China’s Environment: Air

Sustainable Development Practice in China

JIANG, DaheUNEP-Tongji Institute of Environment and

Sustainable DevelopmentTongji University

To understand the situation and characteristics of China’s air pollution:

• Fundamentals of air pollution;• Historical aspects of air pollution• Air pollution in China

– China is a developing country– Energy structure– Efforts and achievements– PM2.5 and “Gray Haze”– Efforts to improve the situation– Characteristics and control strategy

Fundamentals of air pollution• Gaseous and particulate pollutants:

– Gaseous: SO2, NOx (NO and NO2), CO, HCs, VOCs, O3, … … NH3, H2S, … CO2, CH4 … toxic gases

– PMs (Particulate Matter): PM2.5, PM10, TSP, … falling dust– PMs are especially complicated: sizes and compositions:

cigarette smoke, cooking oil droplets/smoke, vehicular emissions such as diesel engine, EC, OC .. …. and secondary particles: sulfuric acid drop, sulfates, nitric acid drop, nitrates, …

• Primary and secondary pollutants:– Primary pollutants are directly emitted from sources, such as

entrained dust, stack effluents (SO2, NOx, soot, CO2, …), and vehicular emissions (CO, NOx, HCs, … SO2)

– Secondary pollutants are transformed by atmospheric processes

• Regulated pollutants:– Most common, large volume flow rate, obvious health/

environmental impacts: PM10, SO2, NO2, an add PM2.5, O3, and CO.

– API (air pollution index) or AQI (air quality index)

• Natural and manmade sources:– Natural sources: lightening, sand storm, forest fire …– Fossil fuel combustion is the main manmade sources of air

pollutants– Point/line/volume sources; constant and fugitive sources;

accidental releases

Fundamentals of air pollution

Combustion is the main Source of Air Pollutants

• Fossil fuels− Coal burning: soot, SO2, NOX, … CO, C, Hg, …− Oil combustion: NOX, CO, HC, …(SO2 from heavy oil)− Natural gas: H2S, …

• Generation mechanism of SO2 and NOx

− SO2: combustion of contaminated fuel, coal, heavy oil, sulfuric ores (metallurgy)..

− NOx: thermal (high temperature), prompt (with HC elements), and N contaminant;

− VOCs: a variety of sources, paints, oil, …

Motor Vehicle and Air Pollution

Pollutants from:• Incomplete combustion: CO, HCs,

– Often work at unstable conditions (4 strokes);– Imperfect fuel-air mixing;– Quenching adjacent to engine shells, due to cooling;

• High temperature: NOX

• Fuel contaminants, especially diesel, SO2, PMs• Lubrication ~ VOCs• Entrainment of road dust• Others … Pb, Hg, …• CO2

Air pollution and meteorological conditions• Atmospheric transport/ transformation/ removal:

– Wind and “dispersion condition”– Atmospheric chemical processes– Physical processes, … … humidity - visibility problem

• Impacts:– Health impact: acute, chronic (respiratory/pneumonia,

cardiovascular, carcinogenic)– Visibility– Environmental

Fundamentals of air pollution

Escape

Initial stage Cloud processes

Mixing Advection Chemical transformation

layer Plume rise Gravitational settling

depth Turbulent diffusion Wet scanvenging

H (Rainout, washout)

HS Dry deposition

Atmospheric processes that air pollutants undertake after being released

Atmospheric transport processes

Mixing layer !

Example: Temperature Inversions can cause poor dispersion and air pollution events

• A temperature inversion is an increase in temperature with height.• More likely over cities and in drainage basins.• Lower wind speeds allow radiational cooling of upper layer.• Air is stagnant.• Can trap pollutants below.• Allows time for chemical transformations to occur (Smog)• Can cause severe health problems due to time of exposure.

Historical Aspect of Air Pollution: From Local to Global

GLOBAL AIR POLLUTION ISSUESStratosphere ozone layer

Global warming

Acid rain, from late

1960s

CROSS BOUNDARY AIR POLLUTIONAcid rain and acidic

deposition

Los Angeles smog, 40s to 60s, to present

URBAN & MULTICITY EFFECTPhotochemical smog

London smog, 1952 and earlier

LOCAL EFFECTSoot and smoke

by heavy industry

GLOBAL ENVIRONMENTCHANGES

Global climate andenvironmental changes

London Smog (1952)

• The Great Smog of '52 or Big Smoke was a severe air pollution event that affected London during December 1952. A period of cold weather, combined with an anticyclone and windless conditions, collected airborne pollutants mostly from the use of coal to form a thick layer of smog over the city. It lasted from Friday 5 to Tuesday 9 December 1952, and then dispersed quickly after a change of weather.

• Although it caused major disruption due to the effect on visibility, and even penetrated indoor areas, it was not thought to be a significant event at the time, with London having experienced many smog events in the past. However, medical reports in the following weeks estimated that 4,000 people had died prematurely and 100,000 more were made ill because of the smog's effects on the human respiratory tract. More recent research suggests that the number of fatalities was considerably greater at about 12,000.

• It is considered the worst air pollution event in the history of the United Kingdom, and the most significant in terms of its effect on environmental research, government regulation, and public awareness of the relationship between air quality and health. It led to several changes in practices and regulations, including the Clean Air Act 1956

London smog: 1873, 1880, 1881, 1882, 1891, 1892, 1901, 1942

The high death rate is correlated closely with extremely high SO2 and soot concentrations;Primary pollutants

Weather condition and pollutant sources• The weather preceding and during the smog meant that Londoners

were burning more coal than usual to keep warm. Post-war domestic coal tended to be of a relatively low-grade, sulphurous variety (economic necessity meant that better-quality "hard" coals tended to be exported), which increased the amount of sulphur dioxide in the smoke. There were also numerous coal-fired power stations in the Greater London area, including Battersea, Bankside, and Kingston upon Thames, all of which added to the pollution. Research suggests that additional pollution prevention systems fitted at Battersea may have actually worsened the air quality, reducing the output of soot at the cost of increased sulphur dioxide, though this is not certain. Additionally, there were pollution and smoke from vehicle exhaust—particularly from diesel-fuelled buses which had replaced the recently abandoned electric tram system—and from other industrial and commercial sources. Prevailing winds had also blown heavily polluted air across the English Channel from industrial areas of Continental Europe.

Los Angeles Smog 1940s and later

Los Angeles smog --- Photo chemical smog• In the 1940~1950s a new type of smog, known as photochemical

smog, was first described. This forms when sunlight hits various pollutants in the air and forms a mix of inimical chemicals that can be very dangerous. A photochemical smog is the chemical reaction of sunlight, nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the atmosphere, which leaves airborne particles (called particulate matter) and ground-level ozone.

• Nitrogen oxides are released by nitrogen and oxygen in the air reacting together under high temperature such as in the exhaust of fossil fuel-burning engines in cars, trucks, coal power plants, and industrial manufacturing factories. VOCs are released from man-made sources such as gasoline (petrol), paints, solvents, pesticides, and biogenic sources, such as pine and citrus tree emissions.

• This noxious mixture of air pollutants can include the following:– All of these chemicals are usually highly reactive and

oxidizing. Photochemical smog is therefore considered to be a problem of modern industrialization. It is present in all modern cities, but it is more common in cities with sunny, warm, dry climates and a large number of motor vehicles. Because it travels with the wind, it can affect sparsely populated areas as well.

Conditions:• Sun light• NOx, VOC (HCs)

A mixture, HNO3, PANs, Aldehydes, O3

PM2.5…

Impacts:• irritating respiratory

system • VisibilityAttributes to vehicles ?

1948

1953

1960

1962

1964

1967

1971

1980

1984

More recent …

Feel the “haze” …

Acid rain (since late 1960s)• Acid rain and/or acidic deposition was found in late 1960s, northern

Europe. Lake water was found with less living species due to water acidity; trees were found damaged; also historic heritages, monuments, …

• Acid rain is measured with rain water pH value <5.6 (in lab, pH = 7 is neutral, but in atmosphere, due to the existence of CO2 so as carbonic acid …)

• Acidic precursors mainly include SO2, NOx, sulfates and nitrates,…• There was a hot period of acid rain research: monitoring, analysis, source

attribution, modeling, control strategy and technologies, and especially international negotiations (North America, and West Europe);

• Situation of acid rain is greatly improved in north America and west Europe, … except China and East Asia!

• In addition to desulfurization strategies and technologies, the most successful is the improvement in energy structures. For example, London and UK:

Formation of Acid Rain

The Consequences of Acid Rain

Never forget these extreme accidental releases

1984 Bhopal accident

1986 Chernobyl 2011 Fukushima

Air pollution situation in China• A developing country. Due to natural conditions and

inadequate management: dusty, PM10 is the dominant pollutants in many cities.

• Coal consumption keeps about 70% in primary energy consumption. But de-sulfurisation was just emphasized and de-nitrification just quoted.

• Number of vehicles increase rapidly.

• Acid rain pollution is getting severer.

• With obvious achievements, but in the same time, the horrible “Gray Haze” and related PM2.5 concentrations.

PM10/dusty: a management problem in addition to natural conditions, see the photos taken in Shanghai

Falling dust in Shanghai

Achievements: Take Shanghai as an example

Air quality changes in Shanghai. Before 2000, the data for particulates were for TSP, and after 2001, the data are for PM10

China’s air pollution and energy structure

15 Unlivable cities in the world – LinFen City, Shanxi

Air pollution in China’s cities is often known to the world

• located in coal mining area, so as smog and abundant pollutants.

• Clothing becomes black before being dried.

• Severe health risk

--- Based on BP world energy statistics 2011Energy consumption structure

Mill

ion

tonn

es o

il eq

uiva

lent

– Air pollutants are mainly generated by combustion– Due to the unique energy consumption structure, and

the huge amount of coal burnt annually … …

More than 3 times than that by USMore than 6 times than that by India

– What are the consequences in air pollution, such as soot, SO2, NOX, and Hg …?

– And the secondary pollutants and pollution?

China energy consumption structure change:Oil consumption is increasing quickly, however, coal consumption increases even quicker …

Comparison of coal consumptions by China and US

Note the increment during the 10th “Five-Year Plan”

In 2000 to 2005, coal consumption in China increased by 65%.Also in 2000 to 2005, “gray haze” got sever in many cities.

Result of the national survey of air pollutant emissions

Compare the major emitters: SO2 mainly come from coal burning and metallurgy; NOX comes from automobile, coal burning and matellurgy

SO2 emissions NOX emissions

Southwest and Southern were the heavy acid rain areas, however recently…

2006

2007 2008

2009

2010

Acid rain is measured by rain water pH value. However, does the result that northern China is not acidic a correct description of related air pollution there?

In “Two – Control Zone” strategy, the coefficients are therefore looser for northern China. Does it have something to do with the current issue, such as the Beijing PM2.5, and Gray Haze?

Efforts and achievements• Air Pollution Control Law• Air quality standards, monitoring system, and API/AQI reporting• Close, stop, transform, combine, move away polluting factories• End-of-Pipe control• …• SO2 emission reduction as one of the environmental target, now

adding NOx emission reduction in 12th Five-Year plan• Measures to reduce PM2.5 and Gray Haze

– PM2.5 monitoring system, with O3 and CO;– Research projects;– Energy structure and industry structure improvement;– Strict vehicular emission requirements;– Temporal measures in nearby regions

Great efforts have been made, including substantial countrywide desulfurization, so that SO2 emission is dropping from 2007

The recent Beijing “Gray-haze” is a special case: it is not because the PM2.5 pollution became suddenly worsen, but the meteorological condition became suitable!

EU standards for petroleum cars

Standard EU-Ⅰ EU-Ⅱ EU-Ⅲ EU-Ⅳ

Enforcement 1992 1996 2000 2006

HC 1.1% 1.1% 0.66% 0.46%

CO 4.5% 4% 2.1% 1.5%

NOx 8% 7% 5% 3.5%

PM 0.36% 0.15% 0.1% 0.02%

City Motor vehicle emission standards

Implementation time

Beijing

Euro I 1999

Euro II 2003.1.1

Euro III 2005.12.30

Euro IV 2008.3.1

Shanghai

Euro I 1999

Euro II 2003.3.1

Euro III 2006

Euro IV 2009.11.1

China has implemented

vehicle emission standards

COD SO2 NH4-N NOx

2001-2005 Required -10% -10%

Actually reached -2% +27%2006-2010 Required -10% -10%

Actually reached -12.45% -14.29%

2011-2015 Required -8% -8% -10% -10%

(Pollutant) Emission Reduction

In “Five-Year” Plans

Although PM10 still dominant, the API curves show the improvement of China’s air quality, and that it is getting better from northwest to southeast.

However, Gray Haze and PM2.5 …

• On October 30, 2011, air monitoring data from the U.S. embassy in Beijing suggested that the density of PM2.5, fine particles with a diameter shorter than 2.5 microns, in the air was about 250 to 350 and the general air pollution index (API), an indicator of the air quality, was 425, reaching the level of "hazardous," the worst ranking on the pollution scale according to U.S. standards. However, the API released by the BMEPB on the same day was only 132 and the air was categorized as "slightly polluted."

• What was the situation?• API? • PM2.5 & PM10?• Haze? Grey Haze? Fog-Haze? Smog?

This is “Gray Haze” ~ 2013

Upper ~before gray haze; Lower ~ during gray haze

“Gray haze” in Shanghai

The haze lasted almost 3 weeks since Feb. 10, and covered a large area of east China. Some 600 million people were influenced

• Not “Beijing Cough” or “Beijing Smog”, because:– The coverage is much larger, …；– The haze does not directly irritate people’s eyes and respiratory

system, but reduces visibility so that presents unpleasant feelings, brings effects on sensitive group of people, and most importantly, blocks traffics, and causes accidents…

– People go to Beijing, might feel to cough. There might be other reasons, such as low humidity, or dusty (air pollution other than Gray haze);

– Gray haze is due to water solvable “secondary” pollutants, e.g., sulfates and nitrates, under suitable meteorological conditions: poor dispersion but high humidity.

• Gray haze is not a “Smog” as “London smog” or “Los Angeles Smog”, because“Smog = Smoke + fog”, but “smoke” refers to that directly emitted from stacks or pipes.

• “Gray Haze” is a new type of air pollution!

Many questions:

How does China’s haze appear gray?• It is due to the water soluble components in fine particles,

PM2.5 and smaller …, sulfuric acid/sulfates, nitric acid/nitrates;• When it is dry, these particles are small and can not be seen;• Under certain meteo conditions, they particles grow larger and

lead to visibility problem ~ grey

No hazeWith haze

van Donkelaar et al. (2010) Environmental Health Perspectives 118(6), 847-855

Observed from satellite, where is PM2.5 severe ?

It is easy to understand “city cluster air pollution”

phenomena

Chinese power plant carbon emission for 2007

van Donkelaar et al. (2010) Environmental Health Perspectives 118(6), 847-855

Fine particles (sulfates & nitrates …) are water soluble. When meteorological conditions are suitable (certain humidity, and stagnation) these particles grow to cause visibility problem.

SO2

NO2

NO2

VOCOil/Vehicles

Coal burning

CO…

SootPMs

Hg ...

Acid RainFine particles:

• Sulfuric acid, sulfates

• Nitric acid, nitrates

“Grey” Haze

Photochemical Smog, Haze

Fossil fuel combustion is the main source of air pollutants

Primary pollutants Secondary pollutants

“Grey Haze” is a new term in Air Pollution Meteorology, possibly a new type of air pollution due to the unique energy of China and

insufficient desulfurization!

Vehicular emissions increases quickly, contributes to:− Road dust− NO2

− Photo chemical smog, O3

− Acid rain− Grey haze

This is the 2002 situation (AR4 of IPCC)

BJ, SH, GZ 2007

Beijing2010

Guangzhou2010Shanghai2010

City Population(Million)

GDP(billion RMB)

GDP per capita(USD)

Vehicles(million)

Vehicles per 1000 citizen

Beijing 19.61 1377.79 12172 4.89 249.34

Shanghai 23.02 1687.24 11363 3.09 134.24

Guangzhou 12.70 1060.45 12944 2.10 165.34

Air quality issues in China

• PM10 is still the main pollutant, however the situation is being improved;

• Coal burning is the main type, SO2 and NOx, sulfates and nitrates, fine particles, acid rain, and “Gray haze”;

• Vehicular emission induced air pollution is getting severer, photochemical smog & O3;

• Denitrification is as important as desulfurization;

• Carbon emission reduction …

Summary and suggestions

• The characteristics of China’s air pollution:– “Coal burning” type for the whole country in view of the

unique energy consumption structure;

– “Mixed type” air pollution in urban areas especially megacities due to increasing use of vehicles;

– Primary air pollution is under control, but secondary air pollution approaches dominant, such as photochemical smog, acid rain, and grey haze.

• Policy / strategy implications– More studies on secondary pollutants;– Include O3 and PM2.5 into monitoring and AQI

reporting;– Modify the “Two-Control” strategy, such as

strengthen mass loading control of SO2 and NOX

– Cooperative control on air pollution control within city clusters

The 10 monitoring stations of Shanghai City

“DianShan Lake” is the “boundary” station at the west edge

延庆镇 京西北八达岭昌平定陵 怀柔镇密云镇 京东北密云水库昌平镇 顺义新城平谷镇 京东东高村海淀北部新区 北京植物园海淀万柳 朝阳奥体中心朝阳农展馆 石景山古城西直门北大街 东四环北路丰台云岗 丰台花园南三环西路 房山良乡大兴黄村镇 亦庄开发区通州新城 京西南琉璃河京南榆垡 京东南永乐店

传输方向

This figure was drawn before Nov. 2012, that the heating season was not started.

It was found later that (1) stronger local effects after heating season started; (2) Southwest boundary transport is also obvious; (3) easily rises over 200 g/m3 when wind got lighter and from southern; (4) vehicular emission effect is not obvious .