Poverty, Pollution and Population

To the public, the most sensitive issue of air pollution is undoubtedly its impacts on human health.

According to WHO (2014), SO₂, NO₂ and O₃ all affect the respiratory system and lung functions. More health-damaging is particulate matter, which is of complex composition and varying sizes. The smaller the particles are the greater problem they pose: While lager particles are filtered in the nose and throat, PM₁₀ can settle as far as in the bronchi and lungs. PM_2.5 even gets into the alveoli, where gas exchange takes place. The smallest particles may penetrate through membranes and migrate into other organs - including the heart and the brain – via bloodstream and cause cardiovascular and cerebrovascular diseases and cancers. The composition of particulate matter depends on its source. Major components include sulphate, nitrates, ammonia, but also black carbon, which has a large surface area and adsorbs further fine carcinogens. This sarcastic animation demonstrate the journey of PM_2.5 in human body:

The WHO Global Burden of Disease study estimated that ambient air pollution (PM₁₀ pollution here specifically) caused 3.7 million premature deaths worldwide in 2012 (WHO,2014). Rohde and Muller (2015) calculated that in China, 1.6 million premature deaths per year alone can be attributed to PM_2.5 pollution by adopting the WHO model which computes the mortality due to impacts of pollution on five diseases: ischemic heart disease, stroke, chronic obstructive pulmonary disease, lung cancer and acute lower respiratory infection (Burnett et al., 2014). This is equivalent to 4,000 deaths per day or 17% of all death in a year (Rohde and Muller, 2015). Another study by Yang etal. (2013) identified ambient air particulate matter pollution as the 4^th leading risk factor and suggested that it caused 25,227,000 DALYs in 2010. DALY is short for disability-adjusted life year, a measure of overall disease burden as the sum of years of life lost due to disease, disability and premature death across the population (WHO, n.d.).

Air pollution also causes damage to the whole ecosystem. Though relatively well-studied, these impacts – compared to the impacts on human health – rarely enter the public discourse: Wildlife inhale health-damaging contents in the air just like humans do. SO₂ and NO_x are main precursors of acid rain; NO_x also causes eutrophication. When deposited, they change the chemistry of soil or water bodies and further stress plants and animals. As a powerful oxidant, ground-level ozone enters plants through stomata and oxidizes plant tissue, eventually causing cell death and reducing photosynthesis. Deposition of particulate matter to vegetation surface may also interfere with photosynthesis by blocking the stomata (Grantz, Garner and Johnson, 2003).

Both human health and environmental effects of air pollution bring about economic impacts. A joint research of the StateEnvironmental Protection Administration (SEPA, predecessor of the Ministry ofEnvironmental Protection) and the World Bank (2007) stated that acid rain alone cost 30 billion RMB in crop damage and 7 billion RMB in material damage each year. The same study pointed out that based on conservative estimations, the cost of air pollution – taking both premature mortality and morbidity into account – was 157.3 billion RMB in 2003, or 1.16 % of the GDP. However, when using the willingness-to-pay measures to value premature deaths, the cost was raised to 3.8 % of the GDP, for Chinese people “value improvements in health beyond productivity gains” (SEPA and World Bank, 2007, pp. xv).

Over the last three decades, China achieved rapid economic growth and lifted 680 million people out of poverty (TheEconomist, 2013) at the expense of the environment. In recent years, the growth rate has been slowing down, while a demographic crisis is looming and the cost of environmental degradation has only just begun to appear (for most people, that is). Based on the various research results presented above, it is not hard to conclude that if air pollution were tackled efficiently, a healthier, longer living and thus more productive population would in turn boost the economy.  

The Status Quo

In the previous post, I have looked at the ambient air quality standards which regulate the types of pollutants monitored and their limit values. So naturally, the next question is: how exactly is the air quality in China?

Collecting data has not been easy. Although China has now established a large monitoring system with 1521 sites in 369 cities reporting hourly via the internet, most archived data is not publicly available. The China National Environmental Monitoring Centre (CNEMC) releases a report on air quality in 74 major cities every month since January 2013 (with the report from February 2013 and December 2014 missing). Only part of the aggregated quarterly and semi-annual reports is published and annual reports are not accessible. There are also third party observations, among which the monitoring programme by the US embassy is the best known. However, it only measures the PM_2.5 concentration in 5 cities.

In this post, I will first examine the CNEMC reports and then present data from two papers for current and historical situations. The aim is to provide not an extensive review of different sources of data, but rather an overall image of the scale of air pollution in China. I will, however, continue collecting and update useful data in future posts.

In the monthly reports by CNEMC, a 74 city-average is calculated for PM_2.5, PM₁₀, NO₂ and SO₂ from the monthly average concentration of individual cities (for CO and O₃ a 74 city-average is not calculated):

Data source: China National Environmental Monitoring Centre.

As can be seen from the diagram, all four pollutants demonstrate seasonal patterns. I will get back on this when I write about the causes of air pollution in China. At this point, what we are most interested in is probably an annual average and how far it is below or above the limit. As data for February 2013 and December 2014 are missing, data from March 2013 to February 2014 are taken to calculate the annual average:

	annual average (μg/m3)	annual average limit (class 2) (μg/m3)
PM2.5	70	35
PM10	116	70
NO2	44	40
SO2	38	60

Data source: China National Environmental Monitoring Centre.

The annual average concentration of all pollutants except SO₂ exceeds the corresponding limit, among which that of two sizes of particulate matter lie far beyond.   

Due to lack of aggregated data, Rohde andMuller (2015) collect real-time (hourly) data during a four month period from April to August 2014 and apply Kriging interpolation to derive pollution maps for Eastern China (east of 95°E, which includes 97% of the population), as little monitoring is done in Western China. The following figure presents the average concentration of PM_2.5, PM₁₀ and O₃ during the study period for Eastern China (top) and the Beijing to Shanghai corridor (bottom), which contains the highest concentrations and major sources of pollution. The colour coding is not based on the Chinese, but the US EPA AQI categories:

                                                Source: Rohde & Muller (2015).  

For PM_2.5 concentration, areas containing approx. 38% of the population are classified as “unhealthy” (>55.5 μg/m³). Another 45% of the population is living in areas classified as “unhealthy for sensitive groups” (>35.5 μg/m³). PM₁₀ concentration shows similar but less severe patterns, with most of China averaging “moderate” (>150 μg/m³). Ozone concentration level is “good” for most of China, except for some Northeastern cities.

These two maps for SO₂ and NO₂ show “good” levels throughout the country:

 Source: Rohde & Muller (2015). 

As the first figure shows, the air pollution in China is most severe during winter months and modest from late summer to early fall. This study period from April to August lies somewhere in between; hence the concentration values should be similar to or slightly lower than the long-term average.

The next two diagrams illustrate annual concentration of pollutants in 31 major cities from 1995 to 2009 based on official yearbook data. The pollutants measured are particulate matter (total suspended particulates (TSP) until 2000, PM₁₀ thereafter), SO₂ and nitrogen oxides (NO_x until 1999, NO₂ thereafter). As can been seen from these graphs, the level of SO₂ concentration declined consistently from 1995 to 2009, with steep drop prior to 2000. By contrast, PM₁₀ level decreased only slightly since 2003 and NO₂ concentration remained stable during this time period.

Source: Nielson & Ho (2013).

In short, air pollution is extensive in China and affects the majority of the population. Pollution of particulate matter is most severe with average concentrations exceeding both domestic and international standards.

Demystifying the Air Quality Index (AQI)

Here is the real time (hourly) air quality information published by the Environmental Protection Bureau in my hometown Taiyuan (local time: 02:00, 25/10/2015):

Source: http://www.tyshbj.com.cn/hbj/shishi/index.asp

I have pointed the mouse to Wucheng, the nearest monitoring station to my home. This opens a drop-down list in which the concentrations of individual pollutants are shown. These are sulphur dioxide (SO₂), nitrogen dioxide (NO₂), particulate matter between 2.5 and 10 micrometers in diameter (PM₁₀), particulate matter less than 2.5 micrometers in diameter (PM_2.5), carbon monoxide (CO), and ozone (O₃). All pollutants are given in 1-hour average concentration except for ozone which is also given in maximum 8-hour average, as well as PM₁₀ and PM_2.5 which are also given in 24-hour average. In the right side panel, the air quality index (AQI) of 48 is displayed on a green background. Beneath it, there is information about the location of the site, (air quality) index category and (air quality) index level, primary pollutant, health implications as well as recommended actions. So what is the difference between “air quality index category” and “air quality index level”? Why is the column “primary pollutant” blank? And how is AQI calculated?

To answer all these questions, I checked the Ambient Air Quality Standards (GB3095-2012) and the supporting TechnicalRegulation on the Ambient Air Quality Index (on trial) (HJ 633-2012). You might have guessed from the serial numbers – both of them were released by the Ministry of Environmental Protection (MEP) in 2012 and will be fully implemented in 2016. The current Ambient Air Quality Standards (GB 3095-1996) (revised in 2000) will henceforth be abolished.

The following table presents the current nationwide standards:

Source: http://transportpolicy.net/index.php?title=China:_Air_Quality_Standards

These two tables present the future standards, which had already been adopted by 74 major cities including Taiyuan in 2012:

Source: http://transportpolicy.net/index.php?title=China:_Air_Quality_Standards

Major amendments are:

1)       The 3^rd class of limit values is removed, which has been applied specifically to           industrial areas. The new standards are consisted of two classes of limit values only, 1^st for protected areas and 2^nd for the rest: residential, mixed and industrial areas.

2)       Limit values for PM_2.5 are introduced for the first time as well as the limit value for the maximum 8-hour average concentration of ozone.

3)       Limit values for PM₁₀, NO₂, lead (Pb) and Benzopyrene (BaP) are reduced (note the change of unit !), i.e. stricter.

There are also new regulations on the validity of statistics, which are not presented in these tables.

Along with the new ambient air quality standards, AQI is introduced to replace the former air pollution index (API). To calculate the AQI, an individual score (IAQI) is first calculated for each pollutant using the following equation:

where:

IAQI_p = individual air quality index for pollutant P

C_p = concentration of pollutant P

BP_Hi = concentration breakpoint ≥ C_p

BP_Lo = concentration breakpoint ≤ C_p

IAQI_Hi = air quality index breakpoint corresponding to BP_Hi

IAQI_Lo = air quality index breakpoint corresponding to BP_Lo

The breakpoints are set as follows:

Source: Technical Regulation on the Ambient Air Quality Index (on trial) (HJ 633-2012)

For example, given the real time PM₁₀ concentration of 48 μg/m³ at Wucheng station, its IAQI is:

Then, the total AQI is calculated using the following formula:

which simply means the highest of all IAQIs. The pollutant with the highest IAQI is referred to as the primary pollutant, when its IAQI is greater than 50. In this example, the AQI is 48 and though the primary pollutant is PM₁₀, it is not stated as such, for its IAQI is slightly below 50.

AQI is then classified as follows:

Source: https://en.wikipedia.org/wiki/Air_quality_index#cite_note-sepa.gov.cn-16

I quote this simplified table from Wikipedia, because I cannot find a full translation of the original in Chinese. Note that the “air pollution level” here should be “air quality index category” if translated word-to-word, and it really is just a description for the “air quality index level”, with category “excellent” corresponding to level I, “good” corresponding to II and so on. In the original table in HJ 633-2012, there is another column of “recommended actions” corresponding to the “health implications”.

At this point, I have to emphasize that AQI is a relative and country-specific value. Different countries have different concentration breakpoints corresponding to different air quality standards, though the function used for calculation is the same. What I have presented and explained above is the AQI used by the Chinese government, and an AQI of 48 in China does not necessarily equals to an AQI of 48 elsewhere.

For instance, let’s take a look at the AQI developed by the United States Environmental Protection Agency:

Source: http://www.airnow.gov/index.cfm?action=aqibasics.aqi

At the first sight, it appears to be identical with the one showed further above, because the color coding is the same. The descriptions for the air quality conditions are, however, quite different. While I cannot claim that with the levels III to VI, the description for level II “good” used in China is pretty misleading, because it definitely sounds more positive than the description “moderate” used in the US (and i doubt this is done unintentionally).

This table shows the US standards for PM_2.5 concentration:

Source: The National Ambient Air Quality Standards for Particle Pollution - 

Revised Air Quality Standards For Particle Pollution And Updates To The Air Quality Index (AQI)

Again, using the data presented at the beginning, a PM_2.5 concentration of 25 μg/m³ is converted to an IAQI of 35.7 in China, whereas according to the US standards, the corresponding IAQI is 78. If PM_2.5 were the primary pollutant, the air quality would be described as “excellent” and as “moderate” respectively.

In summary, AQIs are not directly transferable between countries. As a matter of fact, China’s ambient air quality standards are mostly weaker than that of the US, the EU and the WHO guidelines. Besides, AQI uses a discontinuous piecewise linear function with sudden jumps between line segments (here: AQI levels). Therefore, even though it provides an intuitive way for communicating the air quality to the public, we should still rely on absolute, observed values.

An Introduction

On the first weekend since I came to London, I skyped with my parents. One of the first questions they asked me was “How is the air quality there?” As if they were asking about the weather. In fact, many Chinese people check the air quality index daily on their phone, just like you would check the weather.  

Here is a picture of our particle counter.

Credit: Zhanbin Yuan (my dad)

This is our car air purifier.

Credit: Zhanbin Yuan

And this is our air purifier at home.

Credit: Zhanbin Yuan

My dad is now considering getting a ducking kit and combining it with the air purifier, so that they can serve as a ventilation and filtration system as a whole.

I was born and raised in Taiyuan, one of the major centres for energy production and heavy industry in North China. What I am trying to do here is to display an epitome of millions of Chinese people who are concerned with the air they are breathing. And they have every right to. Just take a glance at the real time air quality index map: half of China is covered by labels of orange, red, purple and even brown, which indicates an air quality index from 101 to over 300 (the colour codes and indices are explained lower down the page). And although it has only become a major issue since 2012/2013, air pollution has been around since the start-off of the economic growth in the late 1970s. The outlook remains grave, given the ever-increasing demand for energy on the one hand and the heavy reliance on coal on the other.

As the assignment of the Global Environmental Change module that I am taking at UCL, we are asked to set up our own blogs and write about one environmental issue in the course of this term. I have chosen air pollution in China as the theme, because it is something that I am not only interested in but I can also personally relate to. So despite the intimidating facts that this my first blogging experience, I will be blogging in a foreign language and it will be viewed and assessed, there is actually quite a lot of excitement as well. In the upcoming months, I intend to cover (but not limit myself to) the following aspects of the theme: the status quo of air pollution in China, its local and regional to global impacts, the causes, current policy and measures taken, lessons from developed countries in the past and lessons for the future, air pollution and global warming as well as China on COP 21. By the end of the term, I hope that air pollution is no longer merely an area of concern, but an area that I actually know something about.

All in all, welcome and please feel free to comment and argue, as I believe every feedback is constructive. And finally, check out this short film “Smog Journeys” made by Jia Zhangke, one of the most celebrated directors in China and my personal favourite, for Greenpeace. I hope this seven-minute, dialogue-free piece arouses your attention, as it aroused my emotions about the subject matter.