The Centers for Disease Control and Prevention reissued guidelines Thursday for people concerned they may contract anthrax from contaminated mail, though the agency stressed the risk is “very low.”

The mail-handling advice came as the CDC disclosed that 85 million pieces of mail went through New Jersey and Washington postal facilities that handled anthrax-filled letters before the centers were closed.

“Would an old envelope that might have been contaminated or cross-contaminated have a spore or two on it? Could it still? Yes,” CDC director Dr. Jeffrey Koplan said. “But there really isn’t a basis for undue alarm and fear around this.”

Infection from cross-contamination is unlikely, Koplan said, because lingering spores that have survived this long on envelopes are probably larger, less dangerous ones. Still, he said, some people may want to handle mail carefully.

In Wallingford, Conn., an environmental cleanup crew Thursday was sanitizing mail sorting equipment that tested positive for trace amounts of anthrax, postal service spokesman Jim Cari said.

The work came after 94-year-old Ottilie Lundgren of Oxford, Conn., died from inhalation anthrax last month. The Wallingford postal facility distributes mail to three counties, including the one where Oxford is located.

The Connecticut Department of Public Health reported no new anthrax cases and no new test results Thursday.

The CDC suggested that people concerned about exposure keep mail away from their faces when they open it, avoid blowing or sniffing the contents, avoid tearing or shredding the mail before throwing it away, and frequently wash their hands.

Simply not opening mail that appears suspicious is also an option, as is throwing away the envelopes, the CDC said.

“If there are some spores on the outside of an envelope, the more vigorously you shake it or bang it up, they’re more likely to come off,” Koplan said. “It’s probably better not to slap it around, wave it in the air or tear it too aggressively.”

–Associated Press