Which indoor-air measurements are useful, and can I trust my monitor?

Choose the measurement for the question you are trying to answer. Our recommendation is to use a monitor to find patterns, then check important decisions with the right professional evidence. A green display does not certify that all the air in the house is safe.

A humidity reading can help you review added moisture. A particle reading can help compare a smoke or cooking pattern. A carbon dioxide reading can help a qualified ventilation provider investigate an occupied-room pattern. A broad volatile organic compound (VOC) display, about chemicals that can enter the air as gases, needs its own sensor explanation. Do not expect one of these readings to answer the others.

EPA explains that low-cost monitors detect only the pollutants or conditions their sensors are designed for. Their accuracy can vary with placement, humidity, temperature, other contaminants, and time in use. They also do not replace certified smoke or carbon monoxide emergency alarms. EPA's monitor guidance.

Before trusting a number, identify the exact device and sensor. Ask the maker what it measures directly, what it estimates, its units, accuracy range, care needs, and useful lifespan. Request independent testing relevant to indoor conditions if the purchase or a major equipment decision depends on it. A price or a brand name alone should not settle that question.

Placement needs a purpose. Follow the manual and use a representative occupied location rather than putting the monitor in the purifier's outlet or directly beside a source. Record the location when comparing results. Otherwise, a change in position can look like a change in the home. EPA advises avoiding immediate sources and drafts for general indoor readings.

Make a short log with time, room, activity, windows, HVAC operation, and cleaner setting. Compare similar periods and avoid changing several things together. That gives a professional useful evidence about what happens, rather than only a screenshot of the worst reading.

Ask what action a proposed measurement would change. For recurring dampness, building-moisture assessment may be more useful than a general air score. For an unexplained gas concern, an indoor-air professional can decide whether a targeted test is appropriate. For a filter decision, HVAC fit and airflow measurements still matter.

If health symptoms are part of the concern, bring the timing and readings to a clinician without treating them as a diagnosis. Your next step is to name the question, identify the sensor, and collect a consistent record. Confirm the equipment assessment MGI can provide and use a qualified indoor-air specialist for questions outside that scope.