RICHMOND, Va. (AP) – A bill advancing in the Virginia Legislature would exempt certain chemicals used in hydraulic fracturing from disclosure in response to a public records request.Del. Roxann Robinson’s bill would exempt information about chemicals deemed a trade secret from the Virginia Freedom of Information Act. Robinson, a Republican, introduced a similar measure last year. She says it’s necessary to protect the oil and gas industry and its closely held trade secrets.But opponents say the bill could hinder first responders in an emergency and keep landowners in the dark about pollutants that might be affecting their groundwater.Fracking involves pumping water, sand and chemicals underground to split open rock formations and allow oil and gas to flow.A House of Delegates subcommittee advanced the measure on a 4-3 vote Thursday.