NEAR-INSTANTANEOUS IMPACTS OF HIGH PM EPISODES
ON CARDIOPULMONARY FUNCTION IN HEALTHY ADULTS
PROJECT NUMBER: EH-05-02
HENK MEUZELAAR, NEIL ARNOLD, CRISTINA JARAMILLO AND KERRY
KELLY, UNIVERSITY OF UTAH
GERARDO MEJIA, JORGE GARCIA, JESUS SANTOS, MARCO MARTINEZ,
MAXIMO SIERRA, AIDA ROJAS, ALEJANDRA ESTRADA AND NARDA
RICHAUD, INSTITUTO TECNOLOGICO Y DE ESTUDIOS SUPERIORES DE
MONTERREY
WEN-WHAI LI, JESSICA JAMEZ, NANCY GARCIA AND DONALD BACA,
UNIVERSITY OF TEXAS EL PASO
INTRODUCTION
Within the suburban and rural communities surrounding the sprawling Mexican
border cities of Mexicali, Reynosa and Juarez, research teams supported by the
Southwest Consortium for Environmental Research and Policy (SCERP) have
repeatedly observed severe, transient evening PM episodes, with PM10
concentrations ranging from 250 to well over 1,000 µg/m3 for periods of up to four
hours. Cumulative monitoring periods were analyzed totaling approximately
eight days for designated areas in the direct vicinity of Mexicali (December
1993), Reynosa (December 1995), and Juarez (January 1999). Three such perimetropolitan particulate matter (“{PM}2”) episodes were reported, thereby
indicating that high evening PM episodes are neither infrequent nor confined to a
single border location (Mejia-Velazquez et al. 1997) Figure 1 shows seasonallyaveraged, hourly PM2.5 levels for the Sunmetro (a.k.a. CAMS40) site operated by
the Texas Commission for Environmental Quality (TCEQ) near the border in El
Paso. Evening PM episodes occur every two to four days, peaking around nineten pm at five to ten times higher concentration levels than average daytime
levels, with average Fall/ Winter season evening peak levels exceeding
Summer/Spring levels by about 20%.
The majority of {PM}2 episodes recorded thus far reveal a common pattern of
near-windless, nocturnal conditions with falling ambient temperatures and low-tozero mixing (inversion layer) heights. In late Spring and Summer the huge
quantities of ambient PM produced by a bustling Mexican border metropolis
during the evening traffic peak generally have a chance to disperse before
pronounced atmospheric cooling and decreasing mixing layer heights produce
stagnant conditions. However, during late Fall and Winter the combination of
reduced solar heating and earlier sunsets starts producing stagnant conditions
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before the evening traffic peak is completely over. This causes trapping of a thin,
high density PM blanket close to the ground. In the course of the evening this
dense, low laying PM cloud tends to slowly move down the Rio Grande river
drainage as well as across adjacent suburban and rural areas driven by thermal
drainage flows and related hydrodynamic forces, as explained by Fernando et al
(2001), thereby apparently creating the observed {PM}2 events.
Presumably, the {PM}2 episodes observed in suburban and rural areas represent
only the tip of an iceberg as each of these events may be expected to
correspond to a parent episode of at least equally high PM levels inside the
metropolis. Additionally, there are likely to be episodes in which the PM cloud
remains entirely stagnant, thus not leading to marked PM increases outside the
perimeter. Because of a lack of time-resolved PM2.5 and PM10 monitoring data
for Cd. Juarez and other Mexican border metropoli none of these assumptions
can be readily verified. Due to their transient nature nocturnal {PM}2 events and
their hypothetical urban parent episodes tend to remain hidden in standard 24-hr
PM10 and PM2.5 measurement statistics.
This prompts the question to what extent are short-lasting severe PM episodes
likely to pose a substantial health threat, if any. As reviewed by Michaels and
Kleinman (2000), observations on the physiological effects of PM on the human
body, as well as on test animals, indicate that short term exposure to high PM
levels can be associated with a host of physiological and pathological responses
ranging from minor changes in cardiovascular or pulmonary performance to lifethreatening asthma attacks or allergic reactions and, therefore, should eventually
lead to a new one hour PM exposure standard. A recent report by Peters et al. in
the New England Journal of Medicine (2004) reveals a three times higher risk of
heart attack in the first hour after being exposed to heavy traffic. Although there
is as of yet insufficient data to affix the blame on urban PM exposure, the
circumstantial evidence for such a link appears to be quite strong.
Furthermore, in the Spring of 2002 the Principal Investigators carried out a
SCERP-sponsored double-blind study of transient evening PM effects on
cardiopulmonary function in five healthy young adults, as recorded at 30-minute
intervals at the TCEQ Sodar site directly adjacent to the US/Mexican border. As
detailed in a recent SCERP Monograph (Meuzelaar, et al), this study
demonstrated the presence of strong associations between changes in PM 2.5
and, to a lesser extent, PM10 levels, as well as readily measurable changes in
both Electrocardiography (ECG) patterns and spirometry profiles in subject A, a
25-year old male. Spirometry profile changes showed moderately decreased
pulmonary performance whereas ECG pattern changes indicated reduced Heart
Rate Variability. Of the remaining four subjects two appeared to show marginally
detectable effects and the other two showed no measurable effects. However,
only subject A and one of the marginal responders were monitored during a
strong transient PM event. The other subjects happened to be monitored during
relatively weak evening PM events.
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RESEARCH OBJECTIVES
 To measure temporally-resolved (10-15 min interval) ambient PM2.5 and
PM10 concentrations plus basic meteorology parameters for minimally four
weeks at a central location in Cd. Juarez. This task will be carried out by Dr.
Mejia’s team at the Instituto Tecnologica y de Estudios Superiores de
Monterrey (ITESM), in collaboration with Dr. Li's University of Texas El Paso
(UTEP) team.

To measure sequential (30-min interval) ECG as well spirometry profiles of
subjectively healthy volunteers at the same Cd. Juarez location during
minimally one medium-to-high evening PM episode and one matched
evening period with low-to-medium PM levels. Approximately 10 subjects
will be monitored while exposed to ambient PM inside a fully screened,
gazebo-style enclosure. This task will be carried out jointly by Dr. Santo
(ITESM), Dr. Meuzelaar, University of Utah (UofU), and their co-workers.

To correlate temporally-resolved PM2.5 and PM10 concentration data plus
meteorological parameters with the corresponding cardiopulmonary timeseries data by means of advanced multivariate analysis techniques.
RESEARCH METHODOLOGY/APPROACHES
Current knowledge of the relationship between PM episodes and human health
or fitness is primarily statistical in nature. There are disturbingly strong statistical
correlations between episodes of high PM levels and high mortality levels in
urban environments (Pope, et al 1992). Moreover, there are similar statistical
correlations between high PM episodes and the number of patient visits to
doctor’s offices and clinics (Vedal 1997). However, the precise mechanisms
involved, as well as the possible relationships between particle composition and
health effects, remain largely unknown. Until recently, the only emerging
consensus was that individuals with already compromised cardiopulmonary
systems were most readily affected. In 1998, however, Pope and co-workers
(Pope, et al 1999) found measurable changes in HRV in elderly Utahns which
correlated with ambient PM levels. This important observation, since then
confirmed by several other research groups (A&WMA 2000), opened the area of
statistically observable PM health effects up to systematic experimental
verification.
Compared to the above-referenced study by Pope et al (1999) in which
correlations were observed between daily HRV measurements in six elderly
people and regional ambient PM levels (as registered by outdoors monitoring
stations), the research approach here makes use of the transient, high intensity
character of the anticipated evening PM events. These are further analyzed by
their presumptive parent episodes, to examine for near-instantaneous effects on
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ECG and spirometry profiles, in up to 10 relatively healthy subjects while
monitoring their personal ambient PM2.5 and PM10 exposure, as well as the
chemical composition of the corresponding PM receptor samples. The limited
scope of the proposed SCERP project permits a look at health effects among a
small group of people in a highly specific environment and, therefore, should only
be considered as a logical first step. Depending upon the outcome of the
proposed project, future studies are likely to include elderly people and/or people
with compromised cardio-pulmonary systems.
A previous SCERP-sponsored study (Meuzelaar, et al) enabled the development
of a battery of special preprocessing, exploratory analysis, data fusion and
multivariate calibration techniques, which have already demonstrated the
feasibility of the proposed approach by revealing a strong correlation between
ECG plus spirometry time-series data and corresponding ambient PM data for
one of five relatively healthy subject in their twenties. Based upon these findings
at the TCEQ Sodar site in EL Paso, described in more detail in Chapter 7 of the
most recent SCERP monograph (Meuzelaar, et al) a three-phase methodological
approach is proposed:
Phase 1 - During the late Fall/early Winter of 2005/2006, hourly PM10 and PM2.5
levels plus standard meteorological parameters (wind vectors, ambient
temperature, atmospheric pressure, humidity and precipitation) will be measured
by means of Dustrak and/or TEOM at the selected Cd. Juarez site for a minimum
period of one month. As soon as the onset of a typical evening PM event is
detected (defined by PM2.5 levels above 50 ug/m3 plus PM10/PM2.5 ratios of
maximally 7.0 and wind speeds below 5 mph, in order to avoid windblown crustal
PM events) a filter sampling system will collect PM samples for a maximum of
two hours per filter or until a preset pressure differential is measured across the
filter. Collected filter samples will be shipped to the ICES laboratory at the
University of Utah for organic chemical characterization by thermal desorption
(TD) GC/MS as well as inorganic characterization by means of X-Ray
Fluorescence.
Phase 2 - During a subsequent two to three week period the ITESM team will
operate at the same site until several "genuine” evening PM events have been
recorded. On low-wind afternoons around 1700 hrs, pre-selected and trained
volunteer subjects will be asked to start recording ECG and spirometry profiles at
30-minute intervals while exposed to ambient PM levels inside a fully screened
gazebo-style enclosure. In order to maintain double-blind test standards neither
the subjects nor the local test operator or medical supervisor inside the enclosure
will be given access to actual PM or meteorology data. Moreover, special
lighting will prevent subjects and operator inside the enclosure from visually
gauging ambient particulate matter levels. Meanwhile, the subjects will be
encouraged to perform light physical tasks such as slow walking or bicycling
using stationary exercise equipment. The goal is to obtain a minimum total of 12
measurement points per six hour long test period in order to obtain statistically
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robust correlation coefficients between the various parameters. During
subsequent days an attempt will be made to record a carefully matched nonevent control period with the same subjects. Only noninvasive, minimally
intrusive, FDA-approved telemedical monitoring devices will be used under the
supervision of a locally accredited physician or medical technician.
Phase 3 - All cardiopulmonary response measurements, physicochemical PM
characterization data and meteorological parameters will be integrated and
correlated by the UofU team. This includes preparation of Fourier-transformed
ECG traces and moment-transformed spirometer profiles, followed by Principal
Component Analysis (PCA) based techniques such as orthogonal (e.g. Varimax
and Discriminant) or oblique (e.g. Vardia) factor rotations, as well as multivariate
calibration methods such as Principal Component Regression (PCR) and
Canonical Correlation Analysis (CCA). As illustrated in SCERP Monograph #12
(Meuzelaar, et al) the specific sequences of multivariate data manipulations
developed for the ECG, spirometry and PM concentration time-series, both alone
and in various combinations, have proven to be effective tools for preprocessing,
exploratory analysis, fusion and multivariate calibration of these particular sets of
time-series data. For a more comprehensive explanation and overview of the
various multivariate data analysis procedures used – which falls well outside the
space limitations of the present report – the reader is again referred to Chapter 7
of SCERP monograph #12 (Meuzelaar, et al).
PROBLEMS/ISSUES ENCOUNTERED
The March 2006 monitoring period was exceptionally cold, windy and devoid of
sizable PM evening peaks. The absence of detectable evening PM peaks
prohibited the collection of meaningful ambient PM samples for organic and/or
inorganic chemical speciation purposes. Moreover, due to the cold weather
conditions, test subjects could not be exposed and monitored throughout the
entire planned evening peak windows. Finally, some of the recorded data were
lost due to a hard drive crash on one of the two laptops used (seemingly
precipitated by the harsh ambient conditions).
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RESEARCH FINDINGS
While starting to set up for Phase 1 (PM monitoring) at the ITESM campus in
Juarez during the second half of January 2006 it became clear that both Dr. Li’s
(TEOM-type) PM2.5 and PM10 monitors would be needed on-site to distinguish
between re-aerosolized PM peaks (caused by the frequent wind gusts) and
typical evening PM peaks on the basis of differences in PM10/PM2.5 ratios.
Although it would in principle have been possible to use Dr. Mejia’s five-channel
Climet Optical Particle Counter (OPC) to calculate those ratios- after careful
calibration against the TEOM monitors, the logistical problems of setting all three
monitors up long enough in one and the same location (on either side of the
border) in January proved insurmountable.
Therefore, it was decided to use both TEOM monitors at the Juarez ITESM site
during the Phase 2 PM exposure tests. These tests started on Feb 7 with the
experimental set-up (see Figure 2) and the training/instruction of nearly a dozen
volunteer tests subjects (ITESM students) by ITESM staff and students (see
Figure 3), with on-site plus off-site assistance by UofU staff, whereas UTEP
students installed the TEOM monitors.
The first exposure tests were conducted on Feb 8 with four volunteer test
subjects and were continued whenever weather conditions permitted. This
produced additional measurements on Feb 9 (four test subjects), Feb 13 (four
test subjects), Feb 20 (five test subjects), Feb 21 (three test subjects), and Feb
22 (five test subjects).
Because of the exceptionally cold and windy weather, with temperatures
repeatedly plunging into the low 40s (not counting wind chill factors) during the
second half of the evening, the six-hour test window for obtaining half-hourly
ECG and spirometry measurements had to be set between 1600 and 2200 hours
rather than between 1700 and 2300 hrs, as originally planned. The PM data
recorded during these test periods are shown in Figures 4-9.
Between Feb 8 and 22, a total of 25 ECG (figure 10) and spirometer (Figure 11)
time-series were recorded on 11 “healthy” subjects. The protracted windy
conditions not only caused long test delays, e.g. between Feb 13 and Feb 20, but
effectively prevented the evolution of marked evening PM events. A serious
additional problem was encountered when one of the two laptop computers used
in the field experiment suffered a disk crash. Although all test data had been
backed up on a regular basis, it later turned out that the ECG monitor software
saves some key file directory information in a different location and that without
this information it is impossible to use the recorded ECG data. All in all, about 30
% of the recorded ECG profiles were affected.
Nearly three weeks after the various teams had started, the field experiments
had to be concluded because of budgetary restrictions and continued poor, or at
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best marginal, weather forecasts. The subsequent Phase 3 data integration and
analysis work by the UofU team (assisted by two ITESM team members who
visited for two weeks to help put the finishing touches on this phase of the work)
confirmed that the ECG and spirometry data obtained during this entire test
period were indeed inconclusive, with none of the participants showing
statistically significant correlations between ECG profiles and measured PM
levels. Since none of the evenings saw PM2.5 levels above 30 µg/m3
Meanwhile however, marked progress had been achieved with the continued
development and testing of advanced ECG monitoring and FFT signal
conversion techniques. The new method, called “ECGIII” and developed by Neil
Arnold (UofU) can be applied to the old (King of Hearts) ECG monitors used in
2002, as well as the new ECG@home devices (Figure 10) used in the current set
of experiments. It automatically detects and selects “n” cardiac cycles to
eliminate the potential bias introduced by the slightly subjective and much more
laborious manual selection method. When used with the 2002 data set the
observed correlations are stronger.
Moreover, application of the relatively new Positive Matrix Factorization (PMF)
method, developed by Hopke and associates (2000) to the FFT-data from 2002
test subject A was shown to provide a clearer view of the possible physical
mechanisms underlying the observed strong covariance between ECG,
spirometry and PM changes in the data than produced thus far by the PCA and
PCR-based approaches reported in SCERP monograph #12 (Meuzelaar, et al).
Figure 12 shows the important contribution of low-frequency FFT components
during high PM episodes, confirming the findings of HRV studies using simple
heart rate monitors (Vedal 1997, Pope 1999, Holquin, et al 2003), while also
revealing that at least two different PMF factors show strong higher frequency
effects that necessarily remain hidden in low bandwidth heart rate monitor
experiments but appear to be brought out by the much higher bandwidths of
ECG time-series data.
Last but not least, the feasibility of low-budget, collaborative, capacity-building
experiments involving students, staff and faculty from three different SCERP
partner institutions was successfully demonstrated under very trying
environmental conditions.
CONCLUSIONS
Due to a lack of marked PM events throughout the Feb ‘06 monitoring period the
new data are inconclusive regarding the presence of cardiopulmonary responses
in other young adults.
Meta-analysis of the 2002 data confirms the statistical and mechanistic
significance of the fast, reversible PM response in our ECG and spirometry
profiles of a 25-yr old test subject.
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Low-cost, home-ECG monitors can be modified for time-series ambient
monitoring, thus providing wide-band, multi-parameter data at the cost of a
simple heart-rate monitor.
Positive Matrix Factorization (PMF) of FFT-coverted ECG time-series is shown to
be a promising tool for exploring underlying components, trends and potential
mechanisms.
RECOMMENDATIONS FOR FURTHER RESEARCH
It is recommended that future PM exposure studies along the US-Mexico border
are conducted, but that they involve more highly vulnerable test subjects.
Researchers and analysts will need to keep in mind that strong cardiopulmonary
responses might be observed. In order to accelerate the understanding of PMrelated cardiopulmonary mortality and morbidity, the use of MDA-enhanced ECG
& spirometry is recommended over heart rate monitoring alone.
RESEARCH BENEFITS
The reported exceptional weather conditions during the field test period have
prevented the occurrence of strong enough evening PM events to enable
effective testing of possible heart (ECG) and lung (spirometry) responses among
the eleven “subjectively healthy” test subjects. Consequently, this study has been
unable to confirm the earlier finding of near-instantaneous ECG and spirometry
responses among one of five test subjects exposed to a characteristically high
evening PM event in the PdN airshed during a similar SCERP-funded study
carried out in 2002.
In spite of the inconclusive field test results, the present study has produced
important benefits for regional, transboundary or international research into the
health effects of ambient PM levels, namely development and application of:
highly informative field-test procedures for potential heart (ECG) and lung
(spirometry) responses using affordable home-medical monitoring devices;
efficient signal conditioning plus Fourier-transform-based pre-processing
techniques for ECG and spirometry data; and advanced multivariate analysis
methods such as Positive Matrix Factorization (PMF). Availability of these
improved research techniques will enable SCERP and non-SCERP researchers
alike to study near-instantaneous as well as long-term health effects of ambient
PM hereto inaccessible to systematic investigation.
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Perhaps most importantly, the work reported here has demonstrated the
feasibility of designing and carrying out complex, collaborative field projects in
which research teams from several university campuses on both sides of the
border completed their assigned measurement tasks, notwithstanding the
extremely challenging weather conditions. This has resulted in significant
capacity building for the participating, SCERP-sponsored US-Mexican border
institutions.
The results of this research project have been presented in the form of a talk and
a poster (Figure 12) at the December 12-13, 2006 SCERP Technical Meeting in
Tucson, Arizona.
ACKNOWLEDGMENTS
The expert advice of Joanne Lighty and Adel Sarofim, as well as the technical
support of Dana Overacker are gratefully acknowledged
This work was sponsored by the Southwest Consortium for Environmental
Research and Policy (SCERP) through a cooperative agreement with the U.S.
Environmental Protection Agency. SCERP can be contacted for further
information through www.scerp.org and scerp@mail.sdsu.edu.
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REFERENCES
A&WMA Conference on “PM2000: Particulate Matter and Health”, January 2000,
Charleston (SC), USA (multiple platform and poster presentations).
Chueinta, W., Hopke, P.K., Paatero, P.; “Investigation of Sources of Atmospheric
Aerosol Urban and Suburban Residential Areas in Thailand by Positive Matrix
Factorization”, Atmospheric Environ., 34, 3319 (2000).
Fernando, H.J.S., S.M. Lee, J. Anderson, M. Princevac, E. Pardyjak, and S.
Grossman-Clarke. 2001. “Urban Fluid Mechanics: Air Circulation and
Contaminant Dispersion in Cities.” Environmental Fluid Mechanics 1:107-164.
Holquin, F., M.M. Tellez-Rojo, M. Cortes, J. Chow, D. Mannino, I. Romieu, M.
Hernandez. “Exposure to Fine Particulate Matter PM2.5 and Heart Autonomic
Regulation in a Sample of Elderly Residents of Mexico City.” Proceedings of the
Sixth Workshop on Mexico City Air Quality, 19-23 January 2003. Mexico DF,
Mexico.
Mejia-Velazquez, G.M., R. Lopez-Franco and H.L.C. Meuzelaar
“Characterization and Dynamics of Air Pollutants in the SouthEastern Mexico-US
Border Area”, , Final Report on SCERP Project # AQ95-10, August 1997.
Meuzelaar, H.L.C., N.S. Arnold, B. Nookala, G. Mejía, P. Medina, J. Sánchez,
W.W. Li, J. Bang, J. Fernando, and S.-M. Lee. “Estimating PM Exposure Risks
and Evaluating Health Effects of Evening PM Peaks Using GIS-Referenced Data
Fusion Methods: Pilot Study,” SCERP Monograph #12 chapter 7, in press.
Michaels, R.A. and M.L. Kleinman, “Clinical, Epidemiological and Bioassay
Evidence that Brief Exposure to Aerosols at High Concentrations Documented in
Excursions Can Cause Morbidity and Mortality”, presented at A&WMA Special
Conference on PM2000: Particulate Matter and Health, January 2000,
Charleston (SC), USA.
Peters, A., S. von Klot, M. Heier, I. Trentinaglia, A. Hörmann, H.E. Wichmann, H.
Löwel. “Exposure to Traffic and the Onset of Myocardial Infarction,” NEJM
351:1721-1730, October 2004.
Pope, C.A. III, Schwartz J., Ransom M.R.; Daily Mortality and PM10 Pollution in
Utah Valley, Arch Environ Health, 47, 211 (1992).
Pope, C.A. III et al.; “Heart Rate Variability Associated with Particulate Air
Pollution,” Am. Heart J. 1999 (in press).
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Vedal, S.; Ambient Particles and Health; Lines that Divide, J. Air & Waste Manag.
Assoc., 47, 551 (1997).
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