Find the right guide.

Set up your Terrestream

Set up with the mobile app, a computer, or use the sensor on its own.

Connect Terrestream to Alexa

Enable the Terrestream skill, choose your sensors and set up readings and routines. US English.

What is IAQ?

One number for particles: the worse of the PM₂.₅ and PM₁₀ sub-indices, on the same 0–500 scale as the U.S. EPA AQI. It does not include CO₂, VOCs or NOₓ.

Carbon dioxide indoors

Every exhale adds CO₂ to a room. Rising readings can help you spot when ventilation is falling behind occupancy; they do not diagnose symptoms or concentration problems.

PM2.5: the fine stuff

Particles smaller than 2.5 micrometers slip past your nose, lodge deep in the lungs, and cross into the bloodstream. They are the single most-studied air pollutant.

PM10: dust, pollen, and the coarse fraction

Larger particles that mostly get filtered in the upper airway, but they still matter for allergies, asthma, and visibility.

VOCs: the invisible smell

Volatile organic compounds are the carbon-based gases evaporating off everything: cooking, candles, paint, new furniture. Some are merely annoying. Some are not.

NOₓ: gas stoves, traffic, asthma

Nitrogen oxides come from combustion. Indoors, the main source is a gas stove. The health link with childhood asthma is robust.

Humidity: the 30 to 50 percent rule

Below 30%, your throat dries out and viruses last longer. Above 60%, mold and dust mites thrive.

Temperature: comfort, sleep, productivity

ASHRAE defines a comfort zone. The bedroom is its own special case: cooler is better.

Barometric pressure: weather, altitude, headaches

Pressure rarely changes how the air feels, but it changes how the body feels. It is also the most reliable indoor weather forecast you have.

Lux: light, circadian rhythm, and screen time

Light is information your body uses to set its clock. Most indoor environments give it the wrong information.

AQI vs IAQ: the same scale, two contexts

Both numbers use the same 0–500 color band, but the math is different and so is the answer to "is it bad?"

Pollen and ozone: the outdoor numbers that change your indoor advice

When outdoor ozone or pollen is high, "open a window" stops being good advice.

Terrestream measures CO₂ only - it does not measure CO. Use UL-listed CO alarms.

CO vs CO₂: we measure one, not the other

Carbon monoxide and carbon dioxide sound alike and the abbreviations look alike. They are completely different gases. Terrestream measures CO₂ only.

Ultrafine particles: what the sensor cannot see directly

Below 100 nanometers, particles get small enough to cross from lungs into bloodstream. The SEN66 sees PM₁ but stops there.

Wildfire smoke: what is in it, what to do

A complex aerosol dominated by PM₂.₅, with VOCs, NOx, and dozens of trace species. Indoors, the right response is to seal up and filter, not ventilate.

Mold: Terrestream is not a mold detector

Terrestream does not detect mold or count spores. It reports temperature, pressure, and relative humidity - conditions that are sometimes associated with mold. Mold can also grow in conditions and places the sensor never sees.

Dust mites: the bedroom ecosystem you cannot see

House dust mites need humidity to reproduce and warmth to thrive. The sensor reads both. Allergen is in the air whenever the bed gets disturbed.

Pets and indoor air: dander, litter, and sensitive animals

Dander is an allergen, not a reading the sensor can identify. Here is what the particle readings can and can't tell you, how to cut exposure at home, and why birds and other pets are more sensitive to indoor air than people.

Sulfur dioxide: the outdoor number for fuel and fire

SO₂ comes from burning sulfur-bearing fuels: coal, heavy oil, diesel ships, volcanic activity, and wildfires. The device does not measure it; the dashboard pulls it from Open-Meteo.

Gas-stove cooking: the fingerprint

A pan on a gas burner produces a remarkably consistent multi-pollutant signature: NOx, fine and ultrafine particles, VOCs, and humidity, rising and falling together. Each cooking method leaves its own version of it.

Candles and incense: small flame, big PM spike

A single candle can push a small room past 100 µg/m³ PM₂.₅ in under ten minutes. Incense is worse.

Cleaning products: the VOC spike you can smell

Pine, citrus, ammonia, bleach. Most cleaning products produce sharp VOC spikes; some combinations are acutely toxic.

New furniture and paint: the slow VOC bleed

Particleboard, foam, finishes, and many paints off-gas formaldehyde and other VOCs for weeks to months. A new sofa changes the room's baseline.

Bedroom overnight: the CO₂ climb you sleep through

Two adults in a closed bedroom can push CO₂ past 2,000 ppm by 4 AM. The math is unforgiving.

Attached garages: the highest-risk source in most homes

A running engine ten feet from your living space. Cold-start emissions are the worst. Door seals matter more than you think.

WHO vs EPA: two number systems, two philosophies

EPA NAAQS is regulatory. WHO 2021 is aspirational. Terrestream uses the EPA scale; this is how to compare your readings with both.

ASHRAE ventilation rates: the math behind "open a window"

ASHRAE 62.1 covers commercial; 62.2 covers homes. Both give you a number in CFM per person.

Health Canada residential guidelines

Canada publishes its own residential indoor air guidelines, one pollutant at a time. The NO₂ limits are much stricter than U.S. outdoor standards; for PM₂.₅ there is no number, only "as low as possible."

WELL, RESET, LEED: building-level certifications

For commercial buildings, three certifications dominate the indoor-air conversation, and codes such as California's Title 24 set design rules. Each weighs different things, and none of them is conferred by a sensor.

Children: higher exposure, more vulnerable lungs

Kids breathe faster and take in more air for their body weight than adults, spend more time indoors, and have lungs that are still developing.

Asthma triggers: the indoor list

Asthma is the most common chronic disease in children. Several common indoor triggers leave a trace the sensor can see; others don't.

Cardiovascular disease and PM₂.₅

PM₂.₅ kills more people through hearts than through lungs. The mechanism is systemic inflammation, oxidative stress, and direct arterial effects.

HEPA purifiers: the CADR math

A HEPA filter is the most effective single intervention for indoor particulates. Sizing it correctly is the part most people get wrong.

The Corsi-Rosenthal box-fan filter

A $50 box fan, four MERV-13 furnace filters, and twenty minutes of construction. Tests have measured clean air delivery rates of roughly 400 to 850 CFM.

HVAC MERV ratings: what your furnace filter actually does

MERV 8 catches dust. MERV 13 catches viruses. MERV 16 catches almost everything HEPA does. Most homes ship with MERV 6.

Range-hood venting: the single biggest cooking intervention

A hood vented outdoors, run on high over the back burners, can capture most cooktop emissions; many installed hoods capture far less. A recirculating hood returns the gases to the kitchen.

How the sensor sees: optical CO₂ vs MOX

CO₂ is read by pulsing infrared light the gas absorbs and listening for the pressure wave. VOCs are read by watching a hot ceramic surface change conductance. Different physics, different limits.

Cross-sensitivities: what confuses each sensor

Every sensor has things it sees that it shouldn't. Knowing the cross-sensitivities is how you read the right story in the numbers.

Why your reading differs from the nearest EPA monitor

Three reasons your number rarely matches the official outdoor AQI: hyperlocal variation, time resolution, and calibration class.

Co-movement patterns: the fingerprint catalog

A single metric tells you a number. Several metrics moving together tell you what happened.

Dew point: the number that says it's sticky

Relative humidity is relative to temperature. Dew point is absolute. If you want to know whether the air is "muggy," dew point is the number.

Apparent temperature: what your body feels

The thermometer reading is just the air. Heat index and wind chill account for humidity and wind: closer to what your body experiences.

UV index: sunburn risk in a single number

The UV index condenses solar ultraviolet intensity into a 0–11+ scale. Above 6, take precautions. Above 8, every minute counts.

Wind and infiltration: how the outdoors gets in

Outdoor wind drives air through small cracks and gaps in your building. Higher wind = more outdoor air entering, whether you want it or not.

Pollen species: the six that matter most

Alder, birch, grass, mugwort, olive, ragweed: European pollen forecasts track each separately, and the seasons are very different. Terrestream's pollen levels come from Google.

Precipitation: the great atmospheric scrubber

Rain and snow wash particles out of the air, but not all sizes equally: pollen, dust and the tiniest particles go quickly, while most fine-particle mass lingers.

Wood stoves and fireplaces

Solid-fuel combustion produces the largest, longest-lasting PM event most homes ever see indoors. Even a well-tended fire shifts the baseline for hours.

Vaping, smoking, and cannabis

Tobacco smoke, cannabis smoke, and vape aerosol all show on the sensor, and their health profiles differ significantly. Here is what each looks like indoors, how it travels, and what helps.

Bathrooms and showers

A hot shower is a daily humidity event with a side of cleaning-product VOCs. Recognizable, mostly harmless, occasionally a mold-risk signal.

Where to put the sensor

Counter-height, away from vents and windows, in the room you actually use. The placement choice changes what you can interpret.

Open vs. closed windows

The single most consequential daily decision the dashboard helps you make. Six outdoor signals, three indoor signals, one answer.

Central-dashboard monitoring for schools, offices, and industry

Many sensors across a building or campus, one workspace, and a queue of the rooms that need attention. A Facilities account adds campus and building views, team roles, room history, and email and text alerts during the coverage hours your team sets.

A renter's guide to indoor air

You can't replace the HVAC, but you can do most of what matters. Eight interventions that need no landlord permission.

Demand-controlled ventilation

Run the HVAC harder when people are in the room, less when they aren't. CO₂ sensors are how it knows.

Productivity and air quality

Decisions get worse, errors rise, and absences increase as air quality drops. The literature quantifies it; the dashboard surfaces it.

Sick building syndrome

A cluster of complaints with no single identifiable cause, and easy to confuse with building-related illness and multiple chemical sensitivity. The label has fallen out of fashion; the underlying problems haven't.

Classroom CO₂ and learning

Test scores correlate with ventilation rates. Attendance correlates with ventilation rates. The literature is unusually consistent.

EPA IAQ Tools for Schools

The U.S. EPA's structured framework for school IAQ management. Free, well-documented, widely adopted.

Schools and wildfire smoke

Close, mask, or shelter-in-place? AQI thresholds, building envelope, and student-population considerations.

What Terrestream can and cannot tell you

The dashboard interprets your air. It does not diagnose you, replace your doctor, or detect things the sensor cannot measure.

Dashboard vocabulary

How to read the dashboard and the apps: what band, baseline, spike, trend, anomaly, fingerprint, confidence and cross-reference mean.

Recovery curves: how long until the air clears

After a source stops, each pollutant decays with its own characteristic shape. The math behind "the room should clear in about 20 minutes," and why real rooms don't always follow it.

Time scales of air quality

Minutes to seasons. Knowing which time scale a parameter lives on is half of interpreting it correctly.

How parameters interact

Air-quality parameters do not change in isolation. Humidity pushes the VOC index. Ozone reacts with limonene to make formaldehyde. Knowing the interactions helps you avoid false alarms.

Cumulative vs acute exposure

A bad afternoon and a bad decade are different problems. Dose, peaks, and several mild elevations at once: what the literature says matters for what.

Benchmarking your home

Is your air normal? Population-level studies and the dashboard's own data let you compare to typical homes.

Risk vs hazard vs exposure

Three words public-health professionals use carefully. Loose usage in air-quality conversations causes most of the misinterpretation.

How anomaly detection works

When a reading is far outside what is usual for that room, Terrestream flags it and suggests what to check instead of guessing a cause. That is by design.

Climate zone effects

The same reading means different things in cold-dry, hot-humid, and temperate climates. Knowing your zone tells you which problems to watch for.

Building type priors

Apartments, townhomes, detached single-family, and commercial buildings each have characteristic air-quality patterns. Knowing yours helps you read the numbers.

Seasonal IAQ shifts

Winter, spring, summer, fall. The dominant indoor-air pressure changes with the calendar.

Moving into a new home

The first month is when off-gassing peaks, cleaning is heaviest, and the dashboard learns your normal. Expect noise; expect resolution.

Holiday and gathering patterns

Turkey day, parties, holiday candles, family visits. Combined source events look different from any single source.

Older adults and air quality

Cardiovascular sensitivity, frailty, medication interactions, and time indoors all shift with age, so indoor air becomes a bigger share of total exposure.

Canadian Air Quality Health Index

Canada uses a 0–10+ health-risk index instead of the US 0–500 AQI. Different math, different recommendations, same goal.

Multi-room comparison

Two sensors tell more than one twice. The difference between rooms is often where the real story is.

Circadian and ambient context

Time of day is a meaningful signal: many air-quality readings rise and fall with the sun and with the household's daily routine.

Returning home: vacation recovery

A sealed empty home behaves predictably while you are gone. The first 24 hours back tells you what changed.

Where do the numbers come from?

Every reading on the dashboard has a source: a sensor on the device, a computation from sensor inputs, or an outdoor API. Knowing which is which is the first step in interpreting any of them.

The PM size cascade

PM10, PM2.5, PM1.0, ultrafines. Same physics, different particle-size buckets. The size determines where particles lodge in the body and what produced them.

Four air quality indices, compared

EPA AQI, WHO 2021 guidelines, Canadian AQHI, European CAQI. Four different ways to summarize the same air.

Filtration approaches, compared

HEPA, MERV, Corsi-Rosenthal. Three filtration paths to the same goal. Cost, performance, deployability differ in different directions.

Ventilation approaches, compared

Open windows, range hood, HRV/ERV, demand-controlled ventilation. Different ways to bring fresh air in and stale air out.

Combustion sources, an overview

Anything that burns indoors produces a multi-pollutant signature: NOx, fine particulates, VOCs, ultrafines, and (sometimes) CO. The dashboard has a shared interpretation framework for all of them.

Allergen sources, an overview

Mold, dust mites, pet dander, pollen, mold spores. Most household allergen exposure is one of these five. The dashboard groups them as a family.

The feel of air

Sometimes a room feels wrong even when every number looks normal. Comfort depends on several readings at once, above all temperature and humidity together.

Weekend vs weekday patterns

Most households run on a 5-and-2 schedule. The air does too, and Terrestream learns each room's weekly CO₂ routine.

Aerosol Optical Depth

What satellites see when they look at our atmosphere. Aerosol Optical Depth quantifies how much sunlight gets scattered or absorbed by particles, and it lines up with ground-level PM in useful ways.

Mineral dust events

Saharan dust to the Caribbean and Texas, Asian dust to the Pacific Northwest. Distinct from wildfire smoke chemically, sometimes visually similar.

Visibility as air quality

How far you can see is a rough but useful gauge of how much fine particulate is in the air, as long as the air is dry.

Cloud cover and photochemistry

Cloudy days produce less outdoor ozone. Sunny days produce more. Ozone forecasts build that in, and Terrestream reads the ozone forecast for your home's location.

Solar radiation and air chemistry

Direct radiation, diffuse radiation, shortwave total. The numbers behind outdoor ozone, indoor lux, and the circadian signal all come from the same place.

Snow depth and winter IAQ

Fresh snow scrubs particulates from outdoor air. Persistent snow traps cold air at the surface, sometimes for days, with all that implies for inversions.

Tree pollens, regional

A short list of headline genera covers the broad strokes, but tree pollens vary by region. Oak in the South, cedar in Texas, maple in the Northeast, birch in the North.

Mold spore forecasts

Outdoor mold spore counts are tracked alongside pollen by allergy services. Different biology, often confused, sometimes the actual culprit when pollen seems low.

Radon: an alpha-particle hazard we cannot detect

Radon is the second-leading cause of lung cancer in the US after smoking. It cannot be detected by any optical, NDIR, or MOX sensor; only alpha-particle counters can see it.

What Terrestream does not measure

Terrestream measures a specific set of air-quality parameters. There are many hazards it does not measure at all - here is a non-exhaustive list of common ones, and the dedicated detector or test to use instead.

Lead paint and renovation dust: a metal hazard we cannot see

Homes built before 1978 (US) and before 1992 (Canada) are likely to contain lead paint. Renovating without containment releases lead-laden dust that no air-quality sensor can identify.

Asbestos in older homes: a fiber hazard outside our envelope

Asbestos was used in insulation, popcorn ceilings, vinyl flooring, and roofing through the 1980s. Disturbing it releases microscopic fibers we cannot detect; mesothelioma latency is decades.

COPD and air quality: tighter margins than asthma

Chronic obstructive pulmonary disease affects 16 million US adults. PM2.5 sensitivity is higher than asthma, exacerbations are more dangerous, and indoor recovery matters more.

Migraines and air quality: triggers the dashboard can show

VOC bursts, pressure drops, drowsiness from elevated CO₂ preceding a migraine: the dashboard can document triggers a person knows but cannot prove.

Sleep apnea and air quality: humidity, mites, and overnight CO₂

OSA outcomes interact with bedroom-overnight conditions. The right humidity, low dust-mite allergen, and adequate ventilation can improve CPAP comfort and reduce AHI.

Mental health and air quality: an emerging literature

Recent research links chronic PM2.5, VOCs, and indoor CO₂ to depression, anxiety, and cognitive performance. The data is suggestive, not yet prescriptive.

Formaldehyde (HCHO): why Terrestream does not measure it

Formaldehyde (HCHO) is the most asked-about specific VOC. The Terrestream SEN66 does not measure, report, or detect it - do not use the device to check for formaldehyde. If you suspect it, get a dedicated test or professional advice.

Benzene: why Terrestream does not measure it

Benzene (C₆H₆) is IARC Group 1, present in vape aerosol, traffic, attached garages, and wildfire smoke. The Terrestream SEN66 does not measure, report, or detect it - do not use the device to check for benzene. Only speciated lab testing can identify it; if you suspect benzene, seek professional testing or advice.

Ammonia and agriculture: the rural PM2.5 story behind the outdoor card

NH₃ from livestock and fertilizer is a major PM2.5 precursor. The outdoor feed does not carry ammonia itself; what the dashboard shows is the resulting outdoor PM2.5, from the Google Air Quality API or, when Google's reading is more than three hours old, from Open-Meteo.

Plants as air purifiers: the NASA 1989 myth

A famous study tested potted plants in sealed chambers. Real-world rooms have orders of magnitude more air; the practical contribution is negligible. Have plants because you like them.

Evaporative coolers ("swamp coolers"): cool air, high humidity

Common in the desert Southwest, evaporative coolers add 20-40 grains of moisture to the air for every degree of cooling. Different dynamics than AC, and a different humidity playbook.

Reducing CO₂ indoors: the ventilation ladder

CO₂ is what people exhale. The only durable answer is moving more outside air in. First find out why it stays high, then work the cost-ordered ladder, from free to capital project.

Reducing NO₂ and NOₓ indoors: source elimination first

Indoor NOₓ comes from combustion. The intervention hierarchy starts with eliminating sources and ends with capture-and-exhaust for what remains.

Reducing PM2.5 indoors: filtration plus source control

Two levers: stop making fine particles, and remove them when they appear. Start by asking whether the particles come from outside or from a source in the room.

Reducing PM10 indoors: cleaning regime more than filtration

PM10 settles faster than PM2.5 and is more about deposited dust than airborne particles. Walk-off mats, damp methods, and HEPA-vacuuming carry most of the load.

Reducing VOCs indoors: substitution before mitigation

VOCs are easiest to manage by not introducing them. When you cannot avoid them, ventilation and bake-out are the durable tools, and a VOC index that won't settle usually has one of four causes.

Reducing indoor humidity: dehumidify, ventilate, repair

The 30–50% RH band is the IAQ sweet spot. Above 60% RH for sustained periods, mold and dust mites become a problem. When humidity is stuck outside the band, four causes cover almost every case.

Raising indoor humidity: winter dryness and how to fix it

Cold outdoor air holds little water; once heated indoors, RH drops below 30%. Static, dry skin, respiratory symptoms, and infection-transmission risk all rise.

Reducing indoor ozone exposure: outdoor-driven, mostly avoidance

Indoor ozone comes mostly from outdoor infiltration on bad-air days. The playbook is window timing, building-envelope sealing, and avoidance of ozone-emitting devices.

Reducing SO₂ indoor impact: outdoor-driven, near industrial

SO₂ is almost entirely outdoor-driven from coal combustion, port shipping, oil refining, and volcanic emissions. The playbook overlaps PM2.5 plus SO₂ specifics.

Ozone: an outdoor pollutant we read but cannot make

Ground-level ozone is the most consequential summertime air pollutant in much of North America. The sensor cannot detect it directly; the dashboard pulls it from Open-Meteo.

Sealing and air tightness: the seal-then-ventilate sequence

A leaky house exchanges air the wrong way: cold drafts, dust infiltration, radon, outdoor ozone. Seal first, then add controlled ventilation. The order matters.

Post-renovation IAQ: bake out, clean up, then move back in

The first thirty days after renovation are the highest-emission window the building will ever see. The right protocol cuts months off the off-gas tail.

Spot ventilation: kitchen and bath exhaust done right

Task-specific exhaust handles the worst pollutant sources at their origin. Sized correctly and ducted to outdoors, it does more than whole-house ventilation can.

Outdoor air feeds: where the outside numbers come from

The dashboard's outdoor card layers several data streams: Open-Meteo for weather and modeled air quality, Google Air Quality for current pollutants and the US EPA AQI while its reading is under three hours old (Open-Meteo's values otherwise), and Google Pollen for pollen forecasts. Here is the pipeline.

Office IAQ: the 4 p.m. conference-room problem

A typical office starts the day near the outdoor CO₂ level and ends it well above 1,000 ppm in the meeting rooms, plus VOCs from cleaning and new furniture and whatever the outdoor air brings in.

Low-VOC finish selection: reading the labels

Green Seal, GREENGUARD Gold, CARB Phase 2, FloorScore: which certifications actually mean low emission, which numbers matter, and where the labels do not help at all.

School IAQ: where children spend a third of their day

Classrooms exceed CO₂ targets routinely, locker rooms add cleaning-product VOCs, older buildings have mold, and the school bus idles ten feet from the intake. A separate environment from home, with its own problems.

IAQ on a budget: best impact per dollar, in order

You do not need an HRV and three air purifiers to improve indoor air. The first $0 to $200 of effort delivers most of the gains. Here is the ladder, ordered by impact per dollar.

IAQ tradeoffs with energy: ventilation has a heating bill

Every cubic foot of outside air you bring in is air you have to heat or cool. In some climates "just open windows" is correct; in others it is the most expensive intervention you can pick.

Basement IAQ: a different environment from the rest of the house

Basements run cooler, more humid, and lower-ventilated than the floors above. The HVAC lives down there, the water heater lives down there, and so do the paint cans, the radon, and most of the mold problems.

CO₂ rebreathing detection: when a room is breathing itself

A near-linear CO₂ climb that does not decay is the signature of a room rebreathing its own air. The math is straightforward and the pattern is unmistakable on the dashboard.

Cognitive effects of CO₂: the Allen and Satish literature

Two landmark chamber studies (Satish 2012, Allen 2016) show executive function dropping monotonically as CO₂ rises from 550 to 1,400 ppm. The shape, the domains, and the mechanism candidates.

When to call a pro: the IAQ escalation triggers

Most IAQ problems are DIY. A handful are not. Here are the triggers that say "stop, hire a credentialed professional", and how to choose one.

Sensor accuracy and drift: what to expect over time

Accuracy, repeatability, and drift are different things, and each channel in the Sensirion SEN66 behaves differently over the years. Here are the datasheet figures with their conditions, and what to do when a reading looks wrong.

Pesticide drift: when farms are upwind

Pesticide drift is the rural-IAQ analog of wildfire smoke: outdoor-driven, episode-based, and worst during spraying seasons. The playbook is forecast, close, filter.

The indoor/outdoor ratio: one number that tells you what the envelope is doing

For most outdoor-driven pollutants, indoor concentration divided by outdoor concentration is the single most diagnostic number you can work out from your readings. It tells you whether your house is sealed, filtered, or leaking.

Using forecasts: how to act on tomorrow's air

Outdoor forecasts let Terrestream suggest action before a problem arrives, not after: hours ahead for air quality, and a few days ahead for the weather outlook. Here is how the forecast horizon maps to confidence.

Anticipating indoor events: outdoor current + forecast + indoor reading

Each of the three inputs is a signal. Combined, they help anticipate whether an indoor event is about to happen, so you can act before it does.

How confident a Terrestream recommendation is

Terrestream's recommendations come from fixed rules applied to your readings and outdoor data. Here is what the confidence label on a situation means, and what it does not.

Terrestream advises on your air, not your health

The dashboard will tell you about your air. It will not diagnose, prescribe, or speculate about your health. The line between those two is bright and intentional.

When the data itself is unreliable

Sensors fail in a small set of recognizable ways. When a reading looks stuck, Terrestream holds alerts based on it. Here is how to tell a real spike from a glitch.

How the Terrestream sensors actually work

Three sensor packages, six sensing elements, twelve signals. Here is what is inside the device, what each part measures, and the physical reasons it can and cannot do what it does.

Apartment and condo IAQ: when the air problem is in the next unit

In a multi-unit building, your air is your neighbors' air. Cooking, smoking, cleaning chemicals, even fragrances migrate through shared HVAC, plumbing chases, and balcony paths. Here is how that happens and what can actually be done from inside one unit.

Wildfire season preparedness: what to do before the smoke arrives

A wildfire-smoke event runs better when the supplies are already on the shelf and the envelope is already tight. Here is the May-through-September checklist, sized to a typical western-US household.

Gas to electric: the IAQ side of home electrification

Replacing the gas stove with induction, the gas water heater with a heat pump, and the gas furnace with a heat pump removes the three largest indoor combustion sources at once. The IAQ delta is visible on the dashboard; the financial picture has shifted with new federal credits.

CO₂ as an airborne-pathogen proxy: what the ratio actually tells you

CO₂ does not measure pathogens. But CO₂ and exhaled pathogen droplets share a source (occupants) and a sink (ventilation), so the indoor-to-outdoor CO₂ ratio tracks the fraction of air in the room that other people have already breathed. This is why the Aranet model was widely adopted for ventilation monitoring during the pandemic.

Stack effect and pressure differentials: the building physics that moves your air

Warm air rises, cool air falls, and exhaust fans push the balance around. The result is that pollutants move through a building in predictable directions, the basement supplies the bedrooms more than you think, and a bath fan can backdraft a water heater. The dashboard makes the patterns visible.

New-build vs old-house IAQ: two different problem sets

A tight 2020 build and a leaky 1925 farmhouse fail in opposite directions. The dashboard signatures are different, the priorities are different, and "better" depends on what you are trying to solve.

Microplastics in indoor air

Your clothes shed plastic. So does your carpet, your bedding, and your packaging. The dashboard's PM channels see the bigger fragments as a subset of total particles; the science on health impact is still arriving.

PFAS in indoor dust: the forever-chemical exposure route the dashboard does not see

PFAS exposure indoors is dominated by dust ingestion and dermal contact, not by inhalation. The SEN66 cannot detect them; reducing PFAS load is a housekeeping and procurement problem, not a sensor problem.

Mattress and bedroom off-gassing: the one room where it matters most

You spend a third of your life within a foot of a polyurethane foam slab. The "new mattress smell" is a measurable VOC emission curve, and it lasts longer than the marketing suggests.

Humidifier bacterial risks: Legionella and the white-dust problem

A neglected ultrasonic humidifier aerosolizes whatever is in its reservoir, including bacteria. This is the one IAQ device where maintenance is a life-safety issue, not a comfort one.

Carpet versus hard floor, from an indoor-air-quality view

The blanket "carpet is always bad for IAQ" rule does not survive contact with the data. Quality, age, maintenance, and what is under the floor matter more than the category.

What a 3D printer is putting into your air

Hobby 3D printing emits ultrafine particles and VOCs that scale with filament chemistry and bed temperature. The dashboard sees it; here is what is happening and how to print without exposure.

Woodworking shop air quality at home

Sawdust from oak and walnut is an IARC Group 1 carcinogen for occupational woodworkers. The hobby shop in your garage deserves the same controls; the dashboard will tell you whether they are working.

Air quality is not distributed equally, and the indoor sensor cannot fix that

Outdoor PM2.5 and NOx sit higher near highways, near ports, near industrial sites, and downwind of all three; those locations correlate with race and income in the United States and Canada in ways that are not accidents.

Working out at home: respiratory rate is the multiplier

During hard exercise you move three to ten times more air through your lungs than at rest. Whatever is in that air gets the same multiplier. Home gyms and yoga rooms deserve their own ventilation plan.

Should I bring a sensor to an Airbnb or VRBO?

Vacation rentals are someone else's indoor environment with someone else's cleaning routine, ventilation choices, and smoking history. A portable sensor turns that opacity into one hour of data.

Your commute is part of your exposure, and Terrestream cannot measure it

A fixed indoor sensor cannot follow you into a car cabin, a bus, or a bike lane next to a highway. The exposure that happens on the way to work is real, and it belongs to a different category of instrument.

Infants and indoor air quality

A newborn breathes faster, has smaller airways, and spends almost every hour of every day in the same indoor environment. That makes the nursery's air worth understanding.

Terrestream is not a smoke alarm. Every home needs UL 217 smoke alarms.

Smoke detector vs IAQ monitor: not the same instrument

A common confusion: the sensor on your wall reads PM2.5, and smoke is PM2.5, so it must be a smoke alarm too. It is not. The two devices answer different questions on different timescales, with different consequences for being wrong.

Cleaning up wildfire ash inside the home

Once the air clears outside, the ash that settled on every horizontal surface during the smoke event becomes the next problem. The cleanup protocol matters because dry sweeping puts everything you tried to keep out back into the air.

When the homework gets harder at 4 PM, check the CO₂

A closed bedroom can accumulate CO₂ during homework. The dashboard can help you check ventilation; it cannot establish why a child is having trouble focusing.

Mask selection: N95 vs KF94 vs surgical vs everything else

A particle-filtering respirator is the one piece of protection a HEPA at home cannot give you. Here is what each rating means and when each one is the right tool.

PM sensor accuracy and aerosols

Optical PM sensors estimate mass from scattered light. They are powerful for building telemetry, but aerosol chemistry and particle shape still matter.

VOC Index vs TVOC

VOC Index is a relative signal from a MOX gas sensor. TVOC is a concentration-style lab concept. They measure different things.

NOx Index vs NO₂

NOx Index is a combustion-pattern signal. It is not a regulatory NO₂ concentration measurement.

CO₂ sensor accuracy and ventilation

CO₂ is the clearest occupancy and ventilation signal in most rooms, but placement, calibration assumptions, and recovery time still shape the interpretation.

Pressure context and infiltration

Pressure is not an IAQ compliance channel. It is building-physics context that helps explain when outdoor air, weather, and HVAC operation are shaping indoor readings.

Lux and indoor-air context

Lux helps interpret placement, daylight, display behavior, and occupancy patterns. It is not proof of circadian lighting performance or WELL lighting compliance.

Commercial IAQ monitoring for schools

Schools need room-level evidence: CO₂ for ventilation, PM recovery for filtration, humidity for comfort and building risk, and source patterns that facilities teams can act on.

Factory and light-industrial IAQ monitoring

Light-industrial spaces need pattern visibility around dust, combustion, solvents, ventilation, and maintenance. IAQ monitors support triage; they do not replace occupational hygiene instruments.

The Tuesday-morning fan sound

A brief fan sound on the first Tuesday of the month is normally the SEN66 sensor self-clean cycle.

Quiet hours, brightness, and sound

Use Quiet Hours and device/app settings to reduce display, light, and sound behavior on a schedule.

Factory reset your device

Factory reset clears saved device configuration, claim, and account-linking information so the sensor can be paired again. Do it before you sell, give away, or recycle the device.

Compare indoor air-quality monitors

A fair, sourced buyer guide to Terrestream, AirGradient ONE, Ruuvi Air, Awair Element, Airthings View Plus, Aranet4 HOME, Kaiterra Sensedge Mini, and IQAir AirVisual Pro.

Terrestream vs Awair Element

Awair Element is a compact five-factor monitor; Terrestream adds broader particulate sizing, NOx, pressure, light, and deeper interpretation.

Terrestream vs Airthings View Plus

Airthings View Plus is compelling when radon is central; Terrestream emphasizes multi-signal indoor behavior and local-friendly workflows.

Terrestream vs Aranet4 HOME

Aranet4 HOME is a focused portable CO₂ monitor; Terrestream is a broader room air-quality system.

Terrestream vs IQAir AirVisual Pro

IQAir AirVisual Pro emphasizes PM2.5, CO₂, AQI, and a large color display; Terrestream adds more indoor channels and source interpretation.

Terrestream vs AirGradient ONE

AirGradient ONE is an open-home indoor monitor with strong local-home appeal; Terrestream emphasizes polished room interpretation, commercial evidence, and buyer-ready guidance.

Terrestream vs Ruuvi Air

Ruuvi Air is a credible open-friendly SEN66 monitor; Terrestream emphasizes Wi-Fi-direct operation, a touchscreen display, outdoor-data fusion, and US buyer readiness.

Terrestream vs PurpleAir

PurpleAir is strongest as a particle and outdoor-map ecosystem; Terrestream is built for indoor room decisions across particles, gases, comfort, context, and recommendations.

Terrestream vs Apollo AIR-1

Apollo AIR-1 is a compact ESPHome/Home Assistant monitor with strong local-control appeal; Terrestream emphasizes a finished room device, broader buyer guidance, and included cloud intelligence.