Why a healthier home starts with understanding.
Home health comes down to exposure — the air you breathe, the water you drink, and everything your skin touches, thousands of times a day, in the place you spend most of your life. Nestwell connects your home’s environmental health to clear, personalized next steps — from air & water quality to mold, moisture, soil, and property risk.
County-level emissions, radon zones, and nearby toxic-release and Superfund sites.
Certified lab results for metals, PFAS, and mold in your air, water, dust, and soil.
Your biological response over time, as exposures change through critical windows.
Everything your body meets, over a lifetime.
How does exposure to chemicals in the water, air, and soil influence health outcomes ranging from asthma to diabetes to fertility? The exposome1,2 is a framework for studying and understanding the lifetime of lifestyle, chemical, and psychosocial exposures that you come into contact with every day.
Why does home health matter?
You spend over half your life in your home, but there can be a variety of hidden environmental factors that are silently contributing to the development of disease over a lifetime. In fact, indoor air quality is often worse than outdoor air.3–5
Your physical health matters. But so does everything around it.
While your own body and health play a major role in how you feel, the exposome has been implicated in the development of diseases across biological systems such as asthma, heart disease, and developmental disorders. Thus, understanding the environmental drivers of disease you come into contact with every day is paramount for mitigating disease.
Measurements of the exposome range from air pollution metrics6 and targeted chemical measurements7 to broad measurement of all compounds in the blood8 to broad survey questions9 that have all been validated and associated with the development of disease across time. These measurements have different levels of confidence in the specific exposures measured. However, all measurements attempt to identify exposure to a chemical during a critical window10–12 such as childhood, pregnancy, or old age.
Where you live shapes your health as much as how you live.13
It’s a familiar idea — but what factors beyond social determinants of health are driving the development of disease in different populations? Environmental drivers. At Nestwell, we collect data from trusted sources including the US Environmental Protection Agency, the CDC, and the Environmental Working Group to give you a sense of the exposures in your area.
Bridging the Gap Between Outdoor and Indoor Risk
Geospatial data sources and what each tells us. Tap to expand.
Five EPA datasets anchor the community layer of your assessment:
The EPA's comprehensive count of air pollutant emissions, compiled county by county. We use it to break down which pollutants — and which sources, like on-road traffic — drive your local air quality.
A county-level geological estimate of radon potential, rated 1 to 3. It tells you the baseline risk for your area, though radon still varies house to house.
A public database of facilities that release or manage toxic chemicals. We surface the reporting sites nearest your property so you can see what's operating in your area.
The EPA's registry of the nation's most contaminated sites and their cleanup status. Proximity to a Superfund site is a signal for elevated soil and groundwater risk.
The EPA-led real-time air quality index, drawn from a national network of regulatory monitors. It keeps your air picture current — reflecting today’s conditions, including smoke, not just a seasonal average.
Percentile-based, benchmarked against homes nationwide. Illustrative data shown.
A single, comparable read on your home.
At Nestwell, we believe you should always know how your home compares to other homes in the country, and what actions you can take to mitigate its risks. The Nestwell Score gives you a baseline understanding of the potential environmental hazards surrounding your home.
To do this, we use a set of simple percentile-based metrics that place you and your home in a distribution of all other measurements in the country — for air quality, specific air pollutants, chemicals in your water such as PFAS, and many more. We average those together to get a full idea of your home’s environment. From there, we find the number of location-based hazards in your area including toxic release inventory sites, Superfund sites, and brownfields, and use that to inform your overall score.
Together, this score is further influenced by live events in your area, giving you the industry’s most up-to-date view of current hazards — including wildfire alerts, smoke and air-quality alerts, and exposure events from federally mandated reporting channels.
Your baseline, kept current.
Environmental conditions around your home change daily. Air quality changes with the weather, or smoke drifts in from hundreds of miles away. A new NWS alert means something in your air or weather pattern has shifted. These insights and more are provided in real time in your dashboard. Your Nestwell Score captures your baseline, but the Insights map keeps you current.
Available to members, the live Insights map layers real-time and near-real-time data directly over your property: EPA AirNow air quality readings, active National Weather Service alerts, NIFC wildfire perimeters, US Drought Monitor status, USGS seismic activity, and EPA Toxic Release Inventory facilities in your area — all surfaced as soon as the alert reaches the system. A “Right now” strip at the top of the map distills it to the signals that matter most: current AQI, any active alerts, drought class, and nearby fire activity.
See your home’s live map →Your score is a starting point. A test is the truth.
Where to look
Built from your address, your home’s characteristics, and authoritative regional data — air, water, radon, and nearby hazards. A directional estimate that shows you where the risk most likely is.
What’s true
A certified lab measures what’s actually in your air, water, dust, or soil — the real reading for your specific home, not a regional average.
Some exposures can only be found inside your own home.
Despite the rich information geospatial data provides, and all the potential impacts on health outcomes being measured in these ways, there is a wide variety of information that can only be obtained through direct measurement of exposures in your own home. At Nestwell, we bridge that gap with certified lab results from our partners that can measure a wide variety of exposures including metals, PFAS, and mold in your home’s air, water, dust, and soil. By testing your own home, you can identify direct sources of exposure and take steps to remediate it, keeping your family safe.
How your home’s sample becomes a report
The sample from your home is mailed to a certified lab and analyzed under a harmonized protocol.
Sample your air, water, dust, or soil with a guided Nestwell kit.
Your sample ships to a certified partner lab in prepaid packaging.
Analyzed under a harmonized protocol across our lab network.
Results fold into your Nestwell Score with clear next steps.
The Three Thresholds.
A lab report looks like a list of chemicals and numbers. It is really a set of comparisons.
Every reading is measured against a floor and a ceiling. The floor belongs to the instrument: there is a smallest amount it can detect at all, called the method detection limit, and a slightly higher amount it can measure precisely enough to put a number on, called the reporting limit. The ceiling is a health judgment: the level at which certain health authorities say the amount starts to matter.
We keep those two apart on your report, and this is how to read the space between them.
One reading, read three ways
Use the buttons to see how the same contaminant is reported at three different levels. Zones are drawn at equal width so the boundaries stay readable. The bar shows which side of a line you land on, and the numbers underneath carry the true magnitude.
41× the limit.
The reading exceeds the published limit for this contaminant. The bar shows you which side of the line you are on; the multiple underneath tells you by how much, because a bar drawn to scale at 41× would be unreadable.
The three numbers
Determined by running low-level samples repeatedly until the lab can show, statistically, that a signal at that level is real and not noise. Below the MDL, the instrument cannot tell the difference between a trace of a contaminant and the background hum of the machine.
Set above the MDL, commonly three to five times higher, at the level where the measurement is not just detectable but quantifiable. It is the boundary between “not detected” and a number on your report. It belongs to the method and the sample type, not to the chemical: lead comes back at 0.005 PPM in water and at 20 mg/kg in soil, from the same lab, on the same day.
A health or regulatory judgment, not a measurement. This is the only one of the three that says anything about risk, and it is the only one that can move without the lab changing a thing. When an agency revises a standard, your old reading gets re-read against the new number.
We look across regulatory bodies and health research for strict limits.
For every contaminant we can test, we have published limits from federal regulators, state programs, and independent health researchers. A single chemical often has several: a legal maximum, an action level, a health-based guideline set far lower. Your reading is compared against the strongest limit that exists for it.
Plenty of contaminants have never been assigned a limit by anyone. When we measure one and find it, we show the number and say exactly that: present, with no published limit to compare it against.
- Primary MCLLegal
The federally enforceable maximum for a contaminant in drinking water, set by the EPA under the Safe Drinking Water Act.
- Action levelLegal
The concentration that triggers required treatment or corrective action. It is how lead and copper are regulated, rather than by a straight maximum.
- Treatment techniqueLegal
An enforceable required process where a contaminant is impractical to measure directly at the tap.
- Secondary MCLAesthetic
A non-enforceable federal guideline for taste, odour, colour, and staining. Exceeding one is a nuisance, not a health finding, and we label it that way.
- Health guidelineAdvisory
A health-based level from an independent research body or a state programme, often far below the legal limit, published without the cost-and-feasibility weighting.
- ReferenceAdvisory
A published comparison value where nothing stronger exists: a typical background range, or a level used in the literature.
Only the first three are legal limits. Anything below that line is labelled on your report as advisory or aesthetic, never as a standard you are violating.
What actually happens to your sample.
Your kit goes to an accredited partner lab and is analysed under a documented, method-specific protocol. Each method fixes the preparation, the instrument, the calibration, and the quality checks: EPA 200.8 for metals, EPA 537.1 for PFAS, and others by analyte class.
Your sample is checked against its paperwork, timestamped, and given a lab ID. Hold time and preservation are verified. A water sample that arrived warm or late gets flagged, because both change the result.
Metals are digested in acid to free them from anything they are bound to. Organics are extracted into a solvent and concentrated. This step is what turns a bottle from your tap into something an instrument can read.
The prepared sample is run through an instrument matched to the analyte class: mass spectrometry for metals, chromatography paired with mass spectrometry for organics and PFAS, culture plates for bacteria.
Before your sample runs, the instrument reads a series of standards of known concentration to build a calibration curve. Your sample’s signal is converted to a concentration by where it falls on that curve, which is also why the curve’s lowest point sets your reporting limit.
Blanks catch contamination introduced by the lab itself. Spiked samples confirm the method recovers a known amount. Duplicates confirm the result repeats. If the QC fails, the batch is re-run, including your sample.
The lab issues the values with their reporting limits and methods attached. We match each analyte to its limits, classify it, and write it into your report and your Nestwell Score.
Four things a result does not mean
It means below the reporting limit for that method. A more sensitive method may find it.
Limits are evidence based, but research is always evolving. For some contaminants there is no level anyone considers ideal.
Water chemistry changes with season, use, and plumbing. Air and dust change with the weather and the day. Re-testing can turn a single reading into a more detailed trend.
It is a reason to confirm the source and act on it. Your report tells you which of those two comes first.
Your Exposome Over Time
An important part of the exposome is your body’s biological response to the environment. Because each person has a unique combination of biology, lifestyle, and experiences, the same exposure can affect people differently.24
As your environment and daily habits change over time, so does your exposome — making it a dynamic picture of your health. Nestwell gives you the opportunity to monitor exposures in your area, and to test your home’s exposures over time so you understand the effectiveness of your chosen interventions.
Grounded in peer-reviewed science.
Integrating exposomics into biomedicine
The exposome complements the genome — measuring the environmental half of disease risk that DNA alone can’t explain.1,2
An atlas of exposome–phenome associations
Large-scale studies map specific exposures to specific health and disease outcomes across the population.7,9
Critical windows of exposure
Exposures during childhood, pregnancy, and later life carry outsized, lasting effects on lifelong disease risk.10–12
Our Advisory Team
Nestwell is grounded in peer-reviewed science and a panel of experts across institutions such as Stanford and UCSF. They are experts across medicine and environmental health who help guide Nestwell to properly test your home for environmental exposures and link those to potential health outcomes.
Questions, answered.
Both. We evaluate contaminants against federal legal limits (like EPA Maximum Contaminant Levels) and, where the science has moved faster than regulation, against independent health-based guidelines such as the Environmental Working Group’s — which are often stricter. That’s why a home can be perfectly “legal” and still worth addressing.
References
- 1.Miller, G. W. & Banbury Exposomics Consortium. Integrating exposomics into biomedicine. Science 388, 356–358 (2025).
- 2.Wild, C. P. Complementing the genome with an 'exposome': the outstanding challenge of environmental exposure measurement in molecular epidemiology. Cancer Epidemiol. Biomarkers Prev. 14, 1847–1850 (2005).
- 3.US EPA, O. Indoor Air Quality. US EPA https://www.epa.gov/report-environment/indoor-air-quality (2017).
- 4.Dris, R. et al. A first overview of textile fibers, including microplastics, in indoor and outdoor environments. Environ. Pollut. 221, 453–458 (2017).
- 5.Leung, D. Y. C. Outdoor-indoor air pollution in urban environment: challenges and opportunity. Front. Environ. Sci. 2, 119805 (2015).
- 6.Pope, C. A., 3rd, Ezzati, M. & Dockery, D. W. Fine-particulate air pollution and life expectancy in the United States. N. Engl. J. Med. 360, 376–386 (2009).
- 7.Patel, C. J., Ioannidis, J. P. A. & Manrai, A. K. An atlas of exposome–phenome associations in health and disease risk. Nat. Med. 1–10 (2026) doi:10.1038/s41591-026-04266-0.
- 8.Petrick, L. M. & Shomron, N. AI/ML-driven advances in untargeted metabolomics and exposomics for biomedical applications. Cell Rep. Phys. Sci. 3, 100978 (2022).
- 9.Lloyd, D. et al. Questionnaire-based exposome-wide association studies for common diseases in the Personalized Environment and Genes Study. Exposome 4, osae002 (2024).
- 10.Nelson, C. A., 3rd & Gabard-Durnam, L. J. Early adversity and critical periods: Neurodevelopmental consequences of violating the expectable environment. Trends Neurosci. 43, 133–143 (2020).
- 11.Giulivo, M., Lopez de Alda, M., Capri, E. & Barceló, D. Human exposure to endocrine disrupting compounds: Their role in reproductive systems, metabolic syndrome and breast cancer. A review. Environ. Res. 151, 251–264 (2016).
- 12.Barouki, R., Gluckman, P. D., Grandjean, P., Hanson, M. & Heindel, J. J. Developmental origins of non-communicable disease: implications for research and public health. Environ. Health 11, 42 (2012).
- 13.Chetty, R. et al. The association between income and life expectancy in the United States, 2001-2014. JAMA 315, 1750–1766 (2016).
- 14.US EPA, O. National Emissions Inventory (NEI). US EPA https://www.epa.gov/air-emissions-inventories/national-emissions-inventory-nei (2015).
- 15.US EPA, O. The EPA Map of Radon Zones. US EPA https://www.epa.gov/radon/epa-map-radon-zones (2014).
- 16.US EPA, O. Toxics Release Inventory (TRI) Program. US EPA https://www.epa.gov/toxics-release-inventory-tri-program (2013).
- 17.US EPA, O. Superfund. US EPA https://www.epa.gov/superfund (2014).
- 18.AirNow.gov. https://www.airnow.gov/
- 19.National Weather Service. Fire Weather. NOAA's National Weather Service https://www.weather.gov/box/fire (2025).
- 20.National Risk Index for Natural Hazards. https://www.fema.gov/flood-maps/products-tools/national-risk-index
- 21.Environmental Working Group. EWG's Tap Water Database: What's in Your Drinking Water? https://www.ewg.org/tapwater/
- 22.The U.S. Drought Portal. Drought.gov https://www.drought.gov/
- 23.Home. USGS https://www.usgs.gov/
- 24.Niedzwiecki, M. M. et al. The exposome: Molecules to populations. Annu. Rev. Pharmacol. Toxicol. 59, 107–127 (2019).
- 25.National Interagency Fire Center. Wildland Fire Open Data — current wildfire perimeters. https://data-nifc.opendata.arcgis.com/
- 26.Prüss-Ustün, A. et al. Preventing disease through healthy environments: a global assessment of the burden of disease from environmental risks. World Health Organization (2016).
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