In his offices in central Beijing on a recent afternoon, Ma Jun, the director of the Institute of Public and Environmental Affairs, a nongovernmental organization, moved his mouse over a computer screen showing a map of real-time air emissions from more than 4,600 Chinese factories. The red rectangles, one for each factory, overlapped one another like badly laid mosaic tiles.

In all, 270 factories across China were shown to be exceeding emissions on the map on the institute’s website, probably a fraction of the total number of polluting factories in China. But data itself is an improvement, he said.

Logging emissions is an important step in securing the transparency that China needs to solve its pollution problems, Mr. Ma argues. Among the harmful pollutants are air particles known as PM2.5, which can enter deep into the lungs and even into the bloodstream. In an interview, he talked about the considerable progress he sees in the Chinese government’s approach to air pollution, but also how concerns about social unrest continued to constrain discussion of pollution’s damage to public health.

Where do things stand today?

Before 2013, levels of PM2.5 [the finest and deadliest particulate matter] were not monitored or made public in a single city. Now it’s monitored and released in more than 400 cities. China has entered an era when air quality information is released. It’s much more transparent.