Ozone 8-hour 4th-highest daily max
Ozone 8-hour 4th-highest daily max in Pima County reached 0.071 ppm in 2024, 1% above the EPA NAAQS of 0.07 ppm.
County · TRI 2024
Pima County, Arizona Pollution
10 top TRI facilities tracked here. PM2.5 annual mean (NAAQS 9 µg/m³ (annual)) held roughly steady year over year (+5%). PM2.5 annual mean (NAAQS 9 µg/m³ (annual)) concentrations are roughly unchanged from 2010.
FIPS 04019 · population 1,042,393
Anomaly engine
Notable Signals
Top facilities mapped
Where Chemicals Are Released In Pima County
Each red dot is one of the top TRI facilities. Size reflects 2024 total releases. County boundary outlined in blue.
Pollutant pathways
Pima County 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 are roughly unchanged from 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 are up 28% 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 are roughly unchanged from 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 43% 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) 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 concentrations are roughly unchanged from 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 15% since 2010.
Top facilities · 2024
Where The Chemical Releases Are Concentrated
| Facility | City | Top chemical | Total releases | YoY |
|---|---|---|---|---|
| Asarco LLC Mission ComplexAmericas Mining CORP | Sahuarita | Lead And Lead CompoundsHealth riskNeurotoxin. Even low childhood exposure impairs cognitive development; chronic adult exposure damages kidneys and the cardiovascular system. (EPA, ATSDR) | 2.1M lb | -6% |
| Freeport-Mcmoran Sierrita INCFreeport-Mcmoran INC | Green Valley | Lead And Lead CompoundsHealth riskNeurotoxin. Even low childhood exposure impairs cognitive development; chronic adult exposure damages kidneys and the cardiovascular system. (EPA, ATSDR) | 1.7M lb | -32% |
| Materion Ceramics INC.Materion CORP | Tucson | Beryllium And Beryllium Compounds | 37k lb | +43% |
| FluidraZodiac Pool Solutions LLC | Tucson | StyreneHealth riskIARC Group 2A probable carcinogen; central-nervous-system effects from inhalation. (IARC, EPA) | 22k lb | +1% |
| Flsmidth Krebs INC. | Tucson | EthylbenzeneHealth riskIARC Group 2B possible carcinogen; eye and respiratory irritant. (IARC) | 13k lb | — |
| U.S. Dod Usaf Davis-Monthan AfbUS Department Of Defense | Tucson | LeadHealth riskNeurotoxin. Even low childhood exposure impairs cognitive development; chronic adult exposure damages kidneys and the cardiovascular system. (EPA, ATSDR) | 9k lb | +15% |
| Silver Bell Mining LLCAmericas Mining CORP | Marana | Sulfuric acid (acid aerosols including mists, vapors, gas, fog, and other airborne forms of any particle size)Health riskAcid mists are an IARC Group 1 carcinogen via inhalation (laryngeal cancer) and corrosive on contact. (IARC) | 6k lb | +40% |
| Swan Rd. Asphalt PlantGranite Construction INC | Tucson | Polycyclic aromatic compoundsHealth riskPAH class includes IARC Group 1 carcinogens (e.g., benzo[a]pyrene); long-term exposure raises cancer risk. (IARC, EPA) | 1k lb | -23% |
| Calportland CO Rillito PlantTaiheiyo Cement USA INC | Rillito | AmmoniaHealth riskSevere respiratory and eye irritant; high concentrations cause chemical burns to lung tissue. (EPA) | 547 lb | -14% |
| Polymer Chemistry Innovations INC | Tucson | MethanolHealth riskAcutely toxic if ingested or inhaled. Metabolizes to formaldehyde and formic acid, causing blindness and metabolic acidosis. (EPA) | 250 lb | 0% |
Superfund / NPL sites
Federal Cleanup Sites In Pima 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 |
|---|---|---|---|---|
| Tucson International Airport Area | Tucson | NPL FINAL | No | 1,1-DichloroetheneHealth riskVinylidene chloride; IARC Group 3 (inadequate evidence in humans) but liver toxic in animal studies; common TCE/PCE biodegradation product. (IARC, EPA) |
Equity context · ACS 2018-2022 · USEPA-clone EJ disparity
Who Lives In Pima County
All block groups in Pima County County, AZ: 1,042,393 residents. County disparity score for pm2.5 (fine particulate) sits well below the reference (9). Why we surface this →
14.9%
Low-income
49.9%
People of color
5.6%
Under age 5
20.4%
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.5below the national median
- OzoneHealth riskGround-level ozone (smog) inflames the airways. Even short exposures trigger asthma attacks and worsen chronic lung and heart disease.81in the highest 20% nationally
- 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.69above 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.56near 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.62above the national median
- 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.63above the national median
- 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.46near 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.81in the highest 20% nationally
- 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.40below 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.43near the national median
- 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.60near 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.98in the highest 5% 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.77above the national median
| Indicator | Disparity score | Reading |
|---|---|---|
| PM2.5 (fine particulate) | 9 | well below the reference |
| Ozone | 144 | moderately above the reference |
| Nitrogen dioxide (NO₂) | 109 | near the reference |
| Diesel particulate | 91 | near the reference |
| Toxic releases (RSEI) | 76 | below the reference |
| Traffic proximity | 95 | near the reference |
| Lead-paint risk (pre-1960 housing) | 47 | well below the reference |
| Superfund site proximity | 61 | below the reference |
| RMP-facility proximity | 49 | well below the reference |
| Hazardous-waste site proximity | 65 | below the reference |
| Underground storage tanks | 74 | below the reference |
| NPDES wastewater proximity | 123 | moderately above the reference |
| Drinking-water non-compliance | 10 | well below the reference |
Source: Census ACS 2018-2022 (5-year) + USEPA-clone EJ blockgroup stats (raw indicators + EJ disparity mirror).
Health context
Co-Located Health Indicators
Modeled adult-prevalence estimates published by CDC PLACES, paired with this county's pollution and demographic context. Comparisons are ecological, not causal — pollution and disease prevalence covary at the area level, but the data does not attribute any individual's diagnosis to local exposure. How this section works →
Adult asthma (current)
10.9%
CDC PLACES · 2025 release · BRFSS 2022-2023
COPD prevalence
6.8%
CDC PLACES · 2025 release · BRFSS 2022-2023
Coronary heart disease
6.7%
CDC PLACES · 2025 release · BRFSS 2022-2023
Diabetes (diagnosed)
11.0%
CDC PLACES · 2025 release · BRFSS 2022-2023
Frequent mental distress
16.3%
CDC PLACES · 2025 release · BRFSS 2022-2023
PLACES uses BRFSS-modeled small-area estimates, not individual records. Crude prevalence shown above is the local rate as published; comparators are age-adjusted vs the Arizona mean and the US mean — both population-weighted across counties — so geographies with different age structures stay apples-to-apples. Sources: CDC PLACES · 2025 release · BRFSS 2022-2023.
Browse
All 11 Pima County Cities With TRI Data
Pollution trends and TRI 2024 pages for every tracked city in this county. Alphabetical.
- Ajo pollution· 0 facilities
- Amado pollution· 0 facilities
- Arivaca pollution· 0 facilities
- Flowing Wells pollution· 1 facility
- Green Valley pollution· 0 facilities
- Marana pollution· 3 facilities
- Oro Valley pollution· 1 facility
- Rillito pollution· 0 facilities
- Sahuarita pollution· 0 facilities
- Tucson pollution· 8 facilities
- Vail pollution· 0 facilities
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.