Part 13 of 13 in Thirteen Records. The long article, Data Centers Don’t Have an Environmental Record. They Have Thirteen of Them., rates thirteen kinds of environmental complaint against data centers. This series takes them one at a time.
I work at a local ISP in Northern Illinois and co-founded FD-IX, an internet exchange. I have no customer, vendor, or interconnection relationship with any facility or developer named here and no financial position in any of them beyond broad-market index funds. My industry grows with infrastructure investment in a general way, which is an indirect interest; the full disclosure is at the top of the complete article.
The last of the thirteen records is the one with the least to do with the building. Fiber carries no power-frequency current. Network copper carries signal at low power. The 60 Hz fields neighbors ask about come from the substation, transformers, switchgear, and conductors that serve any large load, and the same substation would serve a plant, a hospital, or a subdivision.
That makes EMF a Selective concern as applied to data centers and a Contested one as applied to power lines, and this post rates it both ways. The science is not settled in either direction: IARC’s “possibly carcinogenic” classification from 2002 rests on a childhood leukemia association, the exposure guidelines were built to prevent acute nerve stimulation and not to address that association, and Illinois has no statewide numeric limit. Calling the concern fabricated overstates the case against it as much as calling it proven overstates the case for it.
How the ratings work. Each complaint below is stated the way it usually arrives at a hearing and rated on the scale the full article uses. Systemic: documented at compliant facilities across multiple geographies. Regional: real, but only under specific geographic or operational conditions. Isolated: documented at one or few facilities due to misconduct or atypical design. Exaggerated: the concern is real but the figures are permit ceilings or worst cases, not operating norms. Selective: a legitimate concern applied only to data centers, not to comparable land uses. Misattributed: the harm is real but the source, geography, or cause is wrong. Contested: a plausible mechanism exists but causal documentation at compliant facilities does not. Fabricated: no credible evidentiary basis exists. Where I say I found no record of something, that means a search of public sources through October 2026, not paid databases or records requests.
Electromagnetic Fields
Claim: The data center will expose neighbors to dangerous EMF. Tier: Selective. The source is power infrastructure, not the data center.
Fiber carries no power-frequency current, and network copper carries signal current at low power. The 60 Hz fields come from the substations, transformers, switchgear, and high-current conductors that serve any large load: a plant, a hospital, a distribution center, or the substation serving a subdivision. [34]
Claim: Power-line EMF causes cancer. The reverse claim: EMF concerns are made up. Tier for both: Contested.
IARC classified extremely low frequency magnetic fields as possibly carcinogenic (Group 2B) in 2002, based on associations between long-term residential exposure and childhood leukemia. [35] ICNIRP’s 2010 guidelines set public reference levels at 2,000 milligauss to prevent acute nerve stimulation, not from a risk assessment of long-term low-level exposure. ICNIRP calls the leukemia evidence “too weak to form the basis for exposure guidelines” while acknowledging pooled analyses that “indicate that an excess risk may exist for average exposures exceeding 0.3 to 0.4 µT,” 3 to 4 milligauss, about three orders of magnitude below the reference level; WHO says the evidence is not strong enough to be considered causal. [34][35a] The United States has no federal limit. Six states set numeric limits for power-line fields and five apply “prudent avoidance”; Illinois was in neither group in the 2018 international comparison, which covers statewide standards, not conditions the Illinois Commerce Commission may attach to a siting order. [36] The signal exists, the standards were not built to address it, and none of it is specific to data centers. Calling it fabricated overstates the case against it as much as calling it proven overstates the case for it.
What to ask for. Ask where the power comes from and what it requires. In my experience a campus at this scale rarely connects to existing distribution. It typically needs a new substation, switchyard, transmission upgrades, and easements, and those are sited and permitted separately, often by the utility and the Illinois Commerce Commission rather than the municipality. In the applications I reviewed, the EMF question and the visual and environmental footprint of that infrastructure did not appear. Require the applicant to identify the interconnection plan and the off-site work at the time of approval, so the council is evaluating the whole project and not just the building. Where a substation or new line will sit near homes, ask whoever designs it, the applicant or the utility, for the calculated magnetic field at the nearest homes, with the load and averaging assumptions stated. Residents will have read the 3 to 4 milligauss figure from the pooled leukemia analyses. [34][35a] That figure describes average long-term exposure in a home, in studies that show an association and not a cause. It is not a safety limit, and a property-line calculation is not the same measurement, so the useful answer says how the expected household exposure compares with it and on what assumptions.
Where the series ends. Thirteen records, one building type, and no uniform verdict. Four of the thirteen hold at compliant facilities everywhere: construction disruption, lighting’s effect on wildlife, farmland conversion, and the wastewater stream from evaporative cooling. One, infrasound, has no evidentiary basis. The rest turn on grid, climate, hydrology, design, or distance, and on whether the person making the claim carried those conditions with it. What the imported cases from Virginia, Arizona, Oregon, Tennessee, and Georgia carry to Illinois is less their harm than their gaps: no cumulative generator review, no required pre-construction well test, no state or county rule requiring an acoustic baseline, where only cities such as Yorkville and Aurora have written one, and a vesting clause that can freeze out whatever the city learns next. Before the next approval vote, put three things in the record: the baselines, measured before ground is broken; the corridor-wide estimates of generator emissions and water demand; and enforceable limits on water, noise, and generator operation that the vesting clause does not freeze. The next dispute then gets settled with a measurement.
This is part 13 of 13 in Thirteen Records, a series that takes the long article Data Centers Don’t Have an Environmental Record. They Have Thirteen of Them. one topic at a time. Previous: chemical hazards. The full article also covers where the industry, the opposition, regulators, and local government each get it wrong, and collects every condition above in one checklist.
Cover photo: Ron Clausen / Wikimedia Commons, CC0
Citations
[34] International Commission on Non-Ionizing Radiation Protection, “Guidelines for Limiting Exposure to Time-Varying Electric and Magnetic Fields (1 Hz to 100 kHz),” Health Physics, Vol. 99, No. 6, pp. 818-836, 2010. This is the current ICNIRP primary guideline for extremely low frequency fields, superseding the 1998 up-to-300-GHz guideline for this frequency range. Reference levels at 50/60 Hz: 200 microtesla (2,000 milligauss) general public, 1 millitesla (10,000 milligauss) occupational. Read directly: Table 4 general public reference level 2 x 10^-4 T and Table 3 occupational 1 x 10^-3 T at 50 to 400 Hz; “It is the view of ICNIRP that the currently existing scientific evidence that prolonged exposure to low frequency magnetic fields is causally related with an increased risk of childhood leukemia is too weak to form the basis for exposure guidelines”; pooled analyses “indicate that an excess risk may exist for average exposures exceeding 0.3-0.4 µT”; the only well-established effects in volunteers are nerve stimulation and retinal phosphenes. https://www.icnirp.org/cms/upload/publications/ICNIRPLFgdl.pdf (archived: https://web.archive.org/web/20261012204141/https://www.icnirp.org/cms/upload/publications/ICNIRPLFgdl.pdf). Milligauss figures are direct conversions of ICNIRP’s 200 µT and 1 mT (1 µT = 10 mG).
[35] International Agency for Research on Cancer, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Volume 80, “Non-Ionizing Radiation, Part 1: Static and Extremely Low-Frequency (ELF) Electric and Magnetic Fields,” 2002: ELF magnetic fields classified Group 2B, possibly carcinogenic to humans, on the basis of childhood leukaemia epidemiology, as described in ICNIRP 2010 [34] and WHO Fact Sheet 322 [35a]. https://publications.iarc.who.int/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Non-ionizing-Radiation-Part-1-Static-And-Extremely-Low-frequency-ELF-Electric-And-Magnetic-Fields-2002 (archived: https://web.archive.org/web/20260924134857/https://publications.iarc.who.int/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Non-ionizing-Radiation-Part-1-Static-And-Extremely-Low-frequency-ELF-Electric-And-Magnetic-Fields-2002)
[35a] World Health Organization, “Electromagnetic fields and public health: Exposure to extremely low frequency fields,” Fact Sheet No. 322, June 2007. IARC classification based on “pooled analyses of epidemiological studies demonstrating a consistent pattern of a two-fold increase in childhood leukaemia associated with average exposure to residential power-frequency magnetic field above 0.3 to 0.4 µT” (3 to 4 milligauss); “the evidence related to childhood leukaemia is not strong enough to be considered causal.” Copy hosted by the Bonneville Power Administration: https://www.bpa.gov/-/media/Aep/lands/EMF_WHO_EMF-Fact-Sheet-2007a1.pdf (archived: https://web.archive.org/web/20261025155101/https://www.bpa.gov/-/media/Aep/lands/EMF_WHO_EMF-Fact-Sheet-2007a1.pdf)
[36] Netherlands National Institute for Public Health and the Environment (RIVM), “Comparison of international policies on electromagnetic fields (power frequency and radiofrequency fields),” 2018, p. 8: “United States: No federal legislation is in force. In some states (Colorado, Connecticut, Hawaii, Maryland, Ohio), variations on the ‘prudent avoidance’ principle have been adopted. … In other states, fixed limits for the electric or magnetic field of power lines are set, varying from 20% to 240% of the reference level in the EU recommendation (Florida, Minnesota, Montana, New Jersey, New York, Oregon).” Illinois appears in neither list. https://www.rivm.nl/sites/default/files/2018-11/Comparison%20of%20international%20policies%20on%20electromagnetic%20fields%202018.pdf (archived: https://web.archive.org/web/20261025155410/https://www.rivm.nl/sites/default/files/2018-11/Comparison%20of%20international%20policies%20on%20electromagnetic%20fields%202018.pdf)