Tag Archives: Nanjing

Nanjing Publishes Real Pollution Data on Weibo, Then Deletes It

Beijing residents are probably familiar with the Twitter account @BeijingAir, which is run by the US Embassy and runs real-time updates on the air quality in Beijing. The reason this is necessary is that Beijing — and indeed China as a whole — does not publish data about PM2.5 particles in the air.

PM — which stands for Particulate Matter — is a way of measuring the amount of particles in the air. The number after PM indicates the size of the particles in micrometers. From the EPA’s official site:

Particles less than 10 micrometers in diameter (PM10) pose a health concern because they can be inhaled into and accumulate in the respiratory system. Particles less than 2.5 micrometers in diameter (PM2.5) are referred to as “fine” particles and are believed to pose the greatest health risks. Because of their small size (approximately 1/30th the average width of a human hair), fine particles can lodge deeply into the lungs.

The Chinese government doesn’t publish PM2.5 numbers because they are pretty horrific, as Beijing residents who recall the #crazybad incident (or this year’s “beyond index” postings) are well aware. In fact, the US Embassy’s real-time posting of PM2.5 data so irked the Chinese government that they requested the Embassy find some way to ensure only Americans could see the tweets, according to Wikileaks cables. (The Embassy declined, and soon after Twitter was blocked in China and it became something of a moot point).

Anyway, earlier this week, a Chinese city did publish PM2.5 data publicly on it’s official Sina Weibo account. It just wasn’t on purpose. (Thanks to @kinablog for finding this link). The following is a partial translation of this article from Southern Metropolis Daily. I’ve left out bits that are non-essential or redundant given the explanation above.


At 7 AM on 11/14, the official Nanjing Weather microblog account posted a weather forecast as it always does, but this time for the first time ever they included PM2.5 [pollution] data from the day before. This is the first time PM2.5 data has ever been published by a city on the mainland. Shortly after, the microblog post was reposted by the Nanjing City Propaganda Committee official microblog account, but right after that the post was deleted, and the person who made the “Nanjing Weather” account post was sought for investigation. A representative for the Nanjing Meteorological Office [which runs the Nanjing Weather microblog] said that the Nanjing Meteorological Department does not have the right to publish PM2.5 data, and should not be tweeting it on microblogs.

That day, the Nanjing Weather tweet with the weather forecast said this:

In recent days, the atmosphere has been stable, but although the weather is clear, the air has been murky. A city probe found that visibility was under 8km and that PM2.5 levels were above 75ug/m^3, which is higher than usual.

When reposting this message, the Nanjing Propaganda Committee’s microblog account specifically added the warning “Please pay attention and protect yourself [i.e. protect your health].”


In accordance with the measuring standards of the US Embassy in Beijing [which uses the EPA standards used in the US], Nanjing’s 75ug/m^3 reading for PM2.5 corresponds to 156 on the Air Pollution Index, which is classified as Unhealthy. This level of pollution carries the warning: “individuals with breathing or heart problems should reduce outdoor exercise.” [Although it’s worth noting that in Hong Kong, the same exact level of pollution is classified as “Very High” and the warning notes that healthy people may also experience discomfort].

After Nanjing Weather posted the PM2.5 data, it was rapidly reposted and noticed by netizens […] but the post in question was soon deleted from the Nanjing Weather and Nanjing Announcements accounts.

A spokesperson for the Nanjing Meteorological Department said that they do not have the right to post PM2.5 numbers publicly, according to a Nanjing Longhu Net report. The spokesman said that the microblog post should have have been sent out, and that they quickly handled the situation by deleting the post and finding the person responsible. The spokesman also confirmed that the Nanjing Meteorological Department does have two instruments that monitor PM2.5 levels, but that data is not public, and is only used for research. The spokesman said that as far as publishing PM2.5 levels goes, “that would be a good thing for most of the common people but from the Meteorological Department’s perspective it’s an instance of breaking a regulation, and that now is not the right time to publish these numbers. In the future, we will work together with the environmental protection bureau to publish them.”

The vice-department head of Beijing’s Environmental Protection Department was asked in an interview on ChinaNews on November 11 whether China had plans to begin publishing PM2.5 data, and he responded that Beijing would take the lead on this front, saying “Beijing is the capital, so perhaps it will move a bit faster [than other cities].”


This matters because, unpleasant smell aside, PM pollution is no joke. Check it:

The results of the 2002 follow-up study showed significant associations between PM2.5 and elevated risks for cardiopulmonary and lung cancer mortality. The study found that each 10-microgram per-cubic-meter increase in long-term average PM2.5 concentrations was associated with approximately a 4% increased risk of death from all natural causes, a 6% increased risk of death from cardiopulmonary disease, and an 8% increased risk of death from lung cancer. Associations were also found with sulfur-containing air pollution but not other gaseous pollutants. On the other hand, measures of coarse particles were not consistently associated with mortality.

As the study researchers indicated in the press release for this study, the lung cancer risk associated with exposure to fine particulate matter is comparable to that faced by nonsmokers who live with smokers, and are exposed long term to secondhand cigarette smoke.

So, if each 10 ug/m^3 results in a 6% increased risk for cardiopulmonary disease and an 8% increased risk for cancer, then Nanjing’s 75 ug/m^3 air means that (assuming the air remained around that level most of the time) long term exposure would give Nanjing denizens a 45% increased risk of dying from cardiopulmonary disease and a 60% increased risk of dying from lung cancer, compared to a person who’s breathing clean air.

I don’t even want to think about what those numbers might look like for Beijing.

In the midst of China’s political problems, it’s good to remember that although the oppression is cruel and frustrating, pollution is an equally dire threat that affects literally everyone with functional lungs.

Well, everyone except government officials, who get access to special purified air along with their special organic food.