Environmental Health Perspectives • volume 117 | number 7 | July 2009 1089

Research

The U.S. Environmental Protection Agency 

(EPA) currently regulates particulate matter 

(PM) on the basis of mass in two size ranges: 

coarse PM [2.5–10 μm in aerodynamic 

diameter (PM2.5-10)] and fine PM (PM2.5). 

Coarse PM typically derives from soil or abrasive mechanical processes in transportation 

or industry, and also can contain biogenic 

materials such as pollen, endotoxin, and 

mold spores known to have deleterious effects 

on human health, especially in those with 

pulmonary diseases such as asthma. In the 

western United States, coarse PM typically 

comprises > 50% of measured PM10 mass 

on an annual basis, and approaches 70% in 

some areas of the Southwest. Fine PM derives

primarily from combustion processes and 

may contain both primary particles directly 

emitted from specific sources and secondary 

particles formed by atmospheric chemistry 

changes over time. Wilson and Suh (1997) 

provide a detailed description of the occurrence and composition of coarse and fine PM 

and conclude that they are separate classes of 

pollutants and should be measured separately 

in epidemiology and toxicology studies.

In addition to difference in chemical 

composition, these two size fractions deposit 

in different locations in the lung, with coarse 

PM predominantly depositing in the more 

proximal portion of the lung (Kim and Hu 

1998). Because lung deposition and chemical composition of fine and coarse PM are 

generally dissimilar, PM may produce biologic activity and health effects distinct in 

nature and severity from those effects seen 

with exposure to fine PM.

Epidemiology studies using time-series 

analyses have demonstrated significant correlations between exposure to ambient PM 

air pollution and increased mortality and 

morbidity. Although most time-series studies 

have demonstrated health effects to be more 

strongly correlated with the PM2.5 fraction

than with the PM2.5–10 fraction (Cifuentes 

et al. 2000; Klemm et al. 2000; Lipfert et al. 

2000; Schwartz and Neas 2000), there is 

some evidence for effects of coarse PM on 

mortality and morbidity, especially in arid 

regions where coarse PM concentrations are 

relatively high (Castillejos et al. 2000; Mar 

et al. 2000; Ostro et al. 2000). Epidemiologic 

evidence of health effects associated with 

coarse PM was recently reviewed (Brunekreef 

and Forsberg 2005).

A panel study of 19 nonsmoking older 

adults with cardiovascular disease residing in 

the Coachella Valley, California, reported an 

association between decreased heart rate variability (HRV) and coarse PM (Lipsett et al. 

2006). A panel study of 12 adult asthmatics residing in Chapel Hill, North Carolina, 

reported associations between HRV, blood 

lipids, and circulating eosinophils and coarse, 

but not fine, PM (Yeatts et al. 2007).

Recently, virtual impactor technology 

(Demokritou et al. 2002; Kim et al. 2000) 

has been used to expose humans to concentrated fine ambient PM. These studies have 

reported that fine concentrated ambient 

particles (CAPs) can cause mild pulmonary 

inflammation and increased blood fibrinogen in healthy volunteers (Ghio et al. 2000,

2003), decreased HRV in healthy elderly volunteers (Devlin et al. 2002), decreased arterial 

oxygenation and HRV in elderly volunteers 

who are healthy but have chronic obstructive pulmonary disease (Gong et al. 2004a), 

and increased HRV and mediators of blood 

coagulation in healthy and asthmatic subjects (Gong et al. 2003a). Additionally, exposure of healthy volunteers to fine CAPs plus 

ozone caused brachial artery vasoconstriction 

(Brook et al. 2002) and increased diastolic 

blood pressure (Urch et al. 2005), and these 

findings were attributed primarily to CAP

constituents (Urch et al. 2004).

To understand more fully the pathologic 

effects of the coarse fraction and to determine 

biological plausibility of epidemiologic studies, we examined the physiologic effects of 

concentrated Chapel Hill coarse CAPs on several cardiac, blood, and pulmonary end points 

Address correspondence to R. Devlin, Human 

Studies Division, MD 58D, NHEERL, U.S. 

Environmental Protection Agency, Research Triangle 

Park, NC 27711 USA. Telephone: (919) 966-6255. 

Fax: (919) 966-6271. E-mail: Devlin.robert@epa.gov

We thank M. Bassett, J. Carter, L. Dailey, 

S. Harder, M. Herbst, D. Levin, T. Montilla, R. 

Silbajoris, J. Soukup, M. Case, and J. Stonehuerner 

for their invaluable technical and medical assistance 

in the execution of this study. 

The research described in this article has been 

reviewed by the National Health and Environmental 

Effects Research Laboratory, U.S. Environmental 

Protection Agency, and approved for publication. 

Approval does not signify that the contents necessarily reflect the views and the policies of the agency, nor 

does mention of trade names or commercial products 

constitute endorsement or recommendation for use.

The authors declare they have no competing 

financial interests.

Received 9 January 2009; accepted 23 March 2009.

Exposure to Concentrated Coarse Air Pollution Particles Causes 

Mild Cardiopulmonary Effects in Healthy Young Adults

Donald W. Graff,1 Wayne E. Cascio,2 Ana Rappold,3 Haibo Zhou,4 Yuh-Chin T. Huang,5 and Robert B. Devlin3

1MDS Pharma Services, Lincoln, Nebraska, USA; 2Department of Cardiovascular Sciences, East Carolina University Brody School of 

Medicine, Greenville, North Carolina, USA; 3Human Studies Division, National Health and Environmental Effects Research Laboratory, 

U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA; 4School of Public Health, University of North 

Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; 5School of Medicine, Duke University, Durham, North Carolina, USA

Background: There is ample epidemiologic and toxicologic evidence that exposure to fine particulate 

matter (PM) air pollution [aerodynamic diameter ≤ 2.5 μm (PM2.5)], which derives primarily from 

combustion processes, can result in increased mortality and morbidity. There is less certainty as to 

the contribution of coarse PM (PM2.5–10), which derives from crustal materials and from mechanical 

processes, to mortality and morbidity. 

Objective: To determine whether coarse PM causes cardiopulmonary effects, we exposed 

14 healthy young volunteers to coarse concentrated ambient particles (CAPs) and filtered air. 

Coarse PM concentration averaged 89.0 μg/m3 (range, 23.7–159.6 μg/m3). Volunteers were 

exposed to coarse CAPs and filtered air for 2 hr while they underwent intermittent exercise in a 

single-blind, crossover study. We measured pulmonary, cardiac, and hematologic end points before 

exposure, immediately after exposure, and again 20 hr after exposure. 

Results: Compared with filtered air exposure, coarse CAP exposure produced a small increase in 

polymorphonuclear neutrophils in the bronchoalveolar lavage fluid 20 hr postexposure, indicating 

mild pulmonary inflammation. We observed no changes in pulmonary function. Blood tissue plasminogen activator, which is involved in fibrinolysis, was decreased 20 hr after exposure. The standard deviation of normal-to-normal intervals (SDNN), a measure of overall heart rate variability,

also decreased 20 hr after exposure to CAPs. 

Conclusions: Coarse CAP exposure produces a mild physiologic response in healthy young volunteers approximately 20 hr postexposure. These changes are similar in scope and magnitude to 

changes we and others have previously reported for volunteers exposed to fine CAPs, suggesting that 

both size fractions are comparable at inducing cardiopulmonary changes in acute exposure settings.

Key words: cardiovascular effects, coarse PM human study. Environ Health Perspect 117:1089–1094 

(2009). doi:10.1289/ehp0900558 available via http://dx.doi.org/ [Online 23 March 2009]
Graff et al.

1090 volume 117 | number 7 | July 2009 • Environmental Health Perspectives

in young, healthy volunteers. This study is 

part of a continuing series of studies in which 

humans are exposed to different size fractions 

of Chapel Hill PM and will also allow us to 

compare the relative toxicity of coarse and 

fine PM from the same geographic location. 

We presented a brief comparison of humans 

exposed to three size fractions of Chapel Hill 

CAPs in condensed form in a symposium 

proceedings (Samet et al. 2007).

Materials and Methods

Study population. This was a single-blind, 

crossover study approved by the Committee 

on the Protection of the Rights of Human 

Subjects of the University of North Carolina at 

Chapel Hill School of Medicine. Before inclusion, participants were informed of the study 

procedures and risks, signed a statement of 

informed consent and were approved for participation by a U.S. EPA physician. Screening 

procedures included medical history, physical 

exam, and routine hematologic and biochemical tests. Specific exclusion criteria included any 

chronic medical condition or chronic medication use (except birth control pills, low-dose 

antibiotics for acne, or dietary supplements), 

significant risk factors for cardiovascular disease 

(e.g., high cholesterol or uncontrolled blood 

pressure), and current smokers or those with 

a significant smoking history within 1 year of 

study participation. Subjects suffering from 

seasonal allergies were not studied within 6 

weeks of a symptomatic episode, and no subject was studied within 4 weeks of a respiratory 

tract infection. Individuals unable to discontinue substances that could potentially alter 

their inflammatory response (e.g., antioxidants, 

nonsteroidal anti-inflammatory agents) for at 

least 6 days before exposure were not allowed 

to participate. A urine pregnancy test was performed on all females during the screening 

process and before each exposure.

Exposure of subjects to coarse CAPs.

Ambient air was drawn into an inlet duct 

on the roof of the U.S. EPA human studies facility (~ 30 m above ground level) in 

Chapel Hill at 5,000 L/min and transferred 

downward into the building to a PM10 inlet 

of the concentrator. The size selective inlet 

and the virtual impactors used to concentrate 

particles are identical to those developed by 

Demokritou et al. (2002). The major outward 

flow was 4,500 L/min for the first impaction 

stage and 450 L/min for the second impaction stage, giving a 50 L/min concentrated 

aerosol outflow. We diluted the concentrated 

aerosol with 150 L/min of room-temperature 

dilution air [relative humidity (RH) ~ 30%], 

which was added to provide enough airflow 

for the human subjects’ breathing requirements. The dilution air was passed through 

HEPA filters and charcoal to strip it of particles and gaseous air pollutants. We assessed 

PM concentrations in the chamber by gravimetric analysis of filters. We placed the filters 

immediately upstream of the inlet duct to 

the chamber, about 30 in from the subject’s 

mouth. We measured real-time concentrations upstream of the concentrator and in the 

chamber using a Fisher Scientific DataRam 

4 monitor (Franklin, MA) and used these 

concentrations to calculate the concentration factor, which ranged from 4- to 10-fold. 

We measured particle size distributions with 

a 3321 APS instrument (TSI Inc., St Paul, 

MN). Because coarse PM is not evenly distributed in a chamber of this size, each subject was seated with their mouths about 12 in 

from the chamber inlet duct. Even at that 

close distance, the subjects inhaled only 67% 

of the particles measured at the filter inlet. 

Table 1 shows the actual dose of particles 

inhaled by each subject.

Exposures were conducted in a specially 

designed Plexiglas chamber at approximately 

20°C and 40% RH. Participants were randomly exposed to filtered air and concentrated 

PM2.5–10 for 120 min, with intermittent exercise, on two separate occasions separated by at 

least 1 month. The exercise schedule consisted 

of 15 min of rest followed by 15 min of exercise on a recumbent bicycle, repeated four 

times over the 120-min exposure session, with 

a target ventilation of 20 L/min/m2 during 

exercise. During a training session, the workload needed for each subject to achieve the 

target minute ventilation was calculated. Most 

subjects achieved the target using a work load 

of 75 W; however, the tension on the exercise 

bike was adjusted according to each subject’s 

calculations.

End point measurements. Bronchoscopy 

with lavage. Subjects underwent bronchoscopy 

with lavage approximately 20 hr after the completion of each exposure, as described in detail 

in Huang et al. (2006). We quantified cell 

numbers by counting in a hemocytometer and 

assessed viability by exclusion of trypan blue 

dye. Viability exceeded 90% in all samples. 

Cells were stained using DiffQuik reagents 

purchased from Sigma (St. Louis, MO), and 

we determined differential cell counts [polymorphonuclear neutrophils (PMNs), macrophages, lymphocytes, monocytes, epithelial 

cells, and eosinophils] by counting at least 

300 cells under an oil-emersion lens. We 

stored bronchial lavage (BL) and bronchoalveolar lavage (BAL) fluid at –80°C, and at 

the end of the study we used commercially 

available kits to quantify levels of interleukin 

(IL)-6 and IL-8 (R&D Systems, Minneapolis, 

MN), prostaglandin E2 (PGE2; New England 

Nuclear, Boston, MA), α1-antitrypsin 

(ALPCO Diagnostics, Windham, NH), and 

total protein (BioRad, Hercules, CA).

Spirometry. We assessed pulmonary 

function with a SensorMedics Vmax system 

(VIASYS, Conshohocken, PA). We took 

measurements of forced vital capacity (FVC), 

forced expiratory volume in 1 sec (FEV1), and 

carbon monoxide diffusion capacity (DLCO) 

before, after, and approximately 20 hr after 

the completion of each exposure as described 

earlier (Ghio et al. 2000).

Cellular and soluble blood components. 

We collected venous blood immediately 

before and approximately 1 hr and 20 hr after 

the completion of each exposure. Basic blood 

chemistry, complete blood count with differential, and serum catecholamines were measured by LabCorp (Burlington, NC) on the 

day the blood was drawn. Plasma and serum 

was also frozen at –80°C for later analysis. 

We used commercially available ELISA kits to 

quantify levels of C-reactive protein (ALPCO 

Diagnostics, Windham, NH); D-dimer and 

von Willebrand’s factor (vWF; Diagnostica 

Stago, Parsippany, NY); factor VII, factor IX, 

prothrombin, tissue plasminogen activator 

Table 1. Basic demographic and PM concentration data.

Minute PM concentration Calculated PM dose

ventilation (μg/m3) (μg)a

Subject Sex Age (years) (L/min) Total Coarse Total Coarse

1 Male 29 21.7 170.3 159.6 297 278

2 Male 21 23.1 73.4 60.3 136 112

3 Female 22 20.1 232.8 196.9 375 317

4 Male 23 18.4 168.9 136.9 250 203

5 Male 26 21.3 100.0 75.0 171 128

6 Female 23 12.2 106.3 85.8 104 84

7 Female 22 26.1 56.1 56.1 117 117

8 Male 34 17.0 127.3 102.8 174 141

9 Male 28 26.2 27.4 23.7 58 50

10 Female 22 26.0 115.4 85.4 241 178

11 Male 34 22.7 120.9 106.2 220 193

12 Female 24 27.4 98.0 88.8 216 196

13 Female 20 24.5 36.5 31.8 63 55

14 Male 20 17.4 38.3 36.1 54 51

Mean ± SD 24.9 ± 4.7 21.5 ± 4.3 105.1 ± 58.3 89.0 ± 49.5 176.7 ± 95.9 150.3 ± 82.5

aCalculated PM dose (μg) = (minute ventilation × 120 min)/1,000 L × PM concentration × 0.67 (the estimated proportion 

of the particles being delivered to the airway, calculated by comparing PM values at the inlet to the chamber and a few 

inches away from a subject’s mouth). 
 Health effects of coarse PM

Environmental Health Perspectives • volume 117 | number 7 | July 2009 1091

(tPA), plasminogen, fibrinogen, and protein 

C (Enzyme Research Laboratories, South 

Bend, IN); and plasminogen activator inhibitor 1 (DakoCytomation, Carpenteria, CA).

Heart rate variability (HRV). We collected 

continuous ambulatory electrocardiograms 

(ECGs) for approximately 24 hr using a 3100A 

Zymed Holter System (Phillips, Andover, MA)

and processed them by standard Zymed algorithms. We sampled the ECGs at 120 Hz and 

stored all data on flash cards before processing. An electrocardiographic research nurse 

blinded to the particle exposure randomization then edited the sequence of ECG complexes to ensure proper labeling of each QRS 

complex. From the edited records, we assessed 

time domain [standard deviation of normalto-normal intervals (SDNN) and percentage 

of differences between adjacent normal-tonormal intervals that are > 50 msec (PNN50)]

and frequency domain [total, low-frequency 

(LF; 0.03–0.15 Hz), and high-frequency (HF;

0.15–0.4 Hz) power] variables for the 5-min

time periods immediately before exposure and 

approximately 1 hr and 20 hr after the completion of each exposure. We conducted measurements while subjects reclined quietly in a 

dark room for 30 min, with the final 10 min

being used for HRV analysis. In addition to 

the 5-min intervals, we also calculated SDNN 

and average SDNN for the entire 24-hr ambulatory monitoring period.

Statistical analysis. We assessed lung function, blood, and Holter measurements immediately before, 1 hr after, and 20 hr after each 

exposure. We assessed BAL/BL measurements 

only 20 hr postexposure. For analysis, we 

subtracted preexposure values from 1 hr and 

20 hr postexposure values and compared the 

air exposure differences with the CAP exposure differences for each person. Data in the 

figures are percent change in these differences 

per 10-mg/m3 increase in PM concentration in 

the exposure chamber. Because we took BAL 

measurements only 20 hr postexposure, we 

compared only those values during the statistical analysis. Concentration of coarse PM in the 

chamber is measured on a continuous scale and 

varies from subject to subject depending on the 

outdoor PM concentration that day. Table 

1 shows the inhaled and chamber concentrations during the CAP exposure. PM concentrations in the chamber during air exposures were 

low, but not zero. We used linear mixed effects 

models (R statistical software, version 2.3.1, 

lmer package) to test differences in response 

between the CAP and filtered air exposures. 

More specifically, we used a random intercept 

model to account for the subject-level variability and estimated the slope parameter that 

described an expected change in response as a 

function of PM concentration. We summarize 

the estimates of slope on the basis of a 10-mg/

m3 increase in PM concentration. We also 

report the mean and standard error associated 

with each end point. We used an α of 0.05 to 

determine statistical significance.

Results

Study population and exposure. Table 1 contains basic demographic PM concentration 

information. This study enrolled six female 

and eight male participants with a mean age 

of 24.9 years. All exposures began within 

30 min of 0945 hours to control for diurnal 

variations in physiologic response. Although 

we constructed the concentrator to concentrate only PM2.5–10, there is some concentration of PM1–2.5 (particles between 1 and 

2.5 μm). “Total PM” in Table 1 refers to the 

combination of all particles present in the 

chamber. We observed substantial variation 

in concentrated PM exposure reflecting the 

natural daily variation in PM concentration 

outside the facility. CAP exposures took place 

from June to December, and, as expected, 

coarse PM concentrations were higher in the 

warmer months (Figure 1).

Coarse PM caused small but significant 

changes in lung neutrophils and monocytes.

Total cell recoveries in the BL and BAL fluids 

did not differ between air- and CAP-exposed 

individuals. Figure 2 provides data for the cell 

differential end points. In the BAL fraction 

we observed a statistically significant 10.7% 

increase in percent PMNs per 10 μg/m3 of 

coarse PM (p = 0.0065), indicative of mild 

pulmonary inflammation. BAL PMN values 

in air-exposed individuals were 1.0 ± 0.30%. 

In the BL fraction, we observed a trend toward 

an increase in PMNs with increasing CAP

concentration, although the trend was not statistically significant. We observed a small, but 

statistically significant, 2.0% decrease in percent monocytes in the BL fraction (p = 0.05) 

per 10 μg/m3 of coarse PM. Monocyte levels 

in air-exposed individuals were 7.2 ± 0.8%. 

We observed no significant changes in any of 

the other cell types in either fraction.

Coarse PM caused a decrease in total 

protein in the BAL. We observed no differences in recovery of BL or BAL fluid between 

air- and CAP-exposed individuals. The group 

average return was within 10%, so soluble 

components were expressed per milliliter of 

lavage fluid. As shown in Figure 3, soluble 

markers of inflammation present in BAL 

and BL fluids (IL-6, IL-8, PGE2) were not 

changed after exposure to coarse CAPs for 

2 hr. However, we observed a 1.8% decrease 

in total protein in BAL fluid (p = 0.0191) per 

10 μg/m3 of coarse PM. Protein levels in BAL 

fluid of air-exposed individuals were 74.2 ± 

9.0 μg/mL. In an earlier study (Ghio et al. 

2000), we also reported decreased protein in 

lavage fluid of humans exposed to fine CAPs.

Coarse PM caused no changes in pulmonary 

function. We took lung function measurements 

before, immediately after, and again 20 hr after 

exposure to air and coarse CAPs. Relative to 

measurements taken before exposure, FEV1

and FVC did not show statistically significant 

changes either immediately or 20 hr after exposure to coarse CAPs (Figure 4). A recent study 

Figure 1. Correlation between coarse PM concentration in the exposure chamber and date of PM exposure. The solid line represents the linear regression 

line. The correlation of determination (r 2) is 0.55 

(p = 0.0025).

250

200

150

100

50

0

Coarse PM concentration (μg/m3

)

June

July

August

September

October

December

January

November

Figure 2. Changes in the percentage of each cell 

type in the BL and BAL fluids. Most participants 

had zero basophils and eosinophils in either fraction (data not shown).

Percent change per 10-μg/m3

increase in PM concentration

PMNs (%)

Macrophages (%)

Lymphocytes (%)

Monocytes (%)

–5 0 1 5 0 15

BL

BAL

Figure 3. Changes in inflammatory mediators in the 

BL and BAL fluids. A1AT, α1-antitrypsin.

IL-6

IL-8

PGE2

A1AT

Total protein

–6 –4 –2 0 2 4

Percent change per 10-μg/m3

increase in PM concentration

BL

BAL
Graff et al.

1092 volume 117 | number 7 | July 2009 • Environmental Health Perspectives

reported changes in pulmonary diffusing capacity (DLCO) for carbon monoxide in humans 

exposed to ultrafine carbon black particles 

(Pietropaoli et al. 2004). However, in this study 

we saw no change in DLCO either immediately 

or 20 hr after CAP exposure.

Coarse CAPs cause small changes in vascular factors involved in coagulation. We measured a number of soluble factors involved in 

clotting and coagulation before, immediately 

after, and again 20 hr after exposure to air or 

coarse CAPs. Relative to measurements taken 

before exposure, only tPA showed a significant change after CAP exposure (Figure 5). tPA 

concentration decreased 32.9% from the mean 

baseline level (p = 0.01) per 10-μg/m3 increase 

in CAP concentration when measured approximately 20 hr after exposure. Decreased tPA 

levels could potentially result in the formation 

of less plasmin, a compound that plays a key 

role in dissolving blood clots that may have 

formed in blood vessels. D-dimer concentration 

decreased 11.3% per 10 μg/m3 of coarse PM 

20 hr after exposure, but the decrease did not 

quite achieve statistical significance (p = 0.07). 

tPA and D-dimer concentrations in blood 

drawn before exposure were 6.5 ± 1.6 ng/mL

and 349 ± 61 ng/mL, respectively.

Other blood biomarkers. We also examined markers of systemic inflammatory processes, catecholamines, and lipids in the blood 

(data not shown). Coarse CAP exposure did 

not cause significant changes in C-reactive 

protein, catecholamines, triglycerides, or cholesterol (total, very-low-density, low-density, 

and high-density lipoproteins).

HRV. In a previous study (Devlin et al. 

2003), we reported that elderly healthy 

people exposed to fine CAPs had changes in 

both time- and frequency-domain variables as 

measured by Holter recording. In this study, 

we applied a Holter monitor to each subject before exposure, which the subject wore 

for 24 hr. We measured SDNN, a marker 

of overall HRV, using data from the entire 

monitoring period. We measured PNN50, 

LF, HF, and total power during three 5-min

periods when the subject was lying at rest: 

immediately before, immediately after, and 

20 hr after exposure to air or coarse CAPs. 

Relative to the measurements taken before

exposure, SDNN decreased 14.4% from the 

mean baseline level per 10-μg/m3 increase in 

CAP concentration during a resting period 

20 hr postexposure (p = 0.05) (Figure 6). We 

observed no statistically significant changes 

in any of the other HRV end points at either 

postexposure measurement and no changes in 

the 24-hr end points measurements.

Discussion

The recent development of second-generation 

particle concentrators has made it possible to 

examine the effects of real-time exposure to 

atmospheres in which size-fractionated PM is 

selectively concentrated. This study shows that 

an acute exposure of healthy young adults to 

concentrated coarse CAPs resulted in significant changes in indices of pulmonary inflammation, hemostasis, and autonomic nervous 

system balance. The mean coarse PM concentration (105.1 μg/m3) measured at the inlet 

to the exposure chamber in this study is not 

unrealistically high and can be found in many 

areas throughout the world, including locations in the U.S. Southwest. Furthermore, the 

actual PM concentration at the mouth of the 

subject was only 67% of that measured at the 

chamber inlet, resulting in average exposures 

to only 70.3 μg/m3. Table 1 shows the actual 

dose of PM inhaled by each person, taking 

ventilation into account. 

Coarse PM are preferentially deposited 

in the proximal region of the lung. They also 

contain the bulk of particle-bound biological 

material such as lipopolysaccharide, which is 

a known proinflammatory agent. Therefore,

we expected that coarse CAP exposure would 

elicit an inflammatory response (PMN influx) 

in the lung. Indeed, we did find a small but 

statistically significant increase in the percentage of PMNs in the BAL fluid. In a previous 

study, we exposed young, healthy volunteers 

to fine CAPs (PM2.5), divided into four concentrations quartiles of 0 (filtered air), 47.2, 

107.4, and 206.7 μg/m3 (Ghio et al. 2000). In 

the present study, the mean PM concentration 

(105.1 μg/m3) was very close to the mean concentration of the third quartile in the fine CAP

study (107.4 μg/m3) and resulted in an identical percentage of PMNs in the BAL fluid, 

suggesting that coarse and fine PM may be 

equally potent in inducing pulmonary inflammation. Other studies have not reported an 

influx of inflammatory cells into the lung after 

exposure of humans to CAPs. However, those 

studies used induced sputum to obtain cells 

from the respiratory tract rather than BAL, 

and we have found the latter is a more sensitive and less noisy method to measure lung 

inflammation, particularly when the percent 

influx of PMNs is small.

We did not observe decreases in lung function in this study, nor did we observe increases 

in soluble markers of pulmonary inflammation 

such as IL-6, IL-8, or PGE2. This is in agreement with other studies in which both healthy 

humans and those with pulmonary disease 

have been exposed to CAPs (Ghio et al. 2000; 

Gong et al. 2003a, 2003b, 2004a, 2008) and 

strengthens the notion that acute exposure to 

air pollution particles generally does not seem 

to result in substantial changes to the respiratory system. In contrast to CAP exposure, 

our previous studies in which humans were 

exposed to low levels of ozone have shown a 

marked decrease in pulmonary function and 

increase in inflammatory cells and cytokines 

(Devlin et al. 1991; Horstman et al. 1990), 

suggesting that particles and ozone exert their 

effects via dissimilar mechanisms.

In this study, we found decreased blood 

plasma tPA levels 20 hr after exposure to coarse 

CAPs. tPA is a protein that is involved in the 

breakdown of blood clots by catalyzing the 

conversion of plasminogen to plasmin, the 

major enzyme responsible for clot breakdown. 

Figure 4. Changes in measures of pulmonary function: immediately after exposure (Post) and approximately 20 hr after exposure (Follow-up).

FVC

FEV1

DLCO

–100 –50 0 50 100

Post

Follow-up

Percent change per 10-μg/m3

increase in PM concentration

Figure 5. Changes in mediators of coagulation: 

immediately after exposure (Post) and approximately 20 hr after exposure (Follow-up). PAI-1, 

plasminogen activator inhibitor-1. 

PAI-1

VWF

D-dimer

Factor VII

Factor IX

Plasminogen

Fibrinogen

TPA

Prothrombin

Protein C

–100 –50 0 50 100

Percent change per 10-μg/m3

increase in PM concentration

Post

Follow-up

Figure 6. Changes in resting HRV measurements: 

immediately after exposure (Post) and approximately 20 hr after exposure (Follow-up). 

SDNN

PNN50

Low frequency

High frequency

Total power

–100 –50 0 50 100 150

Percent change per 10-μg/m3

increase in PM concentration

Post

Follow-up
 Health effects of coarse PM

Environmental Health Perspectives • volume 117 | number 7 | July 2009 1093

Decreased tPA levels could inhibit the breakdown of any clots formed by particles, thus 

increasing the odds of a thromboembolic event. These findings add to the growing 

number of studies that have found associations 

between PM exposure and alterations in indices of hemostasis and thrombosis. We previously reported elevations in blood fibrinogen, a 

fibrin precursor and acute phase reactant, in the 

blood of healthy volunteers 24 hr after exposure to fine CAPs (Ghio et al. 2003). Increased 

blood fibrinogen has also been associated with 

exposure to air pollution in a number of panel 

studies (Chuang et al. 2007; Liao et al. 2005; 

Pekkanen et al. 2000; Ruckerl et al. 2007). We 

also reported an association between PM and 

vWF, a glycoprotein involved in endothelial 

cell activation, hemostasis, and platelet adhesion, in a panel of highway patrol troopers 

exposed to near-road air pollution (Riediker 

et al. 2004). Others have also reported associations between PM exposure and increased 

vWF (Liao et al. 2005), as well as plasminogen 

activator inhibitor (Chuang et al. 2007; Mills 

et al. 2005; Su et al. 2006). Taken as a whole, 

these studies indicate that exposure to PM has 

the potential to alter hemostatic balance function in the blood, favoring a prothrombogenic 

environment and interfering with fibrinolytic 

pathways. Whether these changes in hemostatic factors contribute to the triggering of cardiovascular and other thrombotic events after 

PM exposure remains to be established.

Analysis of HRV is a noninvasive method 

to assess the function of the autonomic nervous system. Reduced HRV is considered a 

prognostic marker for adverse cardiovascular 

events in patients with a prior myocardial 

infarction. Panel studies have consistently 

associated fine PM exposure with decreased 

HRV. Gold et al. (2000) reported an association between decreased SDNN and increased 

PM2.5, as did Liao et al. (1999) and Pope 

et al. (1999). Previous work from our group 

demonstrated that healthy elderly individuals 

without overt cardiovascular disease exposed 

to fine CAPs experienced decreased SDNN 

and HF HRV in 5-min resting intervals 

immediately and 24 hr after exposure (Devlin 

et al. 2003). A similar study by Gong et al. 

(2004a) involving healthy elderly individuals 

exposed to fine CAPs reported a significant 

decrease in SDNN 18 hr after exposure.

In this study we extend our earlier findings by showing that exposure to coarse CAPs

also results in decreased SDNN 20 hr after 

exposure. These results are in agreement with 

an earlier study which also reported decreased 

SDNN in healthy volunteers exposed to coarse 

CAPs (Gong et al. 2004b). They are also in 

agreement with a recent panel study in which 

we reported an association between coarse PM 

and decreased SDNN in asthmatics (Yeatts 

et al. 2007).

A note of caution must be exercised in 

interpreting these findings. We measured 

multiple end points in the lung, blood, and 

heart. Therefore, some of the statistically significant findings may have been due to chance 

alone. It will be important to see whether 

these findings can be replicated in our own 

and others’ studies.

There has been considerable discussion 

about the pathways by which PM can cause 

acute cardiovascular changes. One of the 

early thoughts was that particles could cause 

changes to the primary target organ, the lung, 

which would spill over into the vascular system and secondarily affect autonomic function. However, data from numerous human 

and animal toxicology studies suggest that 

CAPs do not induce sufficient pulmonary 

responses to cause these kinds of secondary effects. Indeed, if this were the case, one 

might expect that ozone, a powerful inducer 

of pulmonary inflammation, would be able 

to cause even more substantial cardiovascular 

changes than PM, which has not been shown 

to date.

Recent studies in rodents have hypothesized that ultrafine PM (PM0.1; those 

< 0.1 μm in diameter) may actually leave the 

lung and directly attack the cardiovascular system (Nemmar et al. 2002; Oberdorster et al. 

2002). Although this mechanism may play a 

role in cardiovascular effects caused by ultrafine PM, the large size of coarse PM makes 

it unlikely that they can pass directly into the 

circulation. However, it does not exclude the 

possibility that soluble components of coarse 

PM may find their way into the circulatory 

system. Recent in vitro experiments in our 

laboratory have shown that 40% of the activity of coarse PM that affects cultured airway 

epithelial cells resides in the water-soluble 

portion of the PM (data not shown).

A third possibility is that PM, regardless 

of size, may affect the cardiovascular system 

through nerve impulses transmitted from 

the lung to the brain. Ozone-induced decrements in lung function are thought to be 

mediated via interaction of the pollutant with 

C-fibers innervating the lung in humans and 

dogs (Bromberg and Koren 1995; Coleridge 

et al. 1993; Passannante et al. 1998). 

Administration of β-adrenergic receptor and 

muscarinic receptor antagonists effectively 

blocked PM-induced cardiac oxidative stress 

in rats (Rhoden et al. 2005). Capsazepine, 

a selective antagonist of the vanilloid receptor present on pulmonary C-fibers, blunt 

PM-induced changes in cardiac oxidative 

stress and edema in rats (Ghelfi et al. 2008). 

Tunnicliffe et al. (2001) reported HRV 

changes but no respiratory system changes in 

humans exposed to sulfur dioxide, suggesting 

that a cardiac autonomic effect can be triggered by upper-airway irritant receptors.

Conclusions

The results of this study showed that young, 

healthy people experience mild acute physiologic effects when exposed to environmentally 

relevant coarse air pollution PM. The results of 

this study are generally consistent with those 

of previously published studies examining the 

effects of both coarse and fine PM, suggesting 

that both particle size fractions are roughly 

equivalent in inducing cardiopulmonary 

changes in healthy humans. However, given 

the large number of end points typically measured in these studies, the relatively small number of positive findings makes it important for 

these findings to be replicated in future studies.

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