Project Agent Orange — The Agent Orange | projectagentorange.com
Operation Ranch Hand opened in January 1962 and closed in 1971; across those years it put roughly 19 million gallons of herbicides over about 5 million acres of South Vietnam.
The first Ranch Hand missions flew in January 1962 — the reason the VA's presumption window opens retroactively on 9 January 1962. Early operations were limited in scale and area compared with what followed.
Mission tempo built through the mid-1960s, and the years 1967–1969 are commonly identified as the peak spraying period of the campaign. Precise per-year gallon figures vary between published reconstructions, so this page reports campaign-level totals rather than invented annual splits.
Across the whole campaign, roughly 19 million gallons (about 72,000 m³) of herbicides were sprayed. Agent Orange — a 50/50 mixture by weight of 2,4-D and 2,4,5-T, named for the orange stripe on its 55-gallon (208 L) drums — accounted for about 12 million gallons (about 45,000 m³) of that total.
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Spraying covered about 5 million acres, roughly 2 million hectares — on the order of 10% of South Vietnam's land area.
Ranch Hand ended in 1971, but the exposure question did not: TCDD dioxin, a contaminant of 2,4,5-T production, has an estimated soil half-life of 9 to 15 years under tropical field conditions. That persistence is why the VA presumption window extends to 7 May 1975.
For what that exposure is associated with, see Agent Orange Health Effects (/health-effects); for the claim rules built on these dates, see Agent Orange Presumptive Conditions and Claims (/presumptive-conditions).
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