Tackling the health burden of air pollution in South Asia

Abstract

Air pollution exposure is the second
most important risk factor for
ill health in South Asia, contributing
to between 13% and 21.7%
of all deaths and approximately
58 million disability adjusted life years
(DALYs) through chronic and acute respiratory
and cardiovascular illnesses.1 Of the
top 30 cities in the world with the poorest
air quality in 2016, 17 are in South Asia.2
The impact of air pollution transcends
boundaries. The “brown cloud”—caused
by pollution from carbon aerosols—is a
phenomenon captured in satellite images of
atmospheric haze over South Asia, as well
as China. South Asia has one of the highest
concentrations of black carbon emissions
from cars and trucks, cooking stoves, and
industrial facilities. In addition to their
effect on health, black carbon particles are
a short lived climate pollutant with a possible
impact on precipitation patterns and
on the Himalayan glacier system, which
threatens water resources in the region.3
Collective regional action to monitor air
quality and implement evidence based
policies and interventions is needed.
While countries have introduced promising
initiatives in recent years, comprehensive
health centred strategies are lacking. We
present the status of air pollution and
health effects in South Asia, and propose
urgent, concerted action across sectors to
achieve recommended air quality standards
for the people of the region.

Full text

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2017;359:j5209 | doi: 10.1136/bmj.j5209 1
ANALYSIS
Tackling the health burden of air pollution
inSouth Asia
Bhargav Krishna and colleagues call for health driven, multisectoral policy making with defined
air quality targets to curb the impact of air pollution exposure in South Asia
KEY MESSAGES
•
Air pollution is a major risk factor for
ill health in South Asia
•
The interconnected nature of the
South Asian airshed necessitates
regional cooperation
•
Tackling the sources of air pollution
requires systematic collection of air
quality data and a scientic approach
to air quality management
•
Tackling the health burden of air pol-
lution will require coordinated, multi-
sectoral response, using a “health in
all policies” framework
A
ir pollution exposure is the sec-
ond most important risk factor for
ill health in South Asia, contrib-
uting to between 13% and 21.7%
of all deaths and approximately
58 million disability adjusted life years
(DALYs) through chronic and acute respir-
atory and cardiovascular illnesses.1 Of the
top 30 cities in the world with the poorest
air quality in 2016, 17 are in South Asia.
2
The impact of air pollution transcends
boundaries. The “brown cloud”—caused
by pollution from carbon aerosols—is a
phenomenon captured in satellite images of
atmospheric haze over South Asia, as well
as China. South Asia has one of the highest
concentrations of black carbon emissions
from cars and trucks, cooking stoves, and
industrial facilities. In addition to their
eect on health, black carbon particles are
a short lived climate pollutant with a pos-
sible impact on precipitation patterns and
on the Himalayan glacier system, which
threatens water resources in the region.3
Collective regional action to monitor air
quality and implement evidence based
policies and interventions is needed.
While countries have introduced promising
initiatives in recent years, comprehensive
health centred strategies are lacking. We
present the status of air pollution and
health eects in South Asia, and propose
urgent, concerted action across sectors to
achieve recommended air quality standards
for the people of the region.
Air pollution exposure and trends
Household (indoor) and ambient (outdoor)
air pollution both contribute to ill health.
Rural and urban areas are both aected
by poor air quality. However, the sources
and pollutant proles vary. For instance,
use of cooking fuels varies between urban
and rural households, vehicular density is
higher in cities, and dierent climate and
geography across the region aect levels of
air pollution.
Household air pollution
Approximately 74% of South Asian house-
holds use solid fuels such as wood, dung,
or coal for cooking and heating.4-6 These
are inecient fuels and their use in open
fires or leaky stoves contributes to high
levels of indoor smoke. Studies on indoor
air pollution in South Asia show average
daily PM
2.5
concentrations range from 300
μg/m3 to 3000 μg/m3, 5 7 8 which is much
higher than is recommended by the World
Health Organization (box 1).9 The propor-
tion of households relying on solid fuels
has decreased over the past few decades
(g 1); however this decrease has largely
been oset by the increase in population.
10
The type of fuel and stove, kitchen area
ventilation, quantity of fuel, age, gender,
and time spent near the cooking area
influence exposure within and between
households. Women and children tend
to have higher exposure. Use of solid
cooking fuels also contributes to ambient
air pollution as a result of emissions
carried outdoors. In densely populated
communities of India, household air
pollution has been estimated to contribute
to nearly 27% of ambient air pollution.11
Since few studies report direct measures
of household air pollution,7 trends are
estimated (for purposes of comparative
risk assessment) using spatiotemporal
Gaussian process regression modelling that
incorporates data on the proportion of solid
fuel use in each country from nationally
representative household surveys and
select co-variates, including maternal
education and proportion of population
living in urban areas12
Ambient air pollution
The population in South Asia, with the
exception of Sri Lanka, is among the
most highly exposed to PM
2.5
in the world
(table1). Estimates from the Global Burden
of Disease Study 2015 (GBD) indicate that
the population weighted mean ambient
PM2.5 concentration in South Asia* was 73
μg/m
3
, compared with the global average of
44 µg/m
3
. Nearly 99.9% of the South Asian
population is living in areas with poorer air
quality than the minimum standards rec-
ommended by WHO (box 1).
Population weighted PM2.5
concentrations have increased by 24% in
South Asia between 1990 and 2015, with
an increase in all countries except Pakistan
and Sri Lanka (g 2). Ozone concentrations
Box: Air quality standards recommended by WHO
PM (g/m)PM. (g/m)
Annual mean
concentration
 h
concentration
Annual mean
concentration
 h
concentration
Interim target-1 70 150 35 75
Interim target-2 50 100 25 50
Interim target-3 30 75 15 37.5
Air quality guideline* 20 50 10 25
1 PM10: Airborne particulate matter smaller than 10 μm (includes both coarse and ne particles that enter the respiratory tract).
2 PM2.5: Airborne particulate matter smaller than 2.5 μm.
3 Interim targets represent incremental steps in a progressive reduction of air pollution. Annual mean concentrations
provide an estimate of long term exposure for comparison.
4 *Lowest levels at which total, cardiopulmonary, and lung cancer mortality have been shown to increase in response to
long term exposure to PM2.5.
Fig1 | Trends in estimated percentage of
households using solid fuels in South Asian
countries

2 doi: 10.1136/bmj.j5209 |
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2017;359:j5209 | thebmj
ANALYSIS
have also increased across the region at a
rate exceeding the global increase.
The sources of ambient air pollution
vary across the region, and across rural
and urban settings. Vehicular emissions,
construction and road dust, residential
biomass use, and industrial emissions are
major contributors.13-16 The main sources
of fuel used for power generation such as
coal, natural gas, and oil can influence
air quality. In Bangladesh, localised
sources like brick kilns and motorised
transport contribute to the base pollution
load throughout the year. Additionally,
in winter, transboundary transport of
particulate matter across the Indo-Gangetic
Plain airshed contributes to higher
levels of PM2.5.14 Similarly, in Pakistan,
transboundary transport of dust and
pollutants from the Arabian Peninsula
15 16
and from India17 is noted to cause episodic
spikes in PM10 and PM2.5 levels.
Impact on health
Exposure to ambient PM2.5 was the third
ranking risk factor for mortality (1.4 mil-
lion deaths, 10.6% of total deaths) and
DALYs (5.8% of total DALYs) in South Asia
in 2015. Household air pollution ranks
fourth (5.5% of DALYs and 1.2 million
deaths, 9.6% of total deaths).
18
No studies
to date have evaluated the health impacts
of co-exposure to household and ambient
air pollution.
Over the past 25 years, deaths
attributable to ambient PM2.5 exposure
have increased, with some acceleration
since 2010 (g 3). Increase in PM
2.5
levels,
population growth, and ageing contribute
to this trend. Bangladesh, India, and
Pakistan have a higher burden because
of larger populations, high exposures,
and increasing numbers of people
affected by chronic diseases. Common
diseases aected by air pollution include
ischaemic heart disease, stroke, acute
lower respiratory infections, chronic
obstructive pulmonary disease, and lung
cancer. Deaths attributable to household air
pollution have remained high and relatively
stable with only a modest increase from 1.1
million to 1.2 million between 1990 and
2015.
The age standardised attributable
death rates indicate a small decrease,
from 158 deaths per 100 000 in 1990
to 133 per 100 000 in 2015, while there
has been a large decrease in the rate of
attributable DALYs (g 4) between 1990
and 2010, possibly driven by a decrease
in the incidence of acute lower respiratory
infections. Deaths attributable to ozone
exposure, while much lower than those
attributable to PM2.5 exposure, have
increased sharply throughout South Asia
from 48 000 in 1990 to 122 000 in 2015
(a 154% increase) driven by increased
exposure and increasing rates of chronic
obstructive pulmonary disease in the
region, and in India especially.
Air pollution propagates existing
environmental vulnerabilities.19 Children
and older people are particularly
vulnerable. Air pollution exposure
results in low birth weight,20 poor lung
development in children,
21
mortality from
respiratory infections,
22
and may also aect
cognitive development.23 Older people are
more likely to develop chronic respiratory
and cardiac illnesses, and are more
susceptible to heart attacks and strokes
from long term exposure, and during
episodic high pollution events.24 Lower
socioeconomic groups are more susceptible
to insults from air pollution exposure for a
variety of reasons including occupation and
housing.2 5 19
Fragmented efforts to reduce air pollution
With the lack of high quality data on air pol-
lution and on health eects in South Asian
countries, interventions are usually ad hoc,
and their impact cannot be assessed. Public
Table | GBD  estimates of exposure to ambient air pollution in South Asia
Country
Population
(millions)
Population weighted
mean annual
ambient PM. ()
Percentage increase in
population weighted mean
annual PM. ( to )
Percentage of population
in  living in areas
exceeding WHO IT-
Population weighted
seasonal mean
ozone ()
Percentage increase in
population weighted seasonal
mean ozone ( to )
India 1282.3 74 23 89.9 76 23
Bangladesh 148.9 89 39 99.9 74 25
Pakistan 202.8 65 −4 94.5 69 17
Nepal 31.3 75 34 90.6 78 26
Bhutan 0.9 56 40 81.6 69 25
Sri Lanka 19.5 28 −7 21.9 54 17
South Asia* 1693.8 73 24 91.2 74 21
Global 7155.5 44 10 50.2 61 7
* Here and elsewhere South Asia refers to the GBD regional denition which includes Bangladesh, Bhutan, India, Nepal, and Pakistan. Data for Sri Lanka added separately. WHO IT-1 is
World Health Organization PM2.5 Interim Target −1 of 35 μg/m3 (annual average).
Fig2 | Trends in annual average population
weighted PM2.5 exposure in South Asia, 1990
to 2015. These gures were adapted from
estimates developed for the Global Burden of
Disease (2015) study
Fig3 | Trends in deaths attributable to
ambient PM2.5 in South Asia, 1990 to 2015.
These gures were adapted from estimates
developed for the Global Burden of Disease
(2015) study.
Fig4 | Trends in age standardised
DALYs/100 000 attributable to ambient
PM2.5 exposure in South Asia, 1990 to 2015.
These gures were adapted from estimates
developed for the Global Burden of Disease
(2015) study

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ANALYSIS
and media attention on levels of air pollu-
tion in South Asian cities have led to spo-
radic measures; however, a robust strategy
with targeted reductions in pollutant levels
is lacking.
Availability and quality of air pollution data
Continuous ground monitoring of air qual-
ity across a range of locations is essential to
understand the concentration of pollutants
at dierent time points and implement con-
trol strategies. South Asian countries lag far
behind global standards in the density and
coverage of air quality monitoring networks.
Routine monitoring of PM2.5 and ozone in
the region is minimal. Epidemiological
studies currently rely on modelled exposure
estimates based on satellite data.
In India, for example, the National
Air Quality Monitoring Program collects
pollutant data twice a week from 629
stations across 264 cities, with 35 cities also
hosting continuous air quality monitoring
stations.
26
Monitoring is restricted to urban
areas with virtually none carried out in rural
areas. There are also challenges with the
data collected, including calibration errors,
gaps in data, and wide variation in uptime
of monitoring stations.
Research on health outcomes
A growing body of literature from South
Asia indicates an association between short
term exposure to air pollution and a range
of health outcomes such as decrease in
lung function, respiratory symptoms, emer-
gency department visits, and mortality. To
date, however, no direct epidemiological
studies of long term exposure to ambient
PM2.5 and mortality from chronic diseases
in South Asia have been published. The evi-
dence on acute and chronic health eects
at the high levels of exposures commonly
encountered in South Asian countries
needs to be strengthened.27 28
Large scale household surveys, census,
and vital registration systems are the
primary sources of data on mortality in
South Asia. Incomplete or inconsistent
recording of cause of death, and structural
deficiencies in data collection result in
under-reporting of deaths, especially
in rural areas, and thereby provide
little understanding of the impact of air
pollution.
Air quality management and exposure
reductions
South Asian countries have taken some
steps to address specic categories of emis-
sions and exposures (table 2) and improve
air quality. There is no coherent strategy,
however, with dened targets for air qual-
ity and regular monitoring to understand
the impact of these measures.29 Political
will and eective governance are central to
tackling the problem.
Health centred environmental policy making
is required
With the multiplicity of sources, modes of
exposure, and complexity of outcomes,
there is no easy solution to the prob-
lem of air pollution in South Asia. While
household air pollution needs targeted
interventions with substitute fuels, tack-
ling ambient air pollution, with its varied
sources, requires a broader approach. Sys-
tematic collection of air quality data and
a scientic approach to air quality man-
agement are essential to tackle the varied
sources of emissions. South Asian countries
can learn from and adapt evidence based
initiatives implemented in other parts
of the world such as the Clean Air Act in
the US
46
and China’s ve year, targeted 10
point action plan to improve air quality
in three provinces.47 Local solutions and
policies must be designed to tackle the
major sources and contributors. Box 2 pro-
vides an example of a recent programme
launched in India to reduce household air
pollutionby expanding access to clean
cooking fuel.
An evidence informed, multisectoral
approach to policy making is required.54
While the health sector can play a
convening role on initiatives to minimise
exposure and ameliorate health impacts,
the onus of action lies outside, with
the implementation of policies and
programmes across the ministries of
environment, energy, industry, and
nance, among others.
The emphasis on “health in all policies”
laid out in the 68th World Health
Assembly’s resolution on air pollution
provides a roadmap to tackle a cross
sectoral issue like air pollution where
health is adversely aected as a result of
ineective policy making across sectors.
The resolution emphasised the need for
health related benchmarks of progress
in air pollution control measures, and
advocated health impact assessments
in policy design, implementation, and
evaluation related to air pollution.55 In
the context of growing energy use, rapid
urbanisation, and increased demand for
personal and public transport, the health
Table | Sector specic policies and interventions undertaken to reduce emissions and
exposures
Country Target sector Policies or interventions
Pakistan30-34 Transport Introduction of Euro IV standards for exhaust emissions from passenger cars
Retrofitting diesel buses and trucks with PM emission controls
Power Coal gasification, carbon sequestration
Industry Gas to replace fuel oil and coal
Low sulphur furnace oil and diesel
Domestic Promote cleaner cooking and increased use of natural gas
India35-40 Transport Introduction of Euro VI equivalent standards for vehicles and fuels
Industry and power Emissions standards for various industries
Domestic LPG connections to 50 million rural households by 2019
Localised
action plans
Graded Response Action Plan for Delhi
Comprehensive Action Plan for pollution control in the National Capital Territory
Brick kilns Transition to “induced draft zig-zag” technology
Bangladesh41-43 Transport Ban on 2-stroke engines, introduction of compressed natural gas vehicles in Dhaka
Brick kilns Introduction of Hybrid Hoffman kilns
Multiple sectors Air Pollution Reduction Strategy for Bangladesh
Sri Lanka44 Transport Phasing out 2-stroke engines
Introduction of vehicular testing programmes
Nepal45 Transport Vehicle inspection and emissions testing
Ban on 2-stroke engines
Pollution cess on fuel
Brick kilns Ban on movable bull trench kilns
Dust control Road improvement and footpath development in Kathmandu
Box: Increasing access to clean cooking fuel in India
The Indian government has historically provided a subsidy for liquefied petroleum gas (LPG).
Access to this subsidy, however, was skewed heavily in favour of the urban population.48
To tackle this imbalance, the Pradhan Mantri Ujjwala Yojana was launched in May 2016 with
the aim of providing 50 million rural households with subsidised LPG connections by 2019,
where hitherto they had been using solid fuels for cooking (fig 5).
This was coupled with a campaign to encourage urban recipients to give up their subsidy, and
the PAHAL scheme for direct transfer of LPG subsidies to beneficiaries’ bank accounts.49 50 The
programme exceeded its connection targets in the first year.51 The investment both by way
of political will and finances is vital. The question, however, of whether access equates with
usage remains—newspapers have recently reported on beneficiaries dropping out after initial
refills.52 53

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ANALYSIS
impacts of air pollution can be a conscience
keeper for the principles of sustainable
urbanisation and development.
While localised sources and emissions
are important to tackle exposure, it is
also vital to recognise the role of long
distance and transboundary transport of
air pollution in an interconnected airshed
like the Indo-Gangetic Plain which links
Bangladesh, India, and Pakistan. Existing
political platforms, such as the South Asian
Association for Regional Cooperation,
must be leveraged to drive action on air
quality. WHO’s multisectoral action plan
on non-communicable diseases provides
a platform through which national and
regional consensus can be fostered on
the health impacts of air pollution. In
addition to the nine traditional risk factors
outlined in the action plan, member states
of WHO’s South East Asia region included
the reduction of exposure to household air
pollution from biomass as a target for the
region. This platform can be the basis for
coordinated and innovative regional action
to reduce exposures and improve health
outcomes.
Sources and methods
We used data from the Global Burden of
Disease Study (GBD) 2015 on ambient
and household exposure to air pollution
and health burden estimates. Details on
the methods for exposure estimation are
described elsewhere.29 30
We do not know of any other study
that provides national level estimates
for the purpose of comparison across
different countries. In this context, we
acknowledge the need to strengthen the
local evidence base by conducting more
direct epidemiological studies on the
health eects of ambient and household
air pollution which would accord greater
condence to the burden estimates.
During the preparation of this
manuscript, the GBD estimates for 2016
were released. We believe that the minor
revision in overall numbers did not
necessitate shifting to the 2016 estimates
for this article.
For other information covered in this
article, we conducted searches on PubMed,
Google Scholar, and Science Direct for
relevant reviews and reports published
in the region, and drew on our collective
experience in this eld.
Contributors and sources: BK and DB developed
the outline for the paper, to which all other
authors contributed. BK, MB, KB, ARS, DB, and BAB
contributed sections to the paper, drawing on their
previous work and research from their respective
countries. BK consolidated dras. BK and MB
coordinated revisions. All authors reviewed and
approved the nal manuscript.
Competing interests: We have read and understood
BMJ policy on declaration of interests and have no
relevant interests to declare.
Bhargav Krishna, manager (technical)
Kalpana Balakrishnan, associate dean (research)
and director
Amna R Siddiqui, associate professor
Bilkis A Begum, chief scientic ocer
Damodar Bachani, director
Michael Brauer, professor
1Centre for Environmental Health, Public Health
Foundation of India, Gurgaon, India
2Department of Environmental Health Engineering, Sri
Ramachandra University, Chennai, India
3Department of Community Health Sciences, Aga Khan
University, Karachi, Pakistan
4Chemistry division, Atomic Energy Centre, Dhaka
(AECD), Dhaka, Bangladesh
5School of Population and Public Health, University of
British Columbia, Vancouver, Canada
Correspondence to: Bhargav Krishna
bhargavkrishna@gmail.com
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images/2016/05/PMUY.jpg)

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Cite this as: BMJ ;:j
http://dx.doi.org/10.1136/bmj.j5209