156 research outputs found
Use of spatiotemporal characteristics of ambient PM2.5 in rural South India to infer local versus regional contributions
This study uses spatiotemporal patterns in ambient
concentrations to infer the contribution of regional versus
local sources. We collected 12 months of monitoring data for
outdoor fine particulate matter (PM2.5) in rural southern India.
Rural India includes more than one-tenth of the global
population and annually accounts for around half a million air
pollution deaths, yet little is known about the relative
contribution of local sources to outdoor air pollution. We
measured 1-min averaged outdoor PM2.5 concentrations during June
2015-May 2016 in three villages, which varied in population
size, socioeconomic status, and type and usage of domestic fuel.
The daily geometric-mean PM2.5 concentration was approximately
30mugm(-3) (geometric standard deviation: approximately 1.5).
Concentrations exceeded the Indian National Ambient Air Quality
standards (60mugm(-3)) during 2-5% of observation days. Average
concentrations were approximately 25mugm(-3) higher during
winter than during monsoon and approximately 8mugm(-3) higher
during morning hours than the diurnal average. A moving average
subtraction method based on 1-min average PM2.5 concentrations
indicated that local contributions (e.g., nearby biomass
combustion, brick kilns) were greater in the most populated
village, and that overall the majority of ambient PM2.5 in our
study was regional, implying that local air pollution control
strategies alone may have limited influence on local ambient
concentrations. We compared the relatively new moving average
subtraction method against a more established approach. Both
methods broadly agree on the relative contribution of local
sources across the three sites. The moving average subtraction
method has broad applicability across locations
Predictors of Daily Mobility of Adults in Peri-Urban South India
Daily mobility, an important aspect of environmental exposures
and health behavior, has mainly been investigated in high-income
countries. We aimed to identify the main dimensions of mobility
and investigate their individual, contextual, and external
predictors among men and women living in a peri-urban area of
South India. We used 192 global positioning system
(GPS)-recorded mobility tracks from 47 participants (24 women,
23 men) from the Cardiovascular Health effects of Air pollution
in Telangana, India (CHAI) project (mean: 4.1 days/person). The
mean age was 44 (standard deviation: 14) years. Half of the
population was illiterate and 55% was in unskilled manual
employment, mostly agriculture-related. Sex was the largest
determinant of mobility. During daytime, time spent at home
averaged 13.4 (3.7) h for women and 9.4 (4.2) h for men. Women's
activity spaces were smaller and more circular than men's. A
principal component analysis identified three main mobility
dimensions related to the size of the activity space, the
mobility in/around the residence, and mobility inside the
village, explaining 86% (women) and 61% (men) of the total
variability in mobility. Age, socioeconomic status, and
urbanicity were associated with all three dimensions. Our
results have multiple potential applications for improved
assessment of environmental exposures and their effects on
health
Development of land-use regression models for fine particles and black carbon in peri-urban South India
Land-use regression (LUR) has been used to model local spatial
variability of particulate matter in cities of high-income
countries. Performance of LUR models is unknown in less
urbanized areas of low-/middle-income countries (LMICs)
experiencing complex sources of ambient air pollution and which
typically have limited land use data. To address these concerns,
we developed LUR models using satellite imagery (e.g.,
vegetation, urbanicity) and manually-collected data from a
comprehensive built-environment survey (e.g., roads, industries,
non-residential places) for a peri-urban area outside Hyderabad,
India. As part of the CHAI (Cardiovascular Health effects of Air
pollution in Telangana, India) project, concentrations of fine
particulate matter (PM2.5) and black carbon were measured over
two seasons at 23 sites. Annual mean (sd) was 34.1 (3.2)
mug/m(3) for PM2.5 and 2.7 (0.5) mug/m(3) for black carbon. The
LUR model for annual black carbon explained 78% of total
variance and included both local-scale (energy supply places)
and regional-scale (roads) predictors. Explained variance was
58% for annual PM2.5 and the included predictors were only
regional (urbanicity, vegetation). During leave-one-out
cross-validation and cross-holdout validation, only the black
carbon model showed consistent performance. The LUR model for
black carbon explained a substantial proportion of the spatial
variability that could not be captured by simpler interpolation
technique (ordinary kriging). This is the first study to develop
a LUR model for ambient concentrations of PM2.5 and black carbon
in a non-urban area of LMICs, supporting the applicability of
the LUR approach in such settings. Our results provide insights
on the added value of manually-collected built-environment data
to improve the performance of LUR models in settings with
limited data availability. For both pollutants, LUR models
predicted substantial within-village variability, an important
feature for future epidemiological studies
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