Ozone 8-hour 4th-highest daily max
Ozone 8-hour 4th-highest daily max in Middlesex County reached 0.074 ppm in 2024, 6% above the EPA NAAQS of 0.07 ppm.
County · TRI 2024
Middlesex County, Connecticut Pollution
10 top TRI facilities tracked here. Ozone 8-hour 4th-highest daily max (NAAQS 0.070 ppm (8-hour)) held roughly steady year over year (-1%). Ozone 8-hour 4th-highest daily max (NAAQS 0.070 ppm (8-hour)) concentrations have fallen 17% since 2010.
FIPS 09007 · population 0
Anomaly engine
Notable Signals
Top facilities mapped
Where Chemicals Are Released In Middlesex County
Each red dot is one of the top TRI facilities. Size reflects 2024 total releases. County boundary outlined in blue.
Pollutant pathways
Middlesex County Pollutant Multi-Year Trends
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 17% 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 doubled 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) volumes here are too small to anchor a multi-year trend; YoY movement is still shown above.
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 volumes here are too small to anchor a multi-year trend; YoY movement is still shown above.
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 have more than doubled since 2010.
Top facilities · 2024
Where The Chemical Releases Are Concentrated
| Facility | City | Top chemical | Total releases | YoY |
|---|---|---|---|---|
| Kleen Energy Systems LLCKleen Energy Holdings LLC | Middletown | AmmoniaHealth riskSevere respiratory and eye irritant; high concentrations cause chemical burns to lung tissue. (EPA) | 13k lb | +16% |
| Habasit America INC.Habasit AG | Middletown | TolueneHealth riskCentral-nervous-system depressant. Chronic high exposure causes hearing loss and developmental effects. (EPA, ATSDR) | 9k lb | -12% |
| Middletown Power LLCArclight Energy Partners | Middletown | AmmoniaHealth riskSevere respiratory and eye irritant; high concentrations cause chemical burns to lung tissue. (EPA) | 8k lb | -70% |
| Vwr Chemicals LLCAvantor Performance Materials INC | Chester | AcetonitrileHealth riskMetabolizes to cyanide in the body; high exposure causes nausea, weakness, and respiratory effects. (ATSDR) | 4k lb | -31% |
| Pratt & WhitneyRtx CORP | Middletown | NickelHealth riskNickel compounds are IARC Group 1 carcinogens; inhalation exposure raises lung and nasal cancer risk. (IARC) | 3k lb | +62% |
| Hobson & Motzer, INC.Aterian Investment Partners | Durham | Ethylene glycolHealth riskAcutely toxic if ingested. Metabolizes to compounds that cause kidney failure. (EPA) | 1k lb | +373% |
| Perma Treat CorpPanam Railways | Durham | CreosoteHealth riskCoal-tar creosote is an IARC Group 2A probable carcinogen; PAH-rich preservative used in railroad ties and utility poles. (IARC, EPA) | 509 lb | -23% |
| Bourdon Forge CO INC | Middletown | NickelHealth riskNickel compounds are IARC Group 1 carcinogens; inhalation exposure raises lung and nasal cancer risk. (IARC) | 32 lb | -3% |
| Smith & Wesson Precision Components Plastics LLCSmith & Wesson Brands INC | Deep River | Tetrabromobisphenol AHealth riskBrominated flame retardant; suspected endocrine disruptor; persists in the environment. (EPA) | 11 lb | -48% |
| Whelen Engineering COWhelen Engineering | Chester | LeadHealth riskNeurotoxin. Even low childhood exposure impairs cognitive development; chronic adult exposure damages kidneys and the cardiovascular system. (EPA, ATSDR) | 3 lb | — |
Superfund / NPL sites
Federal Cleanup Sites In Middlesex County
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 |
|---|---|---|---|---|
| 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) |
Equity context
County Population Characteristics
All block groups in Middlesex County County, CT.
Demographic shares, national-percentile rankings (PM2.5, ozone, NO₂, diesel particulate, lead-paint risk, NPL/RMP/TSDF/NPDES proximity, drinking-water non-compliance), and EJ disparity scores will render here once the EJScreen-clone ingest completes for this geography. Why this section matters →
Browse
All 7 Middlesex County Cities With TRI Data
Pollution trends and TRI 2024 pages for every tracked city in this county. Alphabetical.
Sources.
- EPA Toxics Release Inventory · retrieved 2026-05-07.
All sources are federal public-domain datasets under 17 USC §105. We aggregate but do not relabel; the underlying observations remain attributable to EPA.