A plain-language guide to what we measure, what the colors mean, how air and water affect your health, how the laws that govern pollution work, and how it all ties to climate.
West Virginia's ridges and river valleys trap air. On calm nights, cooler air settles into the valleys and forms a temperature inversion, a lid that holds pollution near the ground until the next day's sun or wind mixes it out. Add traffic, wood and coal home heating, and heavy industry along the river corridors (the Kanawha Valley's "Chemical Valley" stretch is a well-known example) and the same spot can read clean at midday and hazy by dawn.
Our own sensors show it: along the industrial corridor, fine particles build up overnight (roughly 1.4–2× the daytime level) while an upriver control site stays flat. Smoke can also drift in from far away, and regional wildfires have pushed WV into "unhealthy" days. Dense, always-on community sensors are exactly what it takes to catch these local, hour-by-hour swings that a handful of official monitors can miss.
Particles 2.5 micrometers or smaller, about 30× thinner than a hair. They come from anything that burns: vehicles, industry, wood stoves, wildfires. Because they're so small they slip deep into the lungs and into the bloodstream, which is why PM2.5 is the pollutant most tied to health effects. It's the number our map is colored by.
Bigger particles up to 10 µm: road and construction dust, pollen, mold. Irritating to eyes, nose, and throat, and hard on people with asthma.
The smallest fraction we report: largely combustion-related and useful for spotting fresh smoke or exhaust.
Gases released by fuels, solvents, and many industrial processes; often what you smell. Our community sensors report a single relative gas index — good for spotting changes and odor events, not a calibrated measure of any specific compound.
Ground-level ozone isn't emitted directly. It forms in sunlight when VOCs and nitrogen oxides react, so it peaks on hot, sunny afternoons. It irritates the lungs and worsens asthma. Community PurpleAir sensors can't measure ozone, so we pull it from EPA AirNow reference monitors — a sparser, reference-only layer you can chart on the Air page.
"VOC" is an umbrella for hundreds of carbon-based gases. Our low-cost sensors can't tell them apart; they report one combined index. But the individual compounds behind that number matter a lot for health, and EPA's air-toxics network measures many of them one by one. Common ones in industrial and traffic settings:
To be clear about the hardware: the PurpleAir units in this network sense gases with a low-cost metal-oxide (MOX) gas sensor (a Bosch BME680-class chip). It doesn't identify molecules — its surface resistance changes in the presence of reducing gases as a group: many VOCs (alcohols, aldehydes, ketones, aromatics like the BTEX above) plus things like carbon monoxide and hydrogen. What comes out is one relative "gas resistance" number, sensitive to temperature and humidity, reported as a single index.
Every dot on our map is colored by the U.S. EPA's Air Quality Index categories for PM2.5 (µg/m³):
| Good | 0–12 | Air is satisfactory; little or no risk. | |
| Moderate | 12–35 | Acceptable; unusually sensitive people should watch how they feel. | |
| Unhealthy for sensitive groups | 35–55 | Kids, older adults, and people with heart/lung conditions should ease up on strenuous outdoor activity. | |
| Unhealthy | 55–150 | Everyone may feel effects; sensitive groups more so. Limit prolonged exertion outdoors. | |
| Very unhealthy | 150–250 | Health alert — avoid outdoor exertion. | |
| Hazardous | 250+ | Emergency conditions; stay indoors with clean air. |
🔍 Not feeling right and wondering what's around you? Try What's near me?: share your location and any symptoms, and it maps the wells, facilities, discharges, and spills nearby, flagging the ones that fit how you feel.
Children, adults over 65, pregnant people, and anyone with asthma, COPD, or heart disease feel air pollution first and hardest. Symptoms can include coughing, throat and eye irritation, shortness of breath, and tightness in the chest.
Ground-level ozone is a lung irritant that forms on hot, sunny afternoons. It can trigger asthma, tighten the chest, and inflame airways even in healthy people, which is why "code orange/red" ozone days matter most for kids and anyone with lung disease.
VOCs are a mixed bag: some (like benzene and formaldehyde, common around oil & gas) are known human carcinogens; others mainly cause short-term headaches, dizziness, and eye/throat irritation. Our community VOC reading is a relative gas index — it can flag that something is off, but not which chemical or at what concentration. Persistent VOC odors near a facility or well are worth reporting so they can be looked at properly.
West Virginia's thousands of abandoned and orphaned gas wells can leak raw natural gas and hydrogen sulfide (H2S), a toxic gas with a rotten-egg smell. This is the issue behind the Rutledge neighborhood in Charleston, and a founding reason communities here started monitoring their own air. (Turn on the 🛢️ Abandoned wells map layer to see the wells near you, orphans in red.)
⚠️ Raw natural gas is odorless. The "gas smell" you know from a kitchen stove is a chemical (mercaptan) that utilities add on purpose so you can detect leaks. Gas venting straight from a well has no such additive — it's mostly methane, which is colorless and has no smell. So a leaking well can be releasing gas you'll never notice by nose. That's exactly why an air monitor matters: our community VOC index responds to the hydrocarbons your senses can't, giving a signal where there'd otherwise be none. (H2S, when it's in the mix, does smell — but see below.)
The dangerous part: you can smell H2S at very low levels, but at higher concentrations it deadens your sense of smell within minutes, so the smell going away does not mean the gas is gone. Never treat "I don't smell it anymore" as safe.
What to do: if you smell persistent gas or rotten eggs, don't ignore it. Get to fresh air, and for a strong or sudden smell call 911 (or your gas utility's emergency line). Then put it on the map: click the well and 🚨 report the problem →, and see the Events page for the plugging backlog.
The Water page tracks measured stream chemistry, coal-mine discharges, and Safe Drinking Water Act violations by system. Here's why those numbers matter for your body:
If your water looks, smells, or tastes off, contact your water system and report it →. For a boil-water advisory, follow your utility's guidance.
Most West Virginians drink surface water — rivers and streams — not well water. Charleston's tap water, for example, comes primarily from the Elk River, treated at West Virginia American Water's Kanawha Valley plant, and that supply ultimately depends on thousands of small mountain streams upstream. Because the intake sits on a river, whatever happens upstream reaches your tap. That's exactly what the 2014 Freedom Industries spill exposed: the leak was barely a mile and a half above the intake, and 300,000 people lost usable water within hours. Knowing your source, and what sits upstream of the intake, is the first step in protecting it.
Many older WV towns (including parts of Charleston) still have combined sewers that carry stormwater and sewage in the same pipe. In dry weather it all goes to treatment, but during heavy rain the system overflows by design, discharging untreated sewage straight into the river (a "combined sewer overflow," or CSO). That's an aging- infrastructure problem, not a single bad actor, and it's a major reason river bacteria spike after storms. Fixing it is a systems question, one worth understanding alongside individual polluters.
It depends on where and when. In urban stretches like the Kanawha, the main swimming risk usually isn't a chemical — it's bacteria (E. coli) from sewage and runoff, which spikes for a day or two after rain (see CSOs above); high E. coli signals fecal pollution and possible pathogens. Charleston Waterkeeper runs a volunteer Swim Alert program that samples bacteria and posts whether it's safe: the best local guide. Rules of thumb: avoid water-contact recreation for ~48 hours after heavy rain, steer clear of stretches right below industrial outfalls, and heed any WV DEP advisory.
Often yes, in moderation, but check the advisory first. WV publishes a Sport Fish Consumption Advisory: the statewide baseline is no more than one meal per week of most sport fish (rainbow trout excepted), and for some species in some waters (certain bass, catfish) as few as one or two meals per month. The limits are driven mostly by mercury (widespread — it falls from the air, partly from coal, and builds up in fish) and by PCBs and dioxin (more localized, legacy industry). Children and pregnant people should be most cautious. Check the current, water-specific advisory: WV DHHR fish advisories.
WV DEP's Integrated Report flags a stream as "impaired" (the Clean Water Act 303(d) list) when it fails a water-quality standard for one of its designated uses: drinking, recreation, or aquatic life. Crucially, a stream can be listed for one specific reason (bacteria, low pH from acid mine drainage, iron, sediment, or "biological" impairment) while being fine for others. So "impaired" doesn't mean "toxic everywhere" — it means "fails a specific standard for a specific use." A lot of WV segments are listed, largely from historic mining and old infrastructure; that's the case for cleaning them up, not for writing them off.
They're not separate problems. The same facilities often hold both air and water permits. Mercury emitted into the air settles into rivers and accumulates in fish, which is why an air pollutant drives fish advisories. Rain washes air pollution and land contamination into streams. And the same valleys that trap air pollution (see Basics) tend to concentrate the industry that affects both. Watching air and water together — as this project does — gives a fuller picture than either alone.
Low-cost community sensors give us dense, real-time coverage that the sparse network of regulatory monitors can't. The trade-off is precision: they can read a little high, especially in humidity. So we continuously compare each community sensor against the nearest EPA reference monitor and apply a standard EPA correction; you can see all of that on the Air page's validation panel. For official air-quality information, see AirNow.gov.
Our PM2.5 numbers can be validated and corrected against EPA monitors. VOC cannot. The EPA reference monitors we use measure only PM2.5 — no VOC — so there's nothing to calibrate our community VOC against. And the community VOC is a relative index (a single gas-sensor number), not a concentration. Treat VOC as community-only and directional: great for spotting a change or an odor event, not for an exact value or a specific compound.
Plain-language education, not legal advice. Specifics vary — verify with WV DEP and EPA.
The federal Clean Air Act (1970, major amendments 1977 & 1990) is the backbone of U.S. air regulation. Key pieces:
A facility that emits above certain thresholds generally can't build or operate without a permit, a legally binding document that sets its limits and obligations:
Permits are public records, usually with a public-comment period before they're issued. They're where the abstract law becomes a concrete number a specific plant must stay under.
A violation is a failure to follow the law or a permit. For example:
Violations surface through inspections, a facility's own required reports, or monitoring data. Regulators can respond with a Notice of Violation, a consent order, civil penalties/fines, or — for knowing, serious harm — criminal charges. You can look up a facility's compliance and enforcement history on EPA's ECHO database.
The Clean Water Act (1972) governs pollutant discharges into rivers, streams, and other "waters of the United States":
Air and water permits aren't the whole story. A separate set of laws governs the chemicals themselves: making them, storing them, dumping them, and cleaning them up:
Beyond health, contamination has real effects on the environment and on what you own:
This is plain-language education, not legal advice. For your situation, talk to WV DEP/EPA and, for private claims, a licensed attorney.
One of the six pollutants with a national health-based limit (NAAQS).
A hazardous air pollutant (e.g., benzene) on EPA's separate 180+ list.
A single identifiable source of pollution — a smokestack or a discharge pipe.
The maximum amount of a pollutant a facility may discharge to water.
Notice of Violation: a formal finding that a facility broke a rule or permit.
Toxics Release Inventory — public data on facilities' reported chemical releases (the basis of our Sources page).
The federal program that funds and forces cleanup of contaminated sites.
The law governing how hazardous waste is stored, hauled, and disposed of — "cradle to grave."
A lawsuit the Clean Air/Water Acts let ordinary people file against a violator (after notice).
Climate isn't only a global story — it shows up in the records we keep right here. Below is the year-by-year ground-level ozone from the EPA reference monitors we archive for WV. Ozone forms faster in heat and sunlight, so it's a local fingerprint of hotter summers as much as of emissions.
Most of what harms local air also drives climate change. Both come from the same smokestacks and tailpipes. Burning coal, oil, and gas releases the health pollutants we track (fine particles, sulfur dioxide, and nitrogen oxides) and the gases that warm the planet (carbon dioxide and methane). That overlap is good news: cutting fossil-fuel pollution cleans the air you breathe today and slows warming. Scientists call this a co-benefit.
Greenhouse gases trap heat in the atmosphere. The main ones are CO₂ from burning fossil fuels and methane from gas systems, coal, and agriculture. Human activity has already warmed the planet about 1.1–1.2 °C above pre-industrial levels, driving more extreme heat, heavier rainfall and flooding, and longer wildfire seasons, including the Canadian wildfire smoke that reached West Virginia (see our Events page).
Under the 2015 Paris Agreement, nearly every country agreed to hold global warming to well below 2 °C above pre-industrial levels and to pursue efforts to limit it to 1.5 °C. Each country sets its own pledge, called a Nationally Determined Contribution (NDC). Many, including the U.S., have set goals of net-zero emissions by around 2050.
The IPCC, the UN body that synthesizes the world's climate science, is specific about the 1.5 °C path:
Getting there means rapid, deep cuts across every sector: phasing down unabated fossil-fuel use, scaling up renewables and efficiency, electrifying transport and buildings, sharply reducing methane leaks, protecting forests, and removing some carbon that's already been emitted. The IPCC's finding is blunt but hopeful: the tools exist and are increasingly affordable, and the gap is the pace of action. Current national pledges, if met, still leave the world short of 1.5 °C.
West Virginia's economy has long been tied to coal and, now, natural gas, so the energy transition lands harder here than in most places. That also makes the co-benefit unusually concrete. Consider the state's orphaned and abandoned gas wells: roughly 6,300 are officially documented and estimates run past 50,000, many drilled before 1929 and never properly sealed. They leak methane — a potent greenhouse gas — along with the volatile organic compounds and other gases that can foul nearby air. Plugging them slows warming and cleans local air in a single act. The same logic runs through the whole transition: cleaner power, less methane leakage, and efficiency each trim the PM2.5, SO₂, and VOCs that West Virginians actually breathe.
That is why watching our own air matters. In the Kanawha Valley, the industrial corridor around Charleston, a growing community network of low-cost sensors picked up the smoke when drought-driven fires swept the southern coalfields in November 2024 (see our Events page). Tracking local air makes these trade-offs visible and holds the improvements accountable.