Deny the variance. Earlier commenter Jesse Beck covered everything:
1.Many data centers are now being built very close to houses. Generators are not good for the air which will be blowing through these neighborhoods (especially in Prince William County). Bad air can cause breathing problems, especially for younger children.
2.The data centers using generators next to neighborhoods will also be very noisy and affect the quality of life and sleep, also not good for family and young children.
3.Once this variance is given, the folks that live next to these sites will have to live with the consequences as variance often times will need extended. A precedent will be set as more will be soon to follow, and families that bought houses (originally not zoned for data centers) near these sites, health will be at risk.
4.Best practice for sustainable growth and the health of a community, would be infrastructure to support building be built and completed BEFORE any required user is building/permitted to build. You would not build houses with no road/septic/water/electric load carrying capability... Virginia would be asking for problems continuing in this manner (maybe even legal exposure).
Builders/Data Center Companies unfortunately have unlimited resources to lobby decision makers, and have all the power to build and change the peaceful communities that were once where houses were supposed to go (zoned as such)... in some cases placing datacenters completely surrounded by communities.
I personally think Virginia is one of the greatest states in the nation and have lived here 45 years. Our state should at a minimum take the consideration of health of Virginians first, before Data Centers. Otherwise, unintended consequences and damage will be done to the children/families that live near these locations.