Ozone 8-hour 4th-highest daily max
Ozone 8-hour 4th-highest daily max in Connecticut statewide reached 0.075 ppm in 2024, 7% above the EPA NAAQS of 0.07 ppm.
State · TRI 2024
Connecticut Pollution
193 TRI facilities, 504 public water systems, and 17 Superfund / NPL sites across 8 counties. Statewide TRI releases rose sharply year over year (+35%). Toxic releases concentrations have fallen 29% since 2010.
FIPS 09 · population 3,605,944 · 8 counties total
Anomaly engine
Notable Signals At The State Level
TRI water releases
TRI water releases at Connecticut have more than three-quarters since 2010 (through 2024).
TRI air releases
TRI air releases at Connecticut have more than halved since 2010 (through 2024).
Where the burden sits
County-Level TRI Choropleth
A color-shaded map of pollution data. Darker counties report more pounds of toxic chemicals released to the EPA's Toxics Release Inventory (TRI).
Shaded by total reported releases for 2024. Counties without a published page render as “no TRI data”. Red dots mark this state's top emitters.
Statewide pollutant pathways
Connecticut Pollutant Multi-Year Trends
PM2.5 annual mean (NAAQS 9 µg/m³ (annual))Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.
PM2.5 annual mean (NAAQS 9 µg/m³ (annual)) concentrations have more than halved since 2010.
PM2.5 24-hour 98th percentile (NAAQS 35 µg/m³ (24-hour))Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.
PM2.5 24-hour 98th percentile (NAAQS 35 µg/m³ (24-hour)) concentrations have more than halved since 2010.
Ozone 8-hour 4th-highest daily max (NAAQS 0.070 ppm (8-hour))Health riskGround-level ozone (smog) forms when vehicle and industrial emissions react in sunlight. Inflames the airways, triggers asthma attacks, and worsens heart and lung disease.
Ozone 8-hour 4th-highest daily max (NAAQS 0.070 ppm (8-hour)) concentrations have fallen 12% since 2010.
NO₂ annual mean (NAAQS 53 ppb (annual))Health riskA tailpipe and combustion gas. Concentrates near busy roads and industrial sites; raises risk of airway inflammation, asthma, and lower respiratory infections in children.
NO₂ annual mean (NAAQS 53 ppb (annual)) concentrations have fallen 36% since 2010.
Lifetime cancer risk all pollutants (100 in a million (EPA elevated threshold))Health riskEPA-modeled added cancer cases per million residents from a lifetime of breathing local air toxics. EPA flags 100-in-a-million as elevated.
Single-vintage exposure modeling — EPA cadence is multi-year, so no trend line yet.
Formaldehyde ambient mean (0.077 µg/m³ (1-in-a-million URE))Health riskAn air toxic emitted by refineries, wood products, and combustion. EPA classifies it as a known human carcinogen — long-term inhalation raises cancer risk.
Single-vintage exposure modeling — EPA cadence is multi-year, so no trend line yet.
Benzene ambient mean (0.13 µg/m³ (1-in-a-million URE))Health riskAn air toxic from gasoline, refineries, and tobacco smoke. A known human carcinogen — chronic exposure is linked to leukemia and other blood cancers.
Single-vintage exposure modeling — EPA cadence is multi-year, so no trend line yet.
TRI air releases (5.1 fugitive + 5.2 stack)Health riskToxic chemicals reported by industrial facilities as released into the air — fugitive leaks plus smokestack emissions. Higher pounds means more inhaled exposure for nearby residents.
TRI air releases (5.1 fugitive + 5.2 stack) concentrations have more than halved since 2010.
TRI water releases (5.3)Health riskToxic chemicals reported by industrial facilities as discharged to surface waters (rivers, lakes, the ocean). Affects fishing, recreation, and downstream drinking-water intakes.
TRI water releases (5.3) concentrations have more than halved since 2010.
TRI land + off-site releasesHealth riskToxic chemicals released to land on-site or transferred off-site for disposal — landfills, deep-well injection, and similar. Risks groundwater contamination over time.
TRI land + off-site releases concentrations are up 24% since 2010.
Greenhouse gases (GHGRP large emitters, through 2023)Health riskGreenhouse gases reported by large industrial emitters under EPA's GHGRP, in metric tons of CO₂ equivalent. Drives climate warming and the heat-related health effects that follow.
Greenhouse gases (GHGRP large emitters, through 2023) concentrations are up 68% since 2010.
| County | Population | Facilities | Total releases | YoY | Top chemical |
|---|---|---|---|---|---|
| New Haven CountyFIPS 09009 | — | 60 | 882k lb | +105% | Copper compoundsHealth riskInhaled copper fumes cause metal-fume fever; chronic ingestion above EPA's 1.3 mg/L action level damages the liver. (EPA) |
| Fairfield CountyFIPS 09001 | — | 28 | 553k lb | +87% | MethanolHealth riskAcutely toxic if ingested or inhaled. Metabolizes to formaldehyde and formic acid, causing blindness and metabolic acidosis. (EPA) |
| Hartford CountyFIPS 09003 | — | 57 | 392k lb | -27% | Nitrate compounds (water dissociable; reportable only when in aqueous solution)Health riskDrinking-water nitrate causes methemoglobinemia ('blue-baby syndrome') in infants; EPA MCL is 10 mg/L as N. (EPA) |
| Litchfield CountyFIPS 09005 | — | 12 | 71k lb | -32% | Zinc compoundsHealth riskGenerally low acute toxicity. Chronic high-dose exposure disrupts copper absorption and immune function. (ATSDR) |
| Windham CountyFIPS 09015 | — | 12 | 49k lb | +40% | Ozone |
| Middlesex CountyFIPS 09007 | — | 11 | 39k lb | -31% | AmmoniaHealth riskSevere respiratory and eye irritant; high concentrations cause chemical burns to lung tissue. (EPA) |
| New London CountyFIPS 09011 | — | 8 | 24k lb | -10% | StyreneHealth riskIARC Group 2A probable carcinogen; central-nervous-system effects from inhalation. (IARC, EPA) |
| Tolland CountyFIPS 09013 | — | 5 | 6k lb | -20% | Nitrate compounds (water dissociable; reportable only when in aqueous solution)Health riskDrinking-water nitrate causes methemoglobinemia ('blue-baby syndrome') in infants; EPA MCL is 10 mg/L as N. (EPA) |
| Facility | City | Top chemical | Total releases | YoY |
|---|---|---|---|---|
| King Industries INC | Norwalk | MethanolHealth riskAcutely toxic if ingested or inhaled. Metabolizes to formaldehyde and formic acid, causing blindness and metabolic acidosis. (EPA) | 430k lb | +340% |
| Waterbury Screw Machine Products CO INC | Waterbury | Copper compoundsHealth riskInhaled copper fumes cause metal-fume fever; chronic ingestion above EPA's 1.3 mg/L action level damages the liver. (EPA) | 413k lb | — |
| Pratt & WhitneyRtx CORP | East Hartford | Nitrate compounds (water dissociable; reportable only when in aqueous solution)Health riskDrinking-water nitrate causes methemoglobinemia ('blue-baby syndrome') in infants; EPA MCL is 10 mg/L as N. (EPA) | 95k lb | +15% |
| Allnex USA INC. Wallingford Ct SiteAllnex USA INC | Wallingford | n-Butyl alcoholHealth riskEye and respiratory irritant; high exposure causes hearing loss and central-nervous-system effects. (NIOSH) | 89k lb | -26% |
| American Greenfuels LLCKolmar Americas INC | New Haven | MethanolHealth riskAcutely toxic if ingested or inhaled. Metabolizes to formaldehyde and formic acid, causing blindness and metabolic acidosis. (EPA) | 74k lb | +34% |
| Unimetal Surface Finishing LLCUnimetal Surface Finishing LLC | Thomaston | Zinc compoundsHealth riskGenerally low acute toxicity. Chronic high-dose exposure disrupts copper absorption and immune function. (ATSDR) | 65k lb | -30% |
| Metal Finishing Technologies LLC | Forestville | Nitrate compounds (water dissociable; reportable only when in aqueous solution)Health riskDrinking-water nitrate causes methemoglobinemia ('blue-baby syndrome') in infants; EPA MCL is 10 mg/L as N. (EPA) | 61k lb | +143% |
| Har-Conn Chrome CO | West Hartford | Nitrate compounds (water dissociable; reportable only when in aqueous solution)Health riskDrinking-water nitrate causes methemoglobinemia ('blue-baby syndrome') in infants; EPA MCL is 10 mg/L as N. (EPA) | 47k lb | -9% |
| Ametek Specialty Metal Products DivAmetek INC | Wallingford | TrichloroethyleneHealth riskTCE. IARC Group 1 carcinogen — kidney cancer; suspected liver cancer and non-Hodgkin lymphoma. EPA MCL 5 µg/L; common DNAPL groundwater plume contaminant. (IARC, EPA, ATSDR) | 46k lb | +79% |
| Connecticut Galvanizing Corp | Glastonbury | Zinc compoundsHealth riskGenerally low acute toxicity. Chronic high-dose exposure disrupts copper absorption and immune function. (ATSDR) | 41k lb | +17% |
Water utilities to watch
Largest Water Systems With Unresolved Health-Based Violations
Sorted to surface utilities serving the most people that still have an active health-based SDWIS violation on the record. Systems in compliance with no unresolved issues fall to the bottom of the ranking.
| Water system | PWSID | Population served | Health-based · 5yr | Status |
|---|---|---|---|---|
| Aquarion-Greenwich Private | CT0570011 | 53,297 | 1 | UNRESOLVED |
| Berlin Water Control Commission Municipal | CT0070021 | 5,128 | 1 | UNRESOLVED |
| Ledyard Wpca - Ledyard Center Municipal | CT0727091 | 3,294 | 6 | UNRESOLVED |
| Fairfield Hills Municipal | CT0970021 | 2,610 | 1 | UNRESOLVED |
| Tariffville Fire District Water Dept Municipal | CT1280011 | 1,477 | 2 | UNRESOLVED |
| Scwa, Oakdale Heights Division Private | CT0860031 | 876 | 1 | UNRESOLVED |
| Sharon Water & Sewer Commission Municipal | CT1250011 | 803 | 1 | UNRESOLVED |
| Woodstock Academy South Campus Private | CT1691171 | 620 | 1 | UNRESOLVED |
| Stone Bridge Center For Health & Rehab Private | CT0971011 | 504 | 1 | UNRESOLVED |
| Sunny Valley Tax District Municipal | CT0960031 | 500 | 6 | UNRESOLVED |
Superfund / NPL sites
Federal Cleanup Sites In Connecticut
Sites on EPA's Superfund National Priorities List, plus deleted sites whose cleanup objectives EPA has finalized. Federal-facility sites (defense, DOE, etc.) are flagged separately. Each link routes to a per-site page.
| Site | City | Status | Federal facility | Primary contaminant |
|---|---|---|---|---|
| Barkhamsted-New Hartford Landfill | Barkhamsted | NPL FINAL | No | 1,2-DichloroethaneHealth riskIARC Group 2B possible carcinogen; liver and kidney toxic. EPA MCL 5 µg/L. (IARC, EPA) |
| Beacon Heights Landfill | Beacon Falls | NPL FINAL | No | 2-Butanone (Methyl Ethyl Ketone) |
| Durham Meadows | Durham | NPL FINAL | No | 1,1-DichloroethaneHealth riskSuspected carcinogen (EPA C/likely); CNS depressant. Common at solvent-contaminated sites as a degradation intermediate. (EPA, ATSDR) |
| Gallup'S Quarry | Plainfield | NPL FINAL | No | 1,1,2,2-Tetrachloroethane |
| Kellogg-Deering Well Field | Norwalk | NPL FINAL | No | 1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR) |
| Laurel Park, Inc. | Naugatuck | NPL FINAL | No | 1,2-DichloroethaneHealth riskIARC Group 2B possible carcinogen; liver and kidney toxic. EPA MCL 5 µg/L. (IARC, EPA) |
| Linemaster Switch Corp. | South Woodstock | NPL FINAL | No | 1,1,1-TrichloroethaneHealth riskMethyl chloroform. CNS depressant; ozone-depleting substance phased out under Montreal Protocol. EPA MCL 200 µg/L. (EPA, ATSDR) |
| New London Submarine Base | Conning Towers-Nautilus Park | NPL FINAL | FEDERAL | ArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR) |
| Precision Plating Corp. | Vernon | NPL FINAL | No | — |
| Raymark Industries, Inc. | Stratford Downtown | NPL FINAL | No | ArsenicHealth riskIARC Group 1 carcinogen via inhalation and ingestion. EPA MCL 10 µg/L; chronic exposure causes skin, lung, bladder cancer and cardiovascular disease. (IARC, EPA, ATSDR) |
Showing the top 10 sites by status priority. 7 additional NPL-relevant sites in Connecticut have entity pages — browse them via the host-county or host-city page rollups.
Equity context · ACS 2018-2022 · USEPA-clone EJ disparity
Statewide Population Characteristics
All Connecticut block groups: 3,605,944 residents. Statewide disparity score for pm2.5 (fine particulate) sits well below the reference (41). Why we surface this →
State-level percentiles are aggregated from block-group EJScreen data. The EJ pattern within the state will be sharper at the county level — drill down for the meaningful spatial detail.
10.1%
Low-income
36.1%
People of color
5.4%
Under age 5
17.4%
Over age 64
- PM2.5 (fine particulate)Health riskFine inhalable particles 2.5 micrometers or smaller. They travel deep into the lungs and into the bloodstream — linked to asthma, heart disease, stroke, and premature death.33below the national median
- OzoneHealth riskGround-level ozone (smog) inflames the airways. Even short exposures trigger asthma attacks and worsen chronic lung and heart disease.70above the national median
- Nitrogen dioxide (NO₂)Health riskA tailpipe and combustion gas. Concentrates near busy roads and industrial sites; raises risk of airway inflammation, asthma, and lower respiratory infections in children.39below the national median
- Diesel particulateHealth riskSoot from diesel engines (trucks, trains, ports, construction). EPA classifies it as a likely human carcinogen and a major driver of childhood asthma near freight corridors.48near the national median
- Toxic releases (RSEI)Health riskEPA's Risk-Screening Environmental Indicators score — weights TRI chemical releases by toxicity, where they go, and how many people are nearby. Higher means greater modeled cancer and chronic-health risk.82in the highest 20% nationally
- Traffic proximityHealth riskPopulation-weighted distance to high-volume roads. Living close to heavy traffic raises exposure to PM2.5, NO₂, and diesel exhaust — and the cardiovascular and asthma risks that follow.80in the highest 20% nationally
- Lead-paint risk (pre-1960 housing)Health riskShare of housing built before 1960, when lead-based paint was common. Dust from deteriorating paint is the leading cause of childhood lead poisoning, which permanently impairs cognitive development.74above the national median
- Superfund site proximityHealth riskPopulation-weighted distance to NPL Superfund sites — the most contaminated waste sites in the country. Nearby groundwater, soil, and air can carry industrial solvents, metals, and other long-lived contaminants.71above the national median
- RMP-facility proximityHealth riskDistance to facilities holding chemicals at quantities large enough to require an EPA Risk Management Plan (refineries, fertilizer plants, etc.). These pose acute exposure risk during accidental releases.52near the national median
- Hazardous-waste site proximityHealth riskDistance to RCRA hazardous-waste handlers (treatment, storage, disposal facilities). Indicates potential exposure to industrial chemicals in air, soil, and groundwater.81in the highest 20% nationally
- Underground storage tanksHealth riskDensity of underground tanks (gasoline, heating oil, industrial fluids). Leaking tanks are a leading source of benzene and other volatile organic compounds in groundwater drinking-water supplies.72above the national median
- NPDES wastewater proximityHealth riskDistance to permitted industrial wastewater dischargers. Closer proximity raises exposure to pollutants released into surface waters used for fishing, recreation, and downstream drinking-water intakes.92in the highest 10% nationally
- Drinking-water non-complianceHealth riskEPA score for public water systems with health-based Safe Drinking Water Act violations. Higher means more residents on systems that recently exceeded safe limits for contaminants like lead, arsenic, or nitrate.86in the highest 20% nationally
| Indicator | Disparity score | Reading |
|---|---|---|
| PM2.5 (fine particulate) | 41 | well below the reference |
| Ozone | 75 | below the reference |
| Nitrogen dioxide (NO₂) | 56 | below the reference |
| Diesel particulate | 57 | below the reference |
| Toxic releases (RSEI) | 75 | below the reference |
| Traffic proximity | 85 | below the reference |
| Lead-paint risk (pre-1960 housing) | 76 | below the reference |
| Superfund site proximity | 39 | well below the reference |
| RMP-facility proximity | 43 | well below the reference |
| Hazardous-waste site proximity | 87 | below the reference |
| Underground storage tanks | 61 | below the reference |
| NPDES wastewater proximity | 68 | below the reference |
| Drinking-water non-compliance | 15 | well below the reference |
Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror). EJ disparity scores via the USEPA-clone GitHub mirror after EPA deprecated the public EJScreen tool in 2025; demographics from Census ACS.
Browse
All 8 Connecticut Counties With TRI Data
Pollution trends and TRI 2024 pages for every tracked county. Alphabetical.
- Fairfield County pollution· 28 facilities
- Hartford County pollution· 57 facilities
- Litchfield County pollution· 12 facilities
- Middlesex County pollution· 11 facilities
- New Haven County pollution· 60 facilities
- New London County pollution· 8 facilities
- Tolland County pollution· 5 facilities
- Windham County pollution· 12 facilities
Sources.
- EPA Toxics Release Inventory · retrieved 2026-05-07.