Sen. Ed Markey (D-Mass.) has written Comcast Chairman Brian Roberts asking for assurances that viewers in the Boston DMA will continue to have "reliable" access to NBC content free, over-the-air after it ends its affiliation with WHDH there starting in January.

Markey cited reports that NBC would use a New Hampshire transmitter and perhaps a low-power TV in Boston to deliver the over-the-air signal.

Markey said he was concerned that when NBC launches its station in January some Massachusetts communities and others will no longer have that reliable access.

He says seniors, low-income residents and cord-cutters could be "particularly impacted" by the move if there is a reduction in coverage.

"As a longtime supporter of fee, over-the-air local broadcasting," Markey said, "I strongly encourage you to ensure that all residents in the Boston DMA enjoy the same quality and reliability of free, over-the-are NBC content.

Markey asked Roberts for info by Dec.12 on 1)  what transmitter NBC will be using; 2) whether it will be ready by January, 3) how many Boston DMA households will receive "reliable indoor and outdoor antenna coverage," 4) what communities, if any, will not enjoy that same access, and 5) how is NBC letting viewers know of the change.

“WBTS (8.1) and WNEU (60.2) are currently operating and airing the Countdown NBC station," said Comcast in a statement. "We will be providing additional detail in our response to Senator Markey’s letter.”