The Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing) programme is an international collaborative project focusing on understanding the sources, processes and health effects of air pollution in the Beijing megacity. APHH-Beijing brings together leading China and UK research groups, state-of-the-art infrastructure and air quality models to work on four research themes: (1) sources and emissions of air pollutants; (2) atmospheric processes affecting urban air pollution; (3) air pollution exposure and health impacts; and (4) interventions and solutions. Themes 1 and 2 are closely integrated and support Theme 3, while Themes 1–3 provide scientific data for Theme 4 to develop cost-effective air pollution mitigation solutions. This paper provides an introduction to (i) the rationale of the APHH-Beijing programme and (ii) the measurement and modelling activities performed as part of it. In addition, this paper introduces the meteorology and air quality conditions during two joint intensive field campaigns – a core integration activity in APHH-Beijing. The coordinated campaigns provided observations of the atmospheric chemistry and physics at two sites: (i) the Institute of Atmospheric Physics in central Beijing and (ii) Pinggu in rural Beijing during 10 November–10 December 2016 (winter) and 21 May–22 June 2017 (summer). The campaigns were complemented by numerical modelling and automatic air quality and low-cost sensor observations in the Beijing megacity. In summary, the paper provides background information on the APHH-Beijing programme and sets the scene for more focused papers addressing specific aspects, processes and effects of air pollution in Beijing.
Air pollution is one of the largest environmental risks. It is estimated
that air pollution has led to 7 million premature deaths per year globally
(WHO, 2016a, b) and over a million in China (GBD MAPS Working Group, 2016).
Air pollution also has significant impact on the healthcare system and
ecosystems, which cost about 0.3 % of global GDP (OECD, 2016). Air-pollution-related
sickness also reduces productivity, and severe haze leads
to closure of transport systems, causing additional damage to the economy.
Total economic losses related to China's PM
Considerable research effort has led to huge progress in understanding the sources and pollution processes in megacities in western countries, e.g. major interdisciplinary and multi-institutional programmes in Paris and London in the last few years (Beekmann et al., 2015; Bohnenstengel et al., 2014). Although air pollution in developed megacities sometimes breaks country-specific limits and WHO guidelines, traditional London or Los Angeles type smogs which occurred in the early and mid-20th centuries are rare. In the developing countries, however, the rush to industrialisation and rapid growth in vehicle populations have led to serious air pollution problems that are more complex than the London or Los Angeles smogs.
Air pollution is particularly severe in developing megacities, such as Beijing, where pollutants from traditional sources, such as solid fuel combustion are mixed with those from modern vehicles (Guan et al., 2014), on top of regional pollution from industrial and other anthropogenic activities. Air pollution in Beijing is different from that in well-studied developed megacities, such as Paris and London, in a number of ways including the lack of diesel emissions in the inner city, the use of coal in surrounding rural areas for heating and domestic cooking (Tao et al., 2018), the high emissions of air pollutants in neighbouring provinces (Hebei and Tianjin) and the high oxidising power due to the complex chemistry (Zhang et al., 2009; Li et al., 2017; Lu et al., 2018). This makes Beijing a particularly interesting place to study as it provides an atmospheric environment with major contrasts to developed megacities such as London and Paris in which to investigate urban pollution processes.
Many research programmes have been initiated in Beijing to study the air
pollution processes since the late 1990s. Earlier research programmes (e.g.
early 2000) focused on primary emissions of
The Beijing Olympic Games (2008) offered additional incentives to improve
air quality and this led to the funding of CAREBeijing (Campaigns of Air
Pollution Research in Megacity Beijing and Surrounding Region) and other
major programmes. The field campaigns were conducted in the summers of 2006,
2007 and 2008, with the objectives to learn the environmental conditions of
the region, to identify and quantify the processes (transport and
transformation) that led to the impact of the surrounding area on air
quality in Beijing and to formulate policy suggestions for air quality
improvement during the 2008 Beijing Olympic Games. Measures developed as a
result of this and other programmes successfully improved air quality during
the Olympic Games and provided valuable examples for developing air
pollution control policy in other cities (Wang et al., 2010). CAREBeijing
was later extended to CAREBeijing-NCP (Campaigns of Air Pollution Research
in megacity Beijing and North China Plain), in which field campaigns were
carried out in the summer of 2013 and 2014 to investigate the transport and
transformation processes of air pollutants in the Beijing megacity and North
China Plain. The results of CAREBeijing and CAREBeijing-NCP have been
published in special issues of Atmospheric Chemistry and Physics
(
The adverse health effects of air pollution provide one of the key motivations to control air pollution. Research has shown that air pollution is one of the leading causes of the disease burden in China (GBD MAPS Working Group, 2016). Especially particulate pollution, the leading cause of severe air pollution events in China, has a significant impact on human health and is associated with high mortality (Q. Zhang et al., 2017), with a considerable proportion of this related to cardiorespiratory diseases (namely stroke, ischemic heart disease and chronic obstructive pulmonary disease) (Yang et al., 2013; Lozano et al., 2013). Despite this increasing evidence base, the adverse health impact of air pollution remains a complex issue. For instance, the risk assessment of disease burden due to air pollution in China has relied largely on the studies undertaken in Europe and North America, which may be subject to error due to the difference of race, lifestyle and air pollution settings (Lim et al., 2012). The marked change in air pollution sources and composition between the heating and non-heating seasons, and the differences between urban and rural areas may all lead to different biological responses in local populations. However, to date, such comparative investigations are largely lacking. A further limitation of such work is the lack of accurate personal exposure estimates which are crucial in high-quality health studies. This may be especially true when considering household air pollution from traditional biomass and coal stoves which may not be easily captured by typical outdoor monitoring instruments (Linn et al., 2001; Brook et al., 2002). Thus, understanding the health impact of air pollution in China remains a major challenge.
To address these issues, the UK Natural Environment Research Council (NERC), in partnership with the National Science Foundation of China (NSFC), UK Medical Research Council (MRC) and UK-China Innovation Newton Fund funded a major joint research programme – Atmospheric Pollution and Human Health in a Chinese Megacity (APHH-Beijing). APHH-Beijing is an integrated research programme, incorporating the capabilities and strengths of the UK and Chinese science communities, which is taking a multidisciplinary approach to investigating the sources, processes and health effects of air pollution in the Beijing megacity. The new scientific understanding underpins the development of interventions and solutions to improve air quality and reduce health impacts.
This special issue “In-depth study of air pollution sources and processes within Beijing and its surrounding region (APHH-Beijing)” documents the research outcomes of this APHH-Beijing programme, in particular the atmospheric measurement and modelling aspects.
This introduction paper describes the motivation and background of the APHH-Beijing programme and presents some of the background air quality and meteorological observations, particularly during the two intensive field campaigns. These campaigns form one of the core research activities within APHH-Beijing integrating the different themes/projects. We do not present the key scientific results of APHH-Beijing in this introduction (not an overview) paper, as much of the research activities are still ongoing and unpublished. Key findings will be published in the special issue to which this paper provides key background information.
The overall aim of APHH-Beijing is to better understand the sources,
atmospheric transformations and health impacts of air pollutants in the
Beijing megacity and to improve the capability of forecasting air quality
and developing cost-effective mitigation measures. Specific objectives
are
to determine the emission fluxes of key air pollutants and to measure the
contributions of different sources, economic sectors and regional transport
to air pollution in Beijing; to improve understanding of the processes by which pollutants are
transformed or removed through transport, chemical reactions and photolysis,
and the rates of formation and conversion of particulate matter (PM) via
atmospheric reactions; to improve understanding on how the detailed properties of PM evolve and can
influence their physical properties and behaviour in the atmosphere and
elucidate the mechanisms whereby those properties may interact and give feedback
on urban-scale and regional meteorology; to exploit new satellite observations and regional models to place the
in situ campaigns into a wider context; to determine the exposure of Beijing inhabitants to key health-related
pollutants using personal air pollution monitors and assess the association
between air pollution exposure and key cardiopulmonary measures; to determine the contribution of specific activities, environments and
pollution sources to the personal exposure of the Beijing population to air
pollutants; to enhance our understanding of the health effects in susceptible
individuals over time periods when there are large fluctuations in
pollutants compared with normal controls and to identify health outcomes of
air pollution; and to estimate economic loss due to both physical and mental impacts of air
pollution and examine how Beijing can improve its air quality more cost-effectively.
The APHH-Beijing programme has four themes to address the specific
objectives outlined in Sect. 2 and is delivered through five
inter-related research projects:
Theme 1 – sources and emissions: delivered by the AIRPOLL-Beijing (Source
and Emissions of Air Pollutants in Beijing) project; Theme 2 – atmospheric processes: delivered by the AIRPRO (The integrated
Study of AIR Pollution PROcesses in Beijing) project; Theme 3 – health effects: delivered by two projects – the AIRLESS (Effects
of AIR pollution on cardiopuLmonary disEaSe in urban and peri-urban
reSidents in Beijing) and the APIC-ESTEE (Air Pollution Impacts on
Cardiopulmonary Disease in Beijing: An integrated study of Exposure Science,
Toxicogenomics and Environmental Epidemiology) projects; and Theme 4 – solutions: delivered by the INHANCE (Integrated assessment of the
emission-health-socioeconomics nexus and air pollution mitigation solutions
and interventions in Beijing) project.
Theme 1 (AIRPOLL) aims to quantify the emission fluxes of key air pollutants in Beijing and the contributions of different sources, economic sectors and regional transport to air pollution in Beijing. The project has carried out two major field observation campaigns jointly with the AIRPRO and AIRLESS projects (Sect. 3.1.2 and 3.1.3) during November–December 2016 and May–June 2017. The campaigns were carried out at two sites – one within Beijing (at the Institute of Atmospheric Physics (IAP) meteorological tower site) and the other in the local region (the rural Pinggu site; see Sect. 4.1 for site information).
During the intensive campaigns, the project measured the fluxes of particulate and gaseous air pollutants from ground-level sources by sampling on the meteorological tower (325 m) at the IAP site, which is compared with emissions estimates taken from the inventory for Beijing. This was complemented by top-down fluxes inferred from satellite data for nitrogen dioxide, sulfur dioxide and formaldehyde, the latter indicative of volatile organic compound (VOC) oxidation processes (Palmer et al., 2003; Fu et al., 2007). Through these means, the emissions inventory is being tested, allowing revisions which are being incorporated into the atmospheric modelling work.
AIRPOLL also made very detailed online and offline measurements of
airborne particles. This included continuous measurements of size
distributions from 1 nm to > 10
During the campaigns, AIRPOLL and AIRLESS measured the concentrations of key tracers and reactive species indicative of sources and chemical pathways at the ground-level sites, which complements AIRPOLL observations.
Theme 2 (AIRPRO) aims to study the fundamental chemical and physical processes controlling gas and particle pollution, localised meteorological dynamics and the links between them within Beijing's atmosphere. Central to the project were the intensive in situ measurements at the IAP meteorological tower (325 m) site, jointly carried out with the AIRPOLL project. AIRPRO made comprehensive and detailed local observations of both primary emitted chemicals and particles, radical intermediates and secondary products, for periods of contrasting local and regional emissions, solar insolation and air temperature. These data allow the performance of local and regional models of air pollution to be robustly tested, both for final regulated pollutant outcomes and at a more mechanistic level.
Observations made with instruments from multiple Chinese and UK research
groups included complementary measurements of key precursor trace gases such
as
The IAP tower allowed vertical profiles of key pollutants up to 320 m to be obtained and, with additional remote sensing of composition and meteorology, provided insight into boundary layer stability and evolution over the diurnal cycle. Quantification of shallow mixed layers proved to be vital for explaining local surface in situ chemical processing and also street-level concentrations of relevance to exposure. The potentially significant vertical gradients anticipated in some chemicals and PM properties were further quantified using instruments installed on the tall tower and via profiling gondola measurements. The combined datasets, surface and profiles provide the basis for evaluation of model performance and notably comparisons for those intermediates that provide indicators of whether secondary pollution production is being correctly simulated.
Health effects of air pollution are studied by two projects – AIRLESS and APIC-ESTEE. AIRLESS aims to advance air quality and health research in Beijing by bringing together two fields of research that have made rapid advancements in recent years: measurements of a wide range of pulmonary and cardiovascular biomarkers in a panel study and personal monitoring of multiple air pollutants with high spatiotemporal resolution by sensor technology. AIRLESS is also benefiting from the use of an extensive range of pollution metrics and source apportionment results from the AIRPOLL and AIRPRO projects. These data are being compared with our personal air quality assessments and used to further understanding of the nature of the air pollution exposures of residents and how this relates to their health status.
APIC-ESTEE aims to evaluate the impacts of air pollution on cardiopulmonary health through an integrated study of exposure, epidemiology and toxicology/toxicogenomics. APIC-ESTEE has investigated the relationship between ambient air pollution and personal exposures. This is being used to estimate personal exposures for epidemiological analyses of long-term health impacts in a cohort study and of short-term effects (i.e. biomarkers, blood pressure, heart rhythm and peak flow) in a panel study. APIC-ESTEE also studied the real-world exposure reduction and health benefit potential of face masks, a commonly used personal-level intervention seen in Beijing. Furthermore, to complement the human based studies into mechanisms of action, APIC-ESTEE has conducted in vivo analyses of mechanistic effects and early life toxicogenomics/metabonomics.
Theme 4 (INHANCE) aims to quantitatively evaluate the performance of China's current air pollution policies and develop cost-effective solutions to mitigate the impact of air pollution in the Beijing megacity. INHANCE considered not only the physical and mental health impacts and direct economic impact but also the cascading indirect economic losses that occurred through inter-industrial and inter-regional linkages on the supply side of the economy. INHANCE has established and evaluated interactive relationships among exposure, vulnerability, impact on health, implications for industry and economic consequences. INHANCE has compared and qualitatively assessed air quality policies between Beijing and other cities, undertaken policy performance assessment modelling, utilised techno-economic inventories for anti-pollution measures to conduct microeconomic cost–benefit analysis of new policies, measured health and macroeconomic costs and benefits in mitigating air pollution, and transformed evidence generated into practical emission alleviation pathways. On these bases, INHANCE will deliver recommendations regarding integrated policy design and an assessment for policy cost-effectiveness.
The APHH-Beijing programme is highly integrated to ensure the biggest possible scientific and policy impacts. One of the most significant integration activities between the different themes is the coordinated joint field campaigns at an urban and a rural site in Beijing for Themes 1, 2 and 3 to fully exploit the complementary measurements and expertise by different research groups, which is described in the following sections. Themes 1 and 2 are closely related and in many senses inseparable. For example, our knowledge of the sources and emissions is essential to interpret the processes, while knowledge on the atmospheric physical and chemical processes will help us to more accurately quantify the source emissions both via actual flux-based measurements and model evaluation of the emission inventories. Furthermore, to ensure integration, Themes 1 and 2 co-located their rural site at Pinggu as that was selected for the Theme 3 panel study.
Modelling of airborne concentrations of pollutants within Themes 1 and 2 is fully integrated, primarily via the UKCA (UK Chemistry and Aerosol), NAQPMS (Nested Air Quality Prediction Model System) and GEOS-Chem models. The models simulate spatial and temporal variations of key air pollutants and are being evaluated using the new observations of pollutant emission fluxes, updated emission inventories, three-dimensional air quality low-cost-sensor observations, comprehensive composition and physics measurements, as well as new process understandings generated from the APHH-Beijing programme. Furthermore, in Themes 1 and 2, ADMS (Atmospheric Dispersion Modelling System) modelling results for the campaign periods facilitate the estimation of population exposure in Theme 3. Outcomes of Themes 1, 2 and 3 help to provide Theme 4 with a more accurate estimate of pollution costs and to develop cost-effective air pollution control measures in Beijing.
The third stream of integration activities involves regular APHH-Beijing
programme science and stakeholder engagement meetings to stimulate
collaboration and knowledge transfer between different themes and
stakeholders. Furthermore, sharing of data was made available via a
dedicated depository in Centre for Environmental Data Analysis (
Together, this interdisciplinary APHH-Beijing programme delivers key
scientific values and innovation, including
validation of the bottom-up emission inventories by using novel eddy
covariance emission flux observations from the IAP meteorological tower,
integrated with satellite retrievals and numerical modelling; improvement in understanding of air pollution processes through
comprehensive observations of atmospheric gaseous and aerosol species
integrated with atmospheric physics measurements; and identification of the sources of air pollution that cause largest
adverse human health effects by carrying out novel cardiovascular health
indicator measurements, integrated with personal exposure, fixed station
source apportionment studies and high-resolution air quality modelling.
The two intensive campaigns took place from 10 November to 10 December 2016 and 20 May to 22 June 2017. The campaigns were carried out at both urban and rural sites.
Study area topography (source: Google Maps) of the Beijing–Tianjin–Hebei region
The winter campaign had two main sites. The urban site (39
The rural Pinggu site in Xibaidian village (40.17
In the summer, an additional site was operated in Gucheng (39.2
In addition to the two highly instrumented urban (IAP) and rural (Pinggu)
sites, 21 SNAQ (Sensor Network for Air Quality) boxes, which measure CO, NO,
Figure 1 also shows the location of the 12 national air quality monitoring
stations. Hourly data for criteria air pollutants (PM
Table 1 lists all instruments deployed during the campaigns at the IAP site. Most instruments ran during both campaigns. A majority of the instruments were situated in the nine containers, which were at ground level on the campus grass. A number of online instruments and high-volume PM samplers were also deployed at different heights on the meteorological tower. Vertical profile measurements of atmospheric species including HONO were made during pollution events using baskets attached to the tower. Additional online measurements and offline PM samplers were deployed at ground level, on the roof of a two-storey building to the west (WB) and in a third-floor laboratory at the south end of the campus. In addition, high-, medium- and low-volume PM samplers were placed on the roof of WB for offline characterisation and source apportionment.
Overview of measurements in APHH-Beijing at the urban site.
Continued.
Continued.
Institution names: AIOFM is Anhui Institute of Fine Optics and
Mechanics; BNU is Beijing Normal University; CEH is Centre for Ecology and
Hydrology; CUMTB is China University of Mining and Technology (Beijing); GIG
is Guangzhou Institute of Geochemistry, Chinese Academy of Sciences; NUIST
is Nanjing University of Information Science and Technology; IC-CAS is
Institute of Chemistry, Chinese Academy of Sciences.
At Pinggu, online instruments (Table 2) were run within an air-conditioned room on the ground floor with inlets on top of the building. High-, medium- and low-volume PM samplers were deployed on a newly modified flat roof of the single-storey building.
At Gucheng (summer only), a high-volume Digitel sampler and a single
particle sampler were set up on a deserted basketball court. An aethalometer
AE33 was located on top of a container at the edge of the basketball court.
CO and
Overview of measurements at the Pinggu site.
CQIGIT is Chongqing Institute of Green and Intelligence Technology, Chinese Academy of Sciences.
Synoptic circulation patterns (e.g. horizontal advection and wet deposition) play a key role in the variations of air quality in Beijing (Miao et al., 2017; Wu et al., 2017; Zhang et al., 2012). To provide the synoptic context of the APHH-Beijing observations, the daily mesoscale flow patterns have been classified and put into context using a 30-year climatology (Sect. 5.4).
Circulation types (CTs) are classified using the software produced by the
COST Action 733 “Harmonisation and Applications of Weather Type
Classifications for European regions”
(Philipp et al., 2010) with (ECMWF
reanalysis) ERA-Interim 6 h 925 hPa geopotential reanalysis data
(Dee et
al., 2011) at its native 0.75
ERA-Interim (1988–2017) average 925 hPa geopotential with
10 m horizontal wind vector for 11 circulation types classified for Beijing
(municipal boundary; thin solid line) surroundings (31–49
Mean and standard deviation (SD) of climatological
conditions in Beijing for each circulation type (CT) for 1988–2017 from
ERA-Interim data with frequency (%) of the CT during the
Note: WS – wind speed, WD – wind direction, T2m – 2 m air temperature, TD2m –
2 m dew-point temperature, MSLP – mean sea level pressure, RH – relative
humidity;
As expected, the CTs that occurred during the two field campaign periods are different (Fig. 3). During the winter field campaign, the most frequent circulation type was CT 11 (26 % of the 6 h periods) which was often preceded by a period of CT 9 (total 13 %). Circulation types 9–11 are associated with air masses that may stagnate over the Beijing urban area (Fig. 2). CT 1 (accounting for 12 % of the time) and CT 2 (17 %) are associated with the Asian winter monsoon which brings cold and dry air masses to eastern China. North-westerly flow (over Beijing) is driven by high pressure in the west of the domain (Fig. 2). These are followed by CTs 5, 3 and 7, occurring 14 %, 7 % and 4 % of the time, respectively. CTs 3 and 5 are associated with relatively low pressure in the north-east (September–May period), while CT 7 has a south-easterly winds from the Bohai Sea. CTs 4, 6 and 8 did not occur during the winter campaign.
Time series of circulation types (CTs) during the two
field campaigns:
During the summer campaign (Fig. 3b), the most frequent CTs were 8, 7, 4 and 6 (33 %, 25 %, 19 % and 10 % of the time, respectively). CTs 8 and 6, which did not occur during the winter campaign period, are associated with the summer monsoon, advecting moist, warm air from the south and south-east (Fig. 2). While southerly and northerly flows converge over Beijing for CT 6, slightly weaker low pressure to the north-east means north-westerly flow dominates for CT 4. High pressure to the west or south of Beijing is rare during the summer campaign, so that CTs 1, 2, 9 and 11 do not occur, and CTs 3 and 5 are rather rare (5 % and 1 %, respectively).
To assess how local-scale flow related to ERA-Interim fields (Sect. 4.3) compared to local conditions, the link between the coarse gridded data and tower-based sonic anemometer observations is explored based on wind roses (Fig. 4). The 30-year climatology (Fig. 4a, d) confirms the clear seasonality in wind direction affecting the occurrence of CTs discussed (Sect. 4.3); i.e. during the winter intensive campaign period (10 November–10 December), north-easterly flow clearly dominates, while southerly wind directions are most common during the summer campaign period (20 May–22 June). The wind roses for winter 2016 and summer 2017 (Fig. 4b, e) are slightly noisier but show similar tendencies to the climatology. The general large-scale patterns are consistent with the in situ wind measurements (Fig. 4c, f). However, a slight diversion towards northerly and south-westerly flow and lower wind speeds occurred in winter and summer (Fig. 4c and f), respectively, when compared to the larger-scale data (Fig. 4b and d). In addition, south-westerly flows were more frequent in winter 2016 (Fig. 4b and c) than during the 30-year average climatology (Fig. 4a), which had the potential to bring more polluted air in the upwind Hebei province to the observation sites in Beijing.
Beijing wind roses:
At 102 m, the flow is consistent with northerlies and north-westerlies in
the winter campaign and dominantly southerly and easterlies during the
summer campaign (Fig. S1 in the Supplement). The measured hourly mean wind speed,
temperature and relative humidity were 3.1 m s
Time series of air quality variables at the urban and rural sites during the winter campaign. Five haze events are indicated (shading; see also Table 4).
During the winter campaign, the daily average concentration of PM
Average air quality variables at IAP, Pinggu and 12
national monitoring sites (12N) during the field campaigns (10 November–11 December 2016; and 21 May–22 June 2017). The 12 national sites
5-year mean concentrations for same times of the years (12N-5Y) and for
the same time of the year (campaign period) (12N-campaign) are shown. Data are mean
Haze periods during the summer and winter campaign periods.
Note: data in parentheses show the hourly range.
The daily average concentration of PM
Diurnal cycles of particles,
Diurnal patterns of gaseous pollutants normalised by average concentrations at IAP during winter and summer campaigns. The line shows the mean concentrations and shaded area as 95 % confidence interval in the difference in mean concentrations.
Variations of particles,
SNAQ box measurements at six levels (8 to 320 m) during the winter campaign
(Fig. 7) have similar overall temporal patterns of CO and NO to that
measured by standard gas analyser (Fig. 5). In most cases, the air
pollutant levels are similar at different levels of the tower. There are
notable differences in NO, CO and
Time series of
According to the meteorological standards (QX/T113-2010), haze is defined
as (i) visibility < 10 km at relative humidity (RH) < 80 %
or (ii) if RH is between 80 and 95 %, visibility < 10 km and PM
Characteristics of five major haze events during the winter campaign (Fig. 5) show that PM
Concentrations of air pollutants excluding ozone during the summer campaign
were much lower than in winter (Fig. 8, Table 4). Average daily
concentration of PM
Time series of air quality variables at the urban and rural sites during the summer campaign. Two minor haze events are indicated (shading).
Diurnal patterns of NO,
Characteristics of two minor haze events (IAP) during the summer campaign (Fig. 8) are shown in Table 5.
To assess if the IAP air quality is broadly representative of the wider
Beijing megacity, air quality parameters at the 12 national air quality
stations were correlated with each other (Fig. 9). A high correlation is observed with PM
In general, PM
Correlations between the air quality at IAP, PQ and 12 monitoring station around Beijing. Stations G1–G12 (Fig. 1b) are labelled 01–12; PG is Pinggu.
The PM
Table 4 shows that the IAP concentration data for all air quality variables are very close to the 5-year mean of the 12 national air quality monitoring stations. This lends further confidence that the chosen urban site represented well the overall pollution levels in the Beijing urban area.
The average mixed layer height observed at IAP varies with season and CT
type (Fig. 10a). Lower mixed layer height is usually linked to air
pollution events. The 11 CTs (Sect. 4.3) are clearly associated with
distinct air quality conditions based on analysis of hourly air quality data
for 2013–2017 at one of the national urban air quality stations (G11,
Olympic Park; Fig. 1). Relatively low wind speeds of CT 7 may contribute
to the long haze event from 15 to 19 November 2016 (Fig. 5). Most haze
events during the winter campaign are cleared out by fresh air masses being
advected from the north in CTs 3 or 5 (Fig. 3), which is also marked by
the increase in wind speed observed (Fig. S1). Relatively lower PM
Analysis by circulation type (CT; Sect. 4.3)
of
In the October 2016–September 2017 period (Fig. 10e), the relative frequency of
CTs differs slightly from the long-term climatology (Fig. 10d). During the
winter campaign, clean air advection from the NE (CTs 1–3) was less frequent
than in the 30-year climatology. Given synoptic circulation types associated
with stagnation do have a similar occurrence during the winter campaign
compared to the same time period within the previous 5 years (with CT 9
being 8 % less frequent and CTs 10 and 11 being 2 % and 10 % more frequent; Fig. 10f), PM
Comparison of observed (at IAP) and modelled pollutant
concentrations showing
Frequency distribution of PM
In summary, the winter campaign was characterised by several high PM
Air quality modelling is a key component of the APHH-Beijing programme. A range of models have been applied that span global (UKCA, GEOS-Chem), regional (WRF-Chem, CMAQ, NAQPMS) and urban to street scales (ADMS). This section provides an example of the comparison between model-simulated pollutant concentrations and APHH-Beijing observations made at IAP to demonstrate model capabilities. Results from specific modelling studies will be published separately.
Figure 11a shows that the magnitude and variation of wintertime PM
We also investigated how representative the campaign periods were of the
selected seasons in Beijing by comparing pollutant levels with those from
the same period each year over the 2013–2017 period. The NAQPMS model was
run for the full 5-year period driven by NCEP meteorology and using
temporally varying emissions for a single year that is broadly
representative of 2013 conditions. The same emissions were used each year so
that the meteorological contribution to pollutant levels could be assessed.
This provides important information that cannot be obtained from the
monitoring data (as emission varies year by year). The frequency
distribution of PM
APHH-Beijing is an integrated and multidisciplinary research programme conducted by leading UK and Chinese researchers to (1) quantify sources and emissions of urban atmospheric pollutants; (2) elucidate processes affecting urban atmospheric pollution events; (3) estimate the personal exposure and impacts of air pollution on human health and (4) develop intervention strategies to improve air quality and reduce health impacts in the Beijing megacity. This introduction paper outlines the motivation of the APHH-Beijing programme and provides the background air quality and meteorological conditions during the two intensive field campaigns that form the basis of data interpretation for campaign observations.
APHH-Beijing has measured the fluxes of key air pollutants, including
Data are available at
The supplement related to this article is available online at:
ZS drafted the manuscript and is the science coordinator of the APHH-Beijing programme. RMH, KBH, ACL, PQF, TZ, FJK, ML, ZWS, DBG and ST are the lead PIs of the five research projects who led the funding applications and the research. They also drafted Sect. 2. TV plotted many of graphs and carried out the data analysis. SK, SG and MD carried out analysis and wrote Sects. 4.3 and 5.4; and YLW, MH, ZFW and OW carried out modelling and plotted Figs. 11 and 12. PFQ, JL and ZT led the air quality measurements at the two measurement sites. SY, JL, RED, LR, DL, JA, DB, WJ, LC, LC, HC, TD, FKD, BZG, JFH, MH, DH, CNH, MH, DSJ, XJJ, RJ, MK, LK, BL, LC, JL, WJL, KDL, GM, MM, GM (Mills), JA, XFW, EN, BO, CP, PIP, OP, CR, CY, FL, JG, JC, LYS, YS, SRT, QQW, WHQ, XMW, ZFW, LW, XFW, ZJW, PHX, FMY, QZ, YLZ and MZ contributed to the field observations, laboratory measurements and/or modelling. ZS, SG, RMH, ZT, JL, OW, JA, JB, WJB, DC, DCC, HC, TD, RD, FKD, PQF, MFG, DBG, JFH, KBH, MH, DH, CNH, MH, XJJ, RJ, MK, FJK, LK, ACL, JL, ML, KL, GrM, GoM, MM, PM, EN, FO, PIP, CP, CR, ARR, LYS, GYS, DoS, DaS, YS, XJW, JFL, BB, QC, ZWS, ST, SRT, XMW, ZFW, LW, ZJW, PHX, QZ, YHZ and MZ contributed to the funding applications, programme meetings and relevant programme research and/or supervision.
The authors declare that they have no conflict of interest.
This article is part of the special issue “In-depth study of air pollution sources and processes within Beijing and its surrounding region (APHH-Beijing) (ACP/AMT inter-journal SI)”. It is not associated with a conference.
Funding is provided by UK Natural Environment Research Council, Medical Research Council and Natural Science Foundation of China under the framework of Newton Innovation Fund (NE/N007190/1 (Roy M. Harrison, Zongbo Shi, William J. Bloss); NE/N007077/1 (William J. Bloss)); NE/N00700X/1 (Sue Grimmond), NE/N007018/1 (Frank J. Kelly); NSFC Grant 81571130100 (Tong Zhu), NE/N007115/1 (Alastair C. Lewis, Andrew R. Rickard, David C. Carslaw); NE/N006917/1 (James Lee, Jacqueline F. Hamilton, Rachel E. Dunmore); NE/N007123/1 (James Allan, Carl Percival, Gordon McFiggans, Hugh Coe); NE/N00695X/1 (Carl Percival, Hugh Coe, Gordon McFiggans, James Allan); NE/N006976/1 (C. Nicholas Hewitt, Oliver Wild); NE/N006925/1 (Oliver Wild); NE/N006895/1 (Dwayne Heard, Lisa Whalley); NE/N00714X/1 (Daobo Guan), NE/N007182/1 (Miranda Loh); NSFC 41571130024 (Pingqing Fu) and NE/N006879/1 (Paul I. Palmer). Other Grant supports from Newton Fund/Met Office CSSP-China (Sue Grimmond; Ruth Doherty and Zongbo Shi), Royal Society Challenge Grant (CHG/R1/17003, Paul I. Palmer) and NERC (NE/R005281/1, Zongbo Shi) are acknowledged. Field help from Hong Ren, Qiaorong Xie, Wanyu Zhao, Linjie Li, Ping Li and Shengjie Hou from IAP, Kjell zum Berge, Ting Sun at Reading University, Wu Chen, Yanwen Wang, Yunfei Fan, Teng Wang, Xi Che, Tao Xue, Pengfei Liang, Yingruo Li, Xinyan Hu and Xinghua Qiu from Peking University, Li Yan, Hanbin Zhang, Yutong Cai and Bingling Zhou from King's College London, Anika Krause from Cambridge University is also acknowledged. Many other staff and students from different institutions also contributed to the field campaigns and programme.
This research has been supported by the Natural Environment Research Council (grant nos. NE/N007190/1, NE/N007077/1, NE/N00700X/1, NE/N007018/1, NE/N007115/1, NE/N006917/1, NE/N007123/1, NE/N00695X/1, NE/N006976/1, NE/N006895/1, NE/N00714X/1, NE/N007182/1, NE/N006925/1, NE/N006879/1, NE/R005281/1, and NE/N006879/1), the National Natural Science Foundation of China (grant nos. 81571130100 and 41571130024) and the Royal Society (grant no. CHG/R1/17003).
This paper was edited by Delphine Farmer and reviewed by three anonymous referees.