A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected. (Photos: Xinhua)

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

Police officers patrol on a platform at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

Police officers patrol on a platform at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

Police officers stand guard at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.

A worker disinfects a train at a subway station in the Brooklyn borough of New York City, the United States, May 6, 2020. Starting on May 6, New York City subways, which usually operate 24/7, were shut down every night from 1 a.m. to 5 a.m. to allow trains to be disinfected.