Air Pollution and Heart Rate Variability Among the Elderly in Mexico City
Holguín, Fernando*†; Téllez-Rojo, Marta M.†; Hernández, Mauricio†; Cortez, Marlene†‡; Chow, Judith C.§; Watson, John G.§; Mannino, David¶; Romieu, Isabelle†
From the *Emory University School of Medicine, Atlanta, GA; †Instituto Nacional de Salud Publica, Cuernavaca, Mexico; ‡Hospital ABC, Mexico D.F., Mexico; §Desert Research Institute, Reno, NV; and the ¶Centers for Disease Control and Prevention, Atlanta, GA.
Editors’ note: An invited commentary on this article appears on page 312.
Submitted 15 May 2003; final version accepted 23 May 2003.
Financial Support for this study was provided by the Departamento del Distrito Federal, Mexico (CONSERVA), The National Commission for Science and Technology (CONACyT), Mexico, and the National Center for Environmental Health from the Centers for Disease Control and Prevention (CDC), Atlanta, GA.
Correspondence: Fernando Holguin, Emory University School of Medicine, Grady Memorial Hospital, Suite 2c007, 80 Jesse Hill Jr. Drive, Atlanta, GA 30335. E-mail: firstname.lastname@example.org.
Background: Suspended particles and ozone have been associated with varying degrees of cardiac autonomic dysfunction
Methods: In Mexico City, residents from a nursing home underwent heart rate variability analysis every other day for 3 months. Indoor and outdoor PM2.5 (particulate matter less than 2.5 mm in diameter) were measured daily at the nursing home. Levels of ozone and other atmospheric pollutants were obtained from a nearby automated monitoring station.
Results: Of the initial 42 screened participants, 34 (81%) were followed during the study period. The 24-hour average levels of indoor PM2.5 ranged from 15 to 67 μg/m3, and outdoor PM2.5 ranged from 9 to 87 μg/m3. Daily 1-hour maximum ozone levels ranged from 47 to 228 ppb. After adjusting for age and heart rate, we observed a strong decrease in the high frequency component of heart rate variability and the average 24-hour concentrations of PM2.5. Participants with hypertension had considerably larger reductions in their HF-HRV (high frequency–heart rate variability) component in relation to both ozone and PM2.5 exposure.
Conclusions: Our results suggest that ambient levels of PM2.5 and ozone can reduce the high-frequency component of heart rate variability in elderly subjects living in Mexico City and that subjects with underlying hypertension are particularly susceptible to this effect.
An association of increased cardiopulmonary morbidity and mortality with particulate matter (PM) pollution has been shown in epidemiologic studies from various countries.1 Suspended particle exposure is also associated with increased rates of hospital admissions and emergency room visits for respiratory and cardiovascular causes.2-4 However, the mechanisms responsible for the increased cardiovascular morbidity and mortality are poorly understood. Environmental exposure to suspended particles has been associated with an increase in mean heart rate and cardiac rhythm abnormalities independent of oxygenation levels in both animals and humans.5,6 The link between particulate matter pollution and cardiac conduction abnormalities has led to research focusing on changes in autonomic cardiac regulation assessed by heart rate variability.7-9,13 Recent studies suggest that PM levels are associated with a reduced heart rate variability, which in turn is known as an independent risk factor for cardiovascular mortality.10-12 However, these studies were conducted with a small number of participants over a limited period of time, and the effects of PM2.5 (particulate matter less than 2.5 μm in diameter) and other specific pollutants on heart rate variability was either not reported7,9,14 or reported only partially.8 In the Mexico City metropolitan area air pollutant levels (in particular, fine particulates and ozone) frequently exceed the Environmental Protection Agency standards.15 Therefore, to explore the autonomic cardiac response in relation to air pollutant exposure, we conducted a longitudinal study among elderly residents of a nursing home located in the northeast of the metropolitan area, an area frequently exposed to high levels of suspended particles and ozone.16
The population under study consisted of volunteers who were the permanent residents of a nursing home in the northeast area of the metropolitan area. We followed participants over a period of 3 months, from February 8 to April 30, 2000, obtaining daily local measures of fine particulate matter (PM2.5) and studies every alternate day of heart rate variability. We excluded current smokers, participants with pacemakers or underlying cardiac arrhythmias, and persons who were unable to sign a consent form or attend the study site located within the nursing home. The ethics committee of the Mexican National Institute of Public Health approved this protocol.
Daily 24-hour measurements of PM2.5 were determined by gravimetric analysis using Mini-Vol portable air samplers (version 4.2, Eugene, OR) with 47-mm Teflon filters (Pall Gelman, Vancouver, WA) and flows set at 4 L/min. Outdoor monitors were located on the roof of the nursing home, approximately 150 feet from the entrance and the closest road. Indoor monitors were placed in common living areas. We performed gravimetric analysis of Teflon filters at the air laboratory of the National Center for Environmental Research and Training (CENICA) in Mexico City.
Ambient levels of O3 (ozone), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO), as well as climatic variables, were obtained from an automated monitoring station (Tacuba) located 3 km (NE) upwind from the study site. All pollutant levels were measured by Thermoelectron devices (Franklin, MA) We determined NO2 by chemiluminescence (Thermoelectron 42 MCA), SO2 by an ultraviolet fluorescent analyzer (Thermoelectron 42 MCA), ozone by ultraviolet photometry (Thermoelectron 49 MCA), and ambient CO levels by infrared light absorption (Thermoelectron 48 MCA). Filter gravimetric analysis was performed under controlled climatic conditions at a room temperature of 22°C (±°) with a relative humidity of 40% (±5%); each filter was exposed for 24 hours before gravimetric analysis. Filter weights were obtained by a micrometric scale (Cahn C; Thermo Cahn, Madison, WI) under laminal flow.
Heart Rate Variability Analysis
Participants were scheduled to have a heart rate variability analysis every other day between 8:00 AM and 1:00 PM using an LPPac Q, Predictor 3.0 (Arrhythmia Research Technology, Houston, TX), which meets standards of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology.17,18 Before measuring heart rate variability, we had participants rest in a supine position for 5 minutes. Each recording lasted 5 minutes while the participants continued in the supine position. We identified a QRS template by an automated algorithm that identifies the waveform most representative of the patient’s dominant rhythm. This template was compared with subsequent R waves using a correlation coefficient of 0.75 as previously described in the study by Liao et al.7 We discarded any test having more than 15% of abnormal QRS processes. A total of 132 heart rate variability studies (12.8%) were excluded through the editing process. All patients had at least 1 study excluded with an average of 3.81-15 excluded per participant. We estimated the power spectral density using a Fast Fourier Transformation and a Hanning window with a smoothing weight of 10. Three frequencies were obtained from the power spectral density: a high-frequency component (HRV–HF; 0.15-0.40 Hz), a low-frequency component (HRV–LF 0.04-0.15 Hz), and a very-low-frequency component (HRV–VLF 0.033-0.04 Hz)19
All participants answered a questionnaire, which included demographic information, smoking habits, and a daily diary to record their hourly activities. We extracted the medical history, diagnosis of hypertension, and medication use from the participants’ medical files.
To analyze the effects of PM2.5 and other pollutants on the population average HRV, we transformed the response variables HRV–HF and HRV–LF (msec2) using a log10. We calculated estimates of total PM2.5 exposure based on the time activity patterns and PM2.5 microenvironmental concentrations (indoors and outdoors). Our index of personal exposure to PM2.5 was calculated using the following formula: (PM2.5 indoors × hours spent indoors/24) + (PM2.5 outdoors × hours spent outdoors/24).
We initially studied the association of PM2.5 and ozone with HRV–HF, HRV—LF, and HRV–LF/HF ratio using generalized estimating equations. These models are specially developed to account for autocorrelation and allow for the use of both fixed and time-dependent covariates.20 We adjusted models for potential confounding factors, including participants’ age and the average heart rate during each HRV measurement. Hypertension, sex, minimum temperature, and relative humidity did not confound the association between HRV and PM2.5 and were not included in the regression models. Given the fact that patients with hypertension are more likely to have deregulation of the autonomic nervous system and reduced heart rate variability,21 we stratified our analyses separately for subjects with and without hypertension. All analyses were conducted using air pollutant concentrations on the same day and with a 1-day lag for PM2.5, ozone, as well as SO2, NO2, and CO ambient concentrations; multipollutant models, including PM2.5 and ozone, were also examined. All statistical analyses were conducted using Stata 6.0 (College Station, TX).
Of the initial 42 screened participants, 34 (81%) were followed up during the study period. The mean age was 79 years, and 44% were men. Thirteen participants had a diagnosis of hypertension (38%) and 6 had diabetes mellitus, other diagnoses included 4 patients with chronic bronchitis, 4 patients with Parkinson’s disease and 1 each with transient ischemic attacks, hypertension and ischemic cardiomyopathy. Participants spent 86% of the time indoors during the study period as determined by the results of an activity questionnaire completed daily. The mean number of hours spent indoors for the whole group was 21 hours (range: 12–24) and hours spent outdoors were 0.6 hours (0-6) while at the nursing home. The rate of reexamination was high, with a mean of 18 studies per participant and a total of 595 monitoring sessions. Subjects with a medical diagnosis of hypertension were more likely to be women and to spend more time indoors. The mean heart rate variability indices, averaged over the 3-month follow up, were higher for subjects without hypertension than for those with hypertension (Table 1).
Results from the air pollutants measured during the study are shown in Table 2. The 24-hour NAAQS (National Ambient Air Quality Standards) for PM2.5 were exceeded on 6 days, and the average indoor and outdoor levels where higher than previously reported in similar heart rate variability studies.7-9 Levels of ozone were also high during the study period, with more than 75% of days being above the NAAQS for the ozone 1-hour maximum. There was a moderate correlation (r = 0.52) between PM2.5 indoors and PM2.5 outdoors, and the correlations of PM2.5 estimates of total exposure with PM2.5 indoors and PM2.5 outdoors were r = 0.92 and r = 0.55, respectively. The correlation of the ozone one-hour maximum with PM2.5 indoors, PM2.5 outdoors, and PM2.5 total exposure were r = 0.27, r = 0.47 and r = 0.18, respectively.
Measurements of Heart Rate Variability
The observed associations between the daily variation of PM2.5 total exposure and the HRV indices are presented in Table 3. After adjusting for age, heart rate, and hypertension, we observed an inverse relation between the high-frequency component of heart rate variability and total PM2.5. A 10-μg/m3 increase in PM2.5 was associated with a 5.0% change in HRV–HF. The exposure to indoor levels of PM2.5 was associated with a substantial reduction in the HRV–HF component (β = −0.049; confidence interval = −0.090–0.007 for a 10-μg/m3 increase in PM2.5) and exposure to outdoor PM2.5 was associated with a more modest reduction in high frequency (β = −0.023; −0.058-0.010 for a 10-μg/m3 increase in PM2.5). When restricting the analysis to participants who had a diagnosis of hypertension, a larger reduction in the HRV–HF component was observed, corresponding to a 7.1% change in HRV–HF for a 10-μg/m3 increase in PM2.5. We used associations with other metric parameters of heart rate variability to assess the impact of air pollutants on cardiac autonomic dysfunction; low frequency (HRV–LF) showed a moderate inverse association with PM2.5, whereas the LH/FH ratio showed a modest positive association with levels of PM2.5. In addition, changes in heart rate variability were strongly related to ambient ozone concentrations among subjects with hypertension for HRV–HF and HRV–LF (Table 4), corresponding to a 2.0% change in heart rate variability per 10 ppb increase in ozone 1-hour maximum. Control for diabetes did not change the observed associations. Of our patients with hypertension, 8 were taking angiotensin-converting enzyme inhibitors, 2 were taking beta-blockers, 4 were taking a calcium channel blocker, and 2 were taking a thiazide diuretic. Because of the small number of participants, we were unable to stratify the effect of PM2.5 on HRV by each group of antihypertensive medications.
Other pollutants (NO2, CO, and SO2) were not related to heart rate variability (Table 5). All of these results are for air pollution parameter on the same day as the heart rate variability assessments; results were similar when we used 1-day time-lag exposure for the pollutants.
In multipollutant models, including both PM2.5 and ozone, the magnitude of the relation of PM2.5 with the HRV–HF component decreased slightly (Table 6), corresponding to the following percent changes: 5.0% in our total sample, 4.0% among participants without hypertension, and 6.4% among participants with hypertension for a 10-μg/m3 increase in PM2.5. Ozone was no longer associated with HRV–HF (Table 6).
This is one of the largest studies to date on the effects of PM2.5 and ozone on heart rate variability, and it is the first of its kind in Mexico. Our results suggest that exposure to ambient air concentrations of PM2.5 and ozone is associated with autonomic cardiac dysfunction in the elderly, characterized by a reduction in the high frequency or vagal component of heart rate variability. Furthermore, in our study, participants with a diagnosis of hypertension appeared to be more susceptible with larger reductions in the HRV–HF associated with PM2.5 exposure. Although individuals diagnosed with hypertension are known to have lower heart rate variability,21 an increased susceptibility to particulate air pollution in this group of patients has not been previously described. In our study, exposure to ambient levels of ozone was also associated with reductions in the HRV–HF component, although this effect was not as strong in the multipollutant models that adjusted for PM2.5.
Numerous mechanistic hypotheses have been proposed to explain how exposure to ambient levels of PM2.5 might produce changes in the autonomic cardiac regulation. Translocation of inhaled ultrafine particles into the systemic circulation,22 the activation of pulmonary irritant receptors that mediate the stimulation of parasympathetic pathways,23 an increase in plasma viscosity,24 and the elevation of inflammatory mediators25 are some of the potential biologic explanations. It is possible that the stimulation of irritant receptors from ozone-induced airway inflammation and oxidation23 can either independently lead to changes in heart rate variability or potentiate the effect of inhaled particulates. In general, it is conjectured that interactions among inflammation, abnormal hemostatic function, and altered cardiac rhythm might play an important role in the pathogenesis of cardiopulmonary diseases related to air pollution.26
Several limitations have to be considered in interpreting our results. We used only short-term heart rate variability recordings (5 min), which could have hindered the possibility of performing an adequate assessment of lower frequencies. However, there is a high correlation between short recordings of HRV–HF using spectral analysis and using longer time-domain analysis.27 Because we obtained short-term study results that were performed during the morning, we were unable to account for any changes related to circadian variation in heart rate variability parameters. Maneuvers to elicit vagal responses, such as metronomic breathing, were not performed, but controlling respiratory rate does not seem to confound the association between PM2.5 and changes in heart rate variability.8 The same trained technician performed the entire heart rate variability recording, thus reducing intertest variability. PM2.5 exposure was limited to 384 observations from 34 subjects who had complete time activity data; these coefficients were not substantially different from coefficients calculated from the 595 heart rate variability monitoring sessions using PM2.5 indoor exposure.
Restricting analysis to outdoor PM2.5 was associated with a modest reduction in the HRV–HF component, suggesting that some indoor sources might play a role. We were unable to identify significant indoor exposure sources and the nursing home was a smoke-free environment. However, idling diesel buses were parked for a few hours close to the nursing home indoor living areas at least 3 times a week. We speculate that such emissions could have contributed to the larger effects seen in association with indoor PM2.5.
Information about ozone concentration and other pollutants was available through a nearby automated monitoring station, which was situated 3 km upwind from the study site, allowing a reasonable estimation of the nursing home ozone air pollution. Measurements for NO2 and CO are more susceptible to local sources of emission and traffic flow, and therefore might not be representative of the nursing home environment. Our results are from a single nursing home located in the northeast metropolitan area and might not be applicable to a more general population; still our findings are consistent with a similar study of elderly nursing home residents.7 A reduction in heart rate variability has been positively correlated with increased rates of cardiovascular morbidity and mortality in both the high-risk and the general population.11,12 However, further studies are needed to determine whether the daily fluctuations in autonomic cardiac balance associated with exposure to ambient particulate matter and ozone will provide meaningful clinical and epidemiologic data. Results from this study complement previous reports by identifying subjects with hypertension as a population potentially at risk of experiencing the adverse cardiovascular health effects associated with ambient ozone and particulate air pollution.
We thank the CENICA (Centro Nacional de Investigación y Capacitación Ambientales in Mexico City) group and Victor Gutierrez for their contribution in performing the gravimetric analyses in our study; the DIF (Departamento de Integración Familiar, México) for allowing them to perform the study in their nursing home, and Isabel García and Rafael Santibañnez for their technical support.
1.Schwartz J. Air pollution and daily mortality: a review and meta analysis. Environ Res
2.Burnett RT, Smith-Doiron M, Stieb D, et al. Effects of particulate matter and gaseous pollution on cardiorespiratory hospitalizations. Arch Environ Health
3.Wordley J, Walters S, Ayres JG. Short term variations in hospital admissions and mortality and particulate pollution. Occup Environ Med
4.Tolbert P, Klein M, Metzger KB, et al. Interim results of the study of particulates and health in Atlanta (SOPHIA). Journal of Exposure and Environmental Epidemiology
5.Pope CAI, Dockery DW, Kanner RE, et al. Oxygen saturation, pulse rate, and particulate air pollution: a daily time-series panel study. Am J Respir Crit Care Med
6.Godleski JJ, Verrier RL, Koutrakis P, et al. Mechanisms of morbidity and mortality from exposure to ambient air particles. Health Effects Institute Research Reports, 2000. Available at: http://www.healtheffects.org/Pubs/Godleski.pdf
7.Liao D, Creason J, Shy C, et al. Daily variation of particulate air pollution and poor cardiac autonomic control in the elderly. Environ Health Perspect
8.Gold DR, Litonjua A, Schwartz J, et al. Ambient pollution and heart rate variability. Circulation
9.Pope CAI, Verrier RL, Lovett EG, et al. Heart rate variability associated with particulate air pollution. Am Heart J
10.Tsuji H, Venditti FJ, Manders ES, et al. Reduced heart rate variability and mortality risk in an elderly cohort. Circulation
11.Dekker JM, Schouten EG, Klootwijk P, et al. Heart rate variability from short electrocardiographic recordings predicts mortality from all causes in middle-aged and elderly men. Am J Epidemiol
12.Tsuji H, Larson MG, Venditti FJ, et al. Impact of reduced heart rate variability on risk for cardiac events. Circulation
13.Magari SR, Schwartz J, Paige L, et al. The associations between personal measurements of environmental exposure to particulates and heart rate variability. Epidemiology
14.Magari RS, Hauser R, Schwartz J, et al. Association of heart rate variability with occupational and environmental exposure to particulate air pollution. Circulation
15.Borja-Aburto VH, Castillejos M, Gold DR, et al. Mortality and ambient fine particles in southwest Mexico City. Environ Health Perspect
16.Carabias LJ, Provencio ED, Fernández AB, et al. Almanaque de datos y tendencias de la calidad del aire en ciudades Mexicanas.
Dirección general de gestión e Información Ambiental del instituto Nacional de Ecología. CENICA; 2000.
17.The Task Force of The European and the North American Society of Pacing and Electrophysiology. Heart rate variability: standards of measurement, physiological interpretation, and clinical use. Circulation.
18.Kennedy HL. Heart rate variability instruments from commercial manufacturers. In: Malik M, Camm AJ, eds. Heart Rate Variability.
Armonk, NY: Futura Publishing; 1st ed. 1995:127–132.
19.Stein PK, Bosner MS, Kleiger RE, et al. Heart rate variability: a measure of cardiac autonomic tone. Am Heart J
20.Diggle PJ, Liang KY, Zeger SL. Analysis of Longitudinal Data
. New York: Oxford University Press; 2001.
21.Singh JP, Larson MG, Tsuji H, et al. Reduced heart rate variability and new-onset hypertension: insights in to the pathogenesis of hypertension: the Framingham Heart Study. Hypertension
22.Nemmar A, Hoet PHM, Vanquickenborne B, et al. Passage of inhaled particles into the blood circulation in humans. Circulation
23.Watkinson WP, Campen CJ, Nolan JP, et al. Cardiovascular and systemic responses to inhaled pollutants in rodents: effects of ozone and particulate matter. Environ Health Perspect
. 2001;109(suppl 4):539–546.
24.Koening WSMLH, Döring A, Ernst E. Association between plasma viscosity and all-cause mortality: results from the MONICA-Ausburg cohort study. Br J Haematol
25.Schwartz J. Air pollution and blood markers of cardiovascular risk. Environ Health Perspect
. 2001;109(suppl 3):405–409.
26.Arden Pope C III. Epidemiology of fine particulate air pollution and human health: biologic mechanisms and who’s at risk? Environ Health Perspect.
27.Sinnreich RK, Friedlander Y, Sapoznikov D, et al. Five minute recordings of heart rate variability for population studies: repeatability and age-sex characteristics. Heart
A Stein is a Stein is a Stein?
Readers of our July issue may wonder how Epidemiology could have mistaken a physician who left her home country to become a renowned epidemiologist, for a physician who left her home country to become a renowned poet.
We’re wondering too.
Figure. Gertrude Ste...Image Tools
This article has been cited 70 time(s).
Environmental HealthTraffic-related air pollution exposures and changes in heart rate variability in Mexico City: A panel studyEnvironmental Health
Journal of Epidemiology and Community HealthEpidemiological evidence on association between ambient air pollution and stroke mortalityJournal of Epidemiology and Community Health
Journal of the Air & Waste Management Association
Health effects of fine particulate air pollution: Lines that connect
Journal of the Air & Waste Management Association, 56(6):
Occupational and Environmental MedicineAssociation of ventricular arrhythmias detected by implantable cardioverter defibrillator and ambient air pollutants in the St Louis, Missouri metropolitan areaOccupational and Environmental Medicine
Journal of Toxicology and Environmental Health-Part A-Current IssuesAir Pollution and Emergency Room Visits for Arrhythmias: Are There Potentially Sensitive Groups?Journal of Toxicology and Environmental Health-Part A-Current Issues
Inhalation ToxicologyTotal lung deposition of ultrafine particles in elderly subjects during controlled breathingInhalation Toxicology
Journal of Occupational and Environmental MedicineAssociations between submicrometer particles exposures and blood pressure and heart rate in patients with lung function impairmentsJournal of Occupational and Environmental Medicine
Salud Publica De Mexico
Use of heartrate variability as a marker of cardiovascular effects associated with air pollution
Salud Publica De Mexico, 48(4):
European Heart JournalEffects of air pollution on blood pressure and heart rate variability: a panel study of vehicular traffic controllers in the city of Sao Paulo, BrazilEuropean Heart Journal
Journal of Epidemiology and Community HealthIncreased resting heart rate with pollutants in a population based studyJournal of Epidemiology and Community Health
American Journal of Respiratory and Critical Care MedicineOmega-3 fatty acid prevents heart rate variability reductions associated with particulate matterAmerican Journal of Respiratory and Critical Care Medicine
Environmental Health PerspectivesThe effect of supplementation with omega-3 polyunsaturated fatty acids on markers of oxidative stress in elderly exposed to PM2.5Environmental Health Perspectives
Cardiac autonomic changes associated with fish oil vs soy oil supplementation in the elderly
Respiratory ResearchDoes respiratory health contribute to the effects of long-term air pollution exposure on cardiovascular mortality?Respiratory Research
American Journal of EpidemiologyAmbient air pollution and cardiovascular emergency department visits in potentially sensitive groupsAmerican Journal of Epidemiology
Critical Reviews in ToxicologyShort-term effects of particulate matter: An inflammatory mechanism?Critical Reviews in Toxicology
Environmental ResearchMaternal exposure to ambient air pollutants and risk of congenital anomaliesEnvironmental Research
International Journal of Hygiene and Environmental HealthEffects of nitrogen dioxide on human health: Systematic review of experimental and epidemiological studies conducted between 2002 and 2006International Journal of Hygiene and Environmental Health
Environmental Health PerspectivesAssociation of Heart Rate Variability in Taxi Drivers with Marked Changes in Particulate Air Pollution in Beijing in 2008Environmental Health Perspectives
Environmental Health PerspectivesReduction in Heart Rate Variability with Traffic and Air Pollution in Patients with Coronary Artery DiseaseEnvironmental Health Perspectives
Environmental Health PerspectivesEffects of particle size fractions on reducing heart rate variability in cardiac and hypertensive patientsEnvironmental Health Perspectives
Journal of Exposure Science and Environmental EpidemiologyRelationship between indoor, outdoor, and personal fine particle concentrations for individuals with COPD and predictors of indoor-outdoor ratio in Mexico cityJournal of Exposure Science and Environmental Epidemiology
American Journal of Respiratory and Critical Care MedicineA case-crossover analysis of out-of-hospital coronary deaths and air pollution in Rome, ItalyAmerican Journal of Respiratory and Critical Care Medicine
Journal of Allergy and Clinical ImmunologyImmigration to the United States and acculturation as risk factors for asthma and allergyJournal of Allergy and Clinical Immunology
Journal of Exposure Science and Environmental EpidemiologyEffects of ultrafine and fine particulate and gaseous air pollution on cardiac autonomic control in subjects with coronary artery disease: The ULTRA studyJournal of Exposure Science and Environmental Epidemiology
Environmental Health PerspectivesCoarse particulate matter (PM2.5-10) affects heart rate variability, blood lipids, and circulating eosinophils in adults with asthmaEnvironmental Health Perspectives
Cardiovascular ToxicologyHeart rate variability in rodents: uses and caveats in toxicological studiesCardiovascular Toxicology
Journal of Occupational and Environmental MedicineAmbient carbon monoxide may influence heart rate variability in subjects with coronary artery diseaseJournal of Occupational and Environmental Medicine
Environmental Health PerspectivesEffects of air pollution on heart rate variability: The VA Normative Aging StudyEnvironmental Health Perspectives
ThoraxAssociation between short term exposure to fine particulate matter and heart rate variability in older subjects with and without heart diseaseThorax
Environmental Health PerspectivesObesity is a modifier of autonomic cardiac responses to fine metal particulatesEnvironmental Health Perspectives
Environmental Health PerspectivesAssociations between PM2.5 and Heart Rate Variability Are Modified by Particle Composition and Beta-Blocker Use in Patients with Coronary Heart DiseaseEnvironmental Health Perspectives
Journal of Exposure Science and Environmental EpidemiologyPersonal PM2.5 and CO exposures and heart rate variability in subjects with known ischemic heart disease in Mexico CityJournal of Exposure Science and Environmental Epidemiology
Journal of Cardiovascular Pharmacology and TherapeuticsDirect and acute cardiotoxic effects of ultrafine air pollutants in spontaneously hypertensive rats and Wistar-Kyoto ratsJournal of Cardiovascular Pharmacology and Therapeutics
European Heart JournalIndividual exposure to particulate matter and the short-term arrhythmic and autonomic profiles in patients with myocardial infarctionEuropean Heart Journal
Journal of Aerosol Medicine-Deposition Clearance and Effects in the Lung
Cardiovascular effects of fine and ultrafine particles
Journal of Aerosol Medicine-Deposition Clearance and Effects in the Lung, 18(1):
Inhalation ToxicologyEffects of subchronic exposures to concentrated ambient particles (CAPs) in mice: I. Introduction, objectives, and experimental planInhalation Toxicology
Environmental Health PerspectivesPotential role of ultrafine particles in associations between airborne particle mass and cardiovascular healthEnvironmental Health Perspectives
Clinical Reviews in Allergy & Immunology
Airborne environmental injuries and human health
Clinical Reviews in Allergy & Immunology, 31(1):
American Journal of Industrial MedicineSocioeconomic status, particulate air pollution, and daily mortality: Differential exposure or differential susceptibilityAmerican Journal of Industrial Medicine
Occupational and Environmental MedicineA panel study in congestive heart failure to estimate the short-term effects from personal factors and environmental conditions on oxygen saturation and pulse rateOccupational and Environmental Medicine
Environmental ResearchThe avoidable health effects of air pollution in three Latin American cities: Santiago, Sao Paulo, and Mexico CityEnvironmental Research
Journal of Epidemiology and Community HealthAir pollution and cardiovascular admissions association in Spain: results within the EMECAS projectJournal of Epidemiology and Community Health
Environmental Health PerspectivesCoarse particles and heart rate variability among older adults with coronary artery disease in the Coachella Valley, CaliforniaEnvironmental Health Perspectives
Environmental Health PerspectivesParticulate air pollution, oxidative stress genes, and heart rate variability in an elderly cohortEnvironmental Health Perspectives
Environmental Health PerspectivesMetabolic syndrome and inflammatory responses to long-term particulate air pollutantsEnvironmental Health Perspectives
Environmental ResearchAir pollution and hospital admissions for congestive heart failure: Are there potentially sensitive groups?Environmental Research
CirculationParticulate Matter Air Pollution and Cardiovascular Disease An Update to the Scientific Statement From the American Heart AssociationCirculation
Occupational and Environmental MedicineA panel study of air pollution in subjects with heart failure: negative results in treated patientsOccupational and Environmental Medicine
Biochimica Et Biophysica Acta-General SubjectsPM-induced cardiac oxidative stress and dysfunction are mediated by autonomic stimulationBiochimica Et Biophysica Acta-General Subjects
Environmental Health PerspectivesDifferences in heart rate variability associated with long-term exposure to NO2Environmental Health Perspectives
American Journal of EpidemiologyVascular Function, Inflammation, and Variations in Cardiac Autonomic Responses to Particulate Matter Among WeldersAmerican Journal of Epidemiology
European Respiratory JournalAir pollution, oxidative stress and dietary supplementation: a reviewEuropean Respiratory Journal
Inhalation ToxicologyAmbient air pollution alters heart rate regulation in aged miceInhalation Toxicology
Revista Medica De Chile
Atmospheric pollution and cardiovascular damage
Revista Medica De Chile, 132(6):
ThoraxThe way to dusty death?Thorax
Respiratory ResearchTraffic-related air pollution and respiratory symptoms among asthmatic children, resident in Mexico City: the EVA cohort studyRespiratory Research
Biomedical and Environmental SciencesRelationship between Ambient Fine Particles and Ventricular Repolarization Changes and Heart Rate Variability of Elderly People with Heart Disease in Beijing, ChinaBiomedical and Environmental Sciences
Urban Environmental Pollution 2010Medical consultation in productive age population related with air pollution levels in Bogota cityUrban Environmental Pollution 2010
Environmental Monitoring and AssessmentSeasonal variation in the acute effects of ozone on premature mortality among elderly JapaneseEnvironmental Monitoring and Assessment
European Journal of Cardiovascular Prevention & RehabilitationAssociation between nitrogen dioxide and heart rate variability in a susceptible populationEuropean Journal of Cardiovascular Prevention & Rehabilitation
EpidemiologyTraffic-Generated Air Pollution and Myocardial InfarctionEpidemiology
Journal of Occupational and Environmental MedicineShort-Term Effects of Air Pollution on Heart Rate Variability in Senior Adults in Steubenville, OhioJournal of Occupational and Environmental Medicine
Journal of Occupational and Environmental MedicinePersonal Coronary Risk Profiles Modify Autonomic Nervous System Responses to Air PollutionJournal of Occupational and Environmental Medicine
Journal of Occupational and Environmental MedicineControlled Exposure to Combined Particles and Ozone Decreases Heart Rate VariabilityJournal of Occupational and Environmental Medicine
particulate air pollution; ozone; heart rate variability; Mexico; elderly
© 2003 Lippincott Williams & Wilkins, Inc.
Highlight selected keywords in the article text.