| --- |
| license: cc-by-4.0 |
| pretty_name: "dcair: reported air emissions from US data centers" |
| language: |
| - en |
| size_categories: |
| - 10K<n<100K |
| tags: |
| - air-quality |
| - data-centers |
| - emissions-inventory |
| - backup-generators |
| - diesel |
| - environmental-health |
| - epa |
| - nei |
| configs: |
| - config_name: best |
| default: true |
| data_files: data/best.csv |
| - config_name: long |
| data_files: data/long.csv |
| - config_name: coverage |
| data_files: data/coverage.csv |
| --- |
| |
| # dcair: reported air emissions from US data centers |
|
|
| Facility-level air emissions that US data centers report to state and local air agencies, compiled from |
| every public source we could find, with EPA's National Emissions Inventory (NEI) filling the gaps. |
| Nearly all of it comes from on-site backup generators (mostly diesel, some gas turbines). Version 1, November 2026. |
|
|
| Data: [huggingface.co/datasets/zer0contextlost/dcair](https://huggingface.co/datasets/zer0contextlost/dcair) · Code and notes: this repo. |
|
|
| ## Why this exists |
|
|
| No federal program tracks data-center air pollution as a category. Data centers don't report to TRI, |
| grid electricity isn't counted under GHGRP, and NEI only includes the sites each state chooses to submit. |
| In Virginia, the state with the most data centers, **only 28 of 183 DEQ-permitted data centers appear in any |
| NEI year from 2012 to 2023**. Twenty-five of them show up at once in 2022, including one permitted since |
| 2003, because Virginia started sending them, not because they were built then. Building a trend from |
| NEI mostly measures reporting changes. |
|
|
| Several state and county agencies do publish facility-level actual emissions that include smaller |
| (minor and synthetic-minor) sources. This dataset puts those together. |
|
|
| ## What the numbers are |
|
|
| - What the facility or agency **reported**: annual estimates from fuel use or run hours times emission |
| factors. Not measurements, and not our estimates. |
| - Each state is **its own series**. Sources differ in which sites must report, which pollutants are |
| included and how the reporting year is defined. Don't add states into a national total or compare |
| them as if they were measured the same way. |
| - Coverage grows over time in most sources, so rising totals partly reflect more sites entering the |
| data. Facility counts are shown next to every total. |
| - This covers on-site emissions only. Emissions from the power plants supplying data centers are a |
| separate (and larger) question; see Hernandez-Cortes, Meng & Weber (2026) and Muller (2026). |
|
|
| ## Latest year per source |
|
|
| <!-- from SUMMARY.md; NOx/PM2.5/formaldehyde in short tons per year, QA-flagged values excluded --> |
|
|
| | state | source | year | facilities | NOx t | PM2.5 t | |
| |---|---|---|---|---|---| |
| | VA | Virginia DEQ air sites emissions | 2024 | 148 | 796.2 | 38.4 | |
| | AZ | Maricopa County AQD annual emissions inventory | 2025 | 12 | 213.9 | 4.3 | |
| | CO | EPA NEI | 2023 | 15 | 136.0 | 10.6 | |
| | OR | EPA NEI | 2023 | 14 | 129.9 | 8.6 | |
| | TX | TCEQ point source emissions inventory | 2024 | 7 | 110.9 | 2.0 | |
| | IL | EPA NEI | 2023 | 13 | 83.9 | 3.3 | |
| | CA | CARB facility criteria emissions | 2024 | 26 | 40.9 | n/a | |
| | UT | EPA NEI | 2023 | 4 | 32.1 | 4.4 | |
| | PA | PA DEP site-level emission inventory | 2025 | 5 | 11.7 | 0.2 | |
|
|
| Multi-year state series (NOx tons, facilities in parentheses): |
| - **Maricopa County, AZ:** 2016 15 t (7), 2019 74 t (6), 2021 95 t (10), 2023 185 t (15), 2025 214 t (12) |
| - **Texas:** 2021 45 t (3), 2022 15 t (5), 2023 28 t (5), 2024 111 t (7) |
| - **California:** 2016 4 t (6), 2020 12 t (12), 2024 41 t (26) |
|
|
| Largest single facility-years: Amazon IAD-132/133, VA (77.6 t NOx, 2023 NEI); Iron Mountain, Manassas VA |
| (74.0 t, 2024); Microsoft, Bexar County TX (66.8 t, 2024); CyrusOne Chandler, AZ (63.9 t, 2023); |
| Microsoft Broadway Rd, AZ (59.4 t, 2025). Full tables in [SUMMARY.md](SUMMARY.md). |
|
|
| ## Sources |
|
|
| | State | Source | Years | Covers | Pollutants | Gaps | |
| |---|---|---|---|---|---| |
| | VA | DEQ "Air Sites" + "Air Sites Emissions TPY" (ArcGIS EDMA layers 294/292) | 2024 | 148 of 199 sites DEQ flags as data centers, incl. minor sources | NOx CO VOC SO2 PM PM10 PM2.5, some HAPs | DEQ publishes only the current year; earlier years need a records request | |
| | CA | CARB facility emissions (CEIDARS), SIC 7374, statewide | 2000-2024 | permitted facilities reported by air districts | NOx CO ROG (as VOC) SOx PM PM10 | no PM2.5; SIC 7374 includes offices, so only name-confirmed sites are headline | |
| | TX | TCEQ point source emissions inventory, site summaries | 2010-2024 | sites over 30 TAC 101.10 thresholds | NOx CO VOC SO2 PM PM10 PM2.5 Pb | most data centers fall under thresholds; generators under PBR 106.511 need no registration | |
| | PA | DEP 25-year site-level emission inventory (Power BI), NAICS 518210 | 2017-2025 in our export | DEP-notified sources incl. synthetic minors (since 2020) | criteria, GHGs, a few HAPs | one manual export (2026-11-04), not yet scripted; non-518210 data centers missing | |
| | AZ | Maricopa County AQD annual emissions inventory (AQ Data Viewer) | 2001-2025 (one site before 2015) | non-Title V permittees, inventory requested yearly | criteria + HAP list, per engine | scraped (no bulk export); Google/Apple/Meta not found under their own names; viewer "total" tons include CO2 | |
| | OR | DEQ Air Toxics Emissions Inventory | 2016, 2020 | Title V + Simple/Standard ACDP | HAPs + diesel PM | criteria pollutants come from NEI; per-site annual reports with generator hours (2013-2023) are scanned PDFs, not yet parsed | |
| | all | EPA NEI facility summaries | 2012-2023 | whatever each state submitted | criteria + HAPs | misses most data centers | |
|
|
| In `best.csv` a state source replaces NEI for the same state, year and pollutant group (CA always uses CARB). |
|
|
| Not public, needs records requests: Virginia before 2024, Washington Ecology (annual reports incl. every |
| engine start), Illinois EPA annual emission reports, Clark County and NDEP (NV), Georgia minor sources. |
| Details per state in [NOTES.md](NOTES.md). |
|
|
| ## Files |
|
|
| | file | rows | what | |
| |---|---|---| |
| | `data/best.csv` | 21,627 | headline view: confirmed data centers, one source per state-year-pollutant group | |
| | `data/long.csv` | 69,022 | every row from every source and identity tier, incl. code-only candidates and crypto mines | |
| | `data/coverage.csv` | | facilities and NOx by state, year and source | |
| | `aliases.csv` | | hand-checked identities (shell LLCs etc.) with evidence | |
|
|
| Columns: `state, source, source_url, year, facility_id, facility_name, owner, operator, tier, county, city, |
| lat, lon, naics_or_sic, pollutant, pollutant_original, tons, note, qa_flag, pattern_flag` (`pattern_flag` in `best.csv`). `tons` = short tons/year. |
| Pollutants are normalized (`NOX, CO, VOC, SO2, PM25, PM10, PM, NH3, FORMALDEHYDE, BENZENE, ACETALDEHYDE, |
| ACROLEIN, 1,3-BUTADIENE, DIESEL_PM`); everything else is `OTHER:<name as reported>` or `GHG:<name>`. |
|
|
| ## Identity tiers (`tier`) |
|
|
| - `state_flag`: the agency marks the site as a data center (Virginia's `PLA_DATA_CENTER_YN`). Virginia NEI |
| rows get this tier by registration-number join; other Virginia NEI rows are not headline. |
| - `code+name`: industry code (NAICS 5182xx / SIC 7374/7376) and a data-center name or known operator. |
| - `name`: data-center name or known operator under another industry code (NAICS 541513, 531120, etc.). |
| - `curated`: listed in `aliases.csv` with evidence (e.g. Sharka LLC = Google Midlothian, Winner LLC = Meta Fort Worth). |
| - `code_only`: industry code only. In `long.csv`, not headline (many are offices). |
| - `crypto`: crypto-mining sites coded 518210. In `long.csv`, kept separate. |
|
|
| `operator` is matched from names only; most hyperscaler shell entities are not matched. |
|
|
| ## QA |
|
|
| `qa_flag` marks values of 10 t or more that are at least 20x the same facility's median for that pollutant |
| in other years (e.g. Evocative, MA: 0.4 t NOx in 2022, 90.6 t in 2023). Values are never changed. |
| Flagged rows are excluded from the summary totals. Some flags may be real step changes. |
|
|
| `pattern_flag` marks two reporting patterns. These rows are kept and counted; the flag says how much to trust |
| year-to-year change: |
| - `repeat`: the same nonzero value for a facility, pollutant and source in 3 or more years. **45 of the 112 |
| facility NOx series with 3+ years contain a repeated value; 39 of those are NEI series** (e.g. Equinix Denver |
| VDC I, 35.67 t every year 2014-2021). A flat line usually means the number was carried forward, not re-estimated. |
| - `co_equals_nox`: CO exactly equal to NOx in the same facility-year. All 9 cases are one Maricopa site (APS |
| Aligned Energy Data Center, 2016-2025), which points to one emission factor applied to both pollutants. |
|
|
| ## Reproduce |
|
|
| ``` |
| scripts/fetch_nei.sh && python3 scripts/extract.py # NEI 2012-2023, filtered |
| python3 scripts/fetch_va.py; python3 scripts/fetch_ca.py; python3 scripts/fetch_or.py; python3 scripts/fetch_tx.py |
| node scripts/az_list.js "%data cent%" ... > list.txt # Maricopa search (playwright), then az_detail.js |
| python3 scripts/build.py && python3 scripts/summarize.py |
| ``` |
| Paths are set to `/srv/airtox/nei`; edit `RAW` in the scripts. Pennsylvania's Power BI export was made by |
| hand. `scripts/va_test.py` reproduces the Virginia NEI coverage test (uses the Public Evidence Project permit CSV). |
|
|
| ## Related work |
|
|
| - Public Evidence Project (publicevidence.org): 2020 NEI facilities coded 518210 and an index of Virginia DEQ |
| data-center air permits (CC BY 4.0). We used their permit index for the Virginia NEI coverage test. |
| - Pitt, Suen & Plisko (2026), VCU ISEE, "Localized Air Pollution Impacts from Data Centers in Northern |
| Virginia": dispersion modeling from DEQ-provided actual emissions 2015-2024. |
| - Hernandez-Cortes, Meng & Weber (2026), Energy Institute at Haas WP 363: grid-electricity emissions and |
| siting of data centers; no on-site generator emissions. |
| - FracTracker Alliance national data-center map; datacenterpermits.org (PA/VA/TX permits); Sierra Club and |
| Piedmont Environmental Council Virginia permit surveys. |
|
|
| ## License and credit |
|
|
| Agency data from Virginia DEQ, CARB, TCEQ, Pennsylvania DEP, Maricopa County Air Quality Department, |
| Oregon DEQ and US EPA (public records). This compilation is CC BY 4.0; code is MIT. |
| Corrections and additions welcome via issues. |
|
|
