EMF, Schools & Your Family

California's Department of Education recommends a 350-foot setback between a school and the edge of a 500 kV transmission easement (the buffer grows with voltage). Community mapping of SDG&E's projected alignment shows portions of Vail Ranch Middle School falling inside that 350-foot zone. ^[1]

The state takes these fields seriously in its own process, too. The CPUC — the very agency that will decide this project — requires utilities to reduce magnetic-field exposure through no-cost and low-cost design measures and to file an EMF management plan with their application. SDG&E's routing and design should be held to that standard. ^[2]

Expect SDG&E to say the line is “well under safety limits.” It is — but those limits were written to prevent immediate effects like nerve stimulation, not the childhood-leukemia association that prompted the health classification. Being under that limit does not address the concern. ^[3]

The World Health Organization's cancer agency classifies the extremely-low-frequency magnetic fields from power lines as “possibly carcinogenic to humans” (Group 2B). That label rests on a consistent finding: roughly a doubling of childhood-leukemia risk at the highest residential exposures — above about 0.3 to 0.4 microtesla. ^{[4] [5]}

We state this honestly. The WHO also concludes the evidence is “not strong enough to be considered causal” — there is no proven mechanism, and the association has not strengthened in newer studies. That is a reason for precaution, not panic, and we will not claim this line “causes cancer.” ^[5]

What is not in dispute is that the field falls off steeply with distance — from its strongest directly beneath a 500 kV line down to that ~0.3 microtesla range by roughly 300 feet, and to ordinary household background beyond about 400 feet. ^[6] Distance is the one proven way to lower exposure. The prudent course is simple: keep a new 500 kV line away from homes, schools, and the places children spend their days. ^[6]

These studies didn't measure a brief jolt — they measured the average magnetic field inside homes, around the clock, over months and years. That makes the question simple: which homes sit closest to the line, day in and day out? Residents don't choose the exposure, it runs 24/7 for decades, and children — the group the research is about — are home the most. ^{[4] [5]}

Because the field is strongest at the wires and drops off fast, only the homes nearest the right-of-way would sit in the 0.3–0.4 microtesla range the studies flagged. In one California survey of homes near transmission lines, about one in ten of the closest homes reached that level, while homes set farther back fell to ordinary background. ^[7]

We'll be straight about the limit of this: below that range the studies do not show a clear effect, and there is no recognized “no safe level” for these fields. That is exactly why routing decides everything — push a 500 kV line up against neighborhoods and you put the closest homes in the band of concern; keep real distance and you don't. ^{[8] [7]}