During winter 2017-2018, China implemented an ambitious action plan to tackle winter smog episodes. This presentation looks at the impacts of that action plan on air quality inside and outside the target region, breaks down the impact of policy and favorable weather conditions, and looks at what might be next for China's battle against air pollution.

1. Is China winning the battle on air
pollution?
Tracking the effects of the autumn-
winter air action plan

2. Big picture – huge improvement in
Beijing region in five years
Winter 2012-13

3. Winter 2017-18
Big picture – huge improvement in
Beijing region in five years

4. Even as average levels fell, winter pollution
peaks seemed to be getting worse
Source: Greenpeace analysis of Ministry of Environmental Protection hourly air quality data

5. Response: Winter action plan
• Output restrictions on iron & steel and aluminum, closure of
cement and coking plants
– Up to 25% of steelmaking and 10% of cement capacity affected
• New focus area: 2+26 cities
• New environmental protection bureau for Jing-jin-ji
• Massively ramped-up central government enforcement: tens
of thousands of inspections
• Replace coal heating&cooking in 5.5 million households
• Ban on construction and restrictions on heavy trucks
• Target: 15% reduction in October-March average PM2.5, year-
on-year

6. Winter action plan created a new focus area (“2+26”),
including most of the emission hotspots in Beijing region
2+26 cities

7. Results: dramatic reduction in pollution levels,
far exceeding targets

8. YRD=Yangtze Delta
PRD=Pearl River Delta
Jingjinji=Beijing-Tianjin-Hebei

9. Comparing 2017-18 winter with
previous one
• In 28 cities: Major reduction in PM2.5, SO2 and CO
levels, less impressive in NO2 levels
• Increase in PM2.5 levels in Yangtze Delta, Jiangsu and
much of the south.
• Rest of the country saw negative progress on NO2. Part
of this is related to relocation of industrial production
and power demand away from 28 cities.
• Lack of progress on NO2 is problematic for both PM2.5
(after falls in SO2 emissions NOx is now the main
precursor to PM2.5 formation) and ozone (which has
been getting worse)

10. What was the role of policy vs.
natural variation?

11. month
Beijing monthly mean wind speeds (m/s)
• Beijing wind
conditions were
much more
favorable than year
before, especially in
Nov-Jan.
• Simply comparing
average pollution
levels for this winter
and past winter will
give little useful
information about
the effectiveness of
the action plan. year

12. Wind speeds have a strong effect
on average PM2.5 levels. Many
other weather variables have an
even stronger and more
complicated impact.

14. • While it’s clear that weather is the dominant factor in the variation of pollution levels on daily and
monthly basis, the relationship between weather variables and PM2.5 levels is complex and non-
linear.
• Gradient boosting algorithms are generally the tool of choice for these kinds of problems.
Comparison with linear and generalized additive models confirms the benefits of using the more
complex model.

15. R2: 91.3%

16. R2 for hourly values
-training data: 72.1%
-testing data: 69.5%
• We can predict expected concentrations using hour-to-hour weather data and past PM2.5
measurements, by using simple machine learning (Gradient Boosting Model)
• Beijing made significant progress since start of 2017. Winter action plan brought about by far
the largest deviation from predicted PM2.5 levels (policy effect) on record in Beijing. The
effect was largest in November-December and started to fade in February.
• Looking at the predicted (red) line, it’s also clear that conditions during winter 2017-2018 are
much more favorable than during past two winters (but similar to 2014-2015 winter!)

17. • In the entire 28 cities region, there was progress
through 2017, and a very clear policy effect October-
January, with much less effect in February-March

18. • There were very dramatic reductions in SO2 and CO levels, not explained by weather, across the region. SO2 has a short atmospheric
lifetime so it reflects emissions near the urban areas with monitoring stations, resulting from reductions in residential coal use and
improved stack emissions enforcement.
• Beijing, Tianjin and Shanxi also saw pronounced reductions in NO2 levels, reflecting lower emissions from industry and possibly
transport
• For PM2.5, the ‘policy effect’ was by far largest in Tianjin and Beijing, with 25% gap between predicted and measured concentrations
• All pollutants in all provinces fell more than predicted based on weather

19. Winter action plan blunted
pollution peaks
• Measured pollution
levels fell the most
during days when
predicted PM2.5 level
was >200ug/m3

20. • We can further verify the impact of the action
plan by comparing progress inside and outside
the action plan target area (28 cities)

21. • SO2 and CO levels also fell strongly outside the winter action plan area, likely due to reductions in residential
coal use, especially in Shanxi where areas outside the 2+26 cities also implemented coal bans, and improved
stack emissions enforcement.
• With the expection of north Hebei, NO2 levels did not fall from predicted values. Especially Anhui saw a
large increase, likely due to substantial growth in coal-fired power and industrial output.
• PM2.5 concentrations fell, albeit much less than in the action plan region, with the exception of Jiangsu
which saw an increase compared to predicted values.

22. February-March trends
• Reversal of favorable weather conditions and
industry output restrictions saw rebound in
PM2.5 levels
• Inner Mongolia and northwest affected by
sandstorms

24. Industry came roaring back as
production restrictions ended

25. • The provinces with
worsened air quality saw
major increases in energy
intensive industry output,
including steel, non-ferrous
metals and coal-fired
power.
Source: National Statistical Bureau, via Wind Information
2017Q4 industrial output, YoY

26. January-February industrial output
• Thermal power generation +10%
• Crude steel output +6%
• Cement output +4%
• Led by provinces outside the Beijing region,
but both Shanxi and Hebei steel output
increased despite restrictions
• Extent of rebound after industry restrictions
ended on March 15 will be visible in March
output data (published Apr 17)

27. What next?
“Three-year plan to win the battle for blue skies”

28. What next?
• New 3-year national action plan expected:
strong rhetoric about ‘bringing back blue
skies’
• What’s the ambition level?
• Focus on Beijing vs. key regions vs. national
level?
• Will new ministry centralize enforcement?
• More gradual/systematic policymaking (“精细
化”) vs. campaign-style policies?

29. Structural reform will become even more
important as low-hanging fruit is picked
• Environmental ministry experts emphasize
importance of solving ‘three structural problems’:
– energy structure (excessive reliance on coal & oil)
– economic structure (excessive reliance on smokestack
industry & fixed asset investment)
– transportation structure (excessive reliance on private cars
& trucks)