schedule, and manufacturer instructions. A consumer monitor can be useful for trends, but formal, medical, or real-estate decisions may require a different approved method or qualified professional.

As of this guide’s July 19, 2026 review, the manufacturer’s View Plus page lists seven sensors: radon, PM_2.5, carbon dioxide, VOCs, humidity, temperature, and air pressure. “PM” means particulate matter; it is not a measurement category called “plastic.” Product features can change, so confirm the current specifications before buying or relying on any monitor.

This is one useful example of why sensor lists matter, not a product recommendation. American Radon Systems is not affiliated with Airthings, does not sell air-quality monitors, and cannot validate a consumer device for medical, legal, or real-estate use.

A correctly selected and maintained HVAC filter or portable air cleaner can reduce airborne particles. Performance depends on the filter, airflow, room size, equipment, placement, maintenance, and how consistently the device is used.

Particle filtration does not repair a leak, remove mold growing on materials, or identify what caused a reading. EPA treats filtration as a supplement to reducing pollutant sources and using appropriate ventilation, not as a universal fix for indoor-air concerns.

Source control means reducing or removing the thing releasing a pollutant. Examples include fixing a water leak, exhausting moisture from a bathroom, avoiding indoor smoking, and venting combustion appliances as required. Preventing a pollutant from accumulating is often more effective than trying to capture it later.

Ventilation can dilute some indoor pollutants when clean replacement air is appropriate for the conditions and the home. Filtration can then provide another layer for particles. The right combination depends on the source, the pollutant, the building, and equipment instructions.

1. Maintain smoke and carbon-monoxide alarms according to their instructions and local requirements.
2. If radon is the concern, use a radon test or a monitor specifically designed to measure radon and follow its instructions.
3. Repair water entry and plumbing leaks, use bathroom and kitchen exhaust appropriately, and watch persistent humidity or condensation.
4. Reduce obvious indoor sources and use appropriate ventilation before expecting a filter or monitor to solve the problem.
5. Read each device’s sensor list and instructions. One monitor rarely answers every indoor-air question.
6. Take symptoms and urgent alarm warnings to the appropriate healthcare, public-health, fire, utility, or emergency professional, not a radon contractor.

This approach is less dramatic than chasing a universal “healthy air” score, but it is more useful: name the concern, measure it correctly, and take the matching action.