EFFECTS OF FINE AND ULTRAFINE PARTICLES ON RESPIRATORY AND CARDIOVASCULAR HEALTH

Project leader: Juha Pekkanen, National Public Health Institute (KTL), P.O.Box 95,
FIN-70701 Kuopio, Finland, tel. +358-17-201 368, e-mail: Juha.Pekkanen*ktl.fi
 
 

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TIIVISTELMÄ SUOMEKSI

Researchers:
Kirsi Timonen, Kuopio University Hospital, tel. +358-17-173201, e-mail: Kirsi.Timonen@kuh.fi
Pekka Tiittanen, KTL, tel. +358-17-201 344, e-mail: Pekka.Tiittanen@ktl.fi
Pasi Penttinen, KTL, tel. +358-17-201 393, e-mail: Pasi.Penttinen@ktl.fi
Timo Lanki, KTL, tel. +358 -17-201 326, e-mail: Timo.Lanki@ktl.fi
Marko Vallius, KTL, tel. +358-17-201 483, e-mail: Marko.Vallius@ktl.fi
Juhani Ruuskanen, University of Kuopio, tel. +358-17-163 227, e-mail: Juhani.Ruuskanen@uku.fi
Aadu Mirme, University of Tartu, Estonia, tel. +372-7-484 564, e-mail: Mirme@ut.ee

Consortium: Urban air particles and environmental health
Financing SYTTY organisation: The Academy of Finland
Funding from SYTTY / Total funding of project (€): 98827 / 655413
Person-months of work funded by SYTTY / Total person-months of work: 38,5 / 206,5

KEY WORDS: ultrafine particles, fine particles, respiratory health, cardiovascular health
 

EXTENDED ABSTRACT

1 Introduction

Daily mortality, especially respiratory and cardiovascular mortality, has been associated with daily variation of air pollution in several epidemiological studies. The findings seem plausible, as air pollution has also been found to be associated with respiratory and cardiovascular hospital admissions, respiratory symptoms and pulmonary function. The focus of current research is on the cardiovascular effects of particulate matter. As cardiovascular causes account for half of the deaths in Europe, the possible association with particulate air pollution has far-reaching implications.

In most epidemiological studies, particulate matter has been characterised as the concentration of particles less than 10 µm (PM10), but it is not clear which fraction(s) and what characteristics of particulate matter are responsible for the observed health effects. The two leading theories are that the health effects are either due to the very large number of ultrafine particles (particles less than 100 nm) or due to the chemical composition of particles. A plausible mechanism for cardiovascular effects has not yet been established.

The aims of the present study were, first, to improve exposure assessment of particles by assessing the size distributions and inter-relationships of particles, and elemental compositions of fine particles (less than 2.5 µm), and second, to investigate short-term effects of ultrafine and fine particles on cardiorespiratory health. Overall aim was to provide improved scientific basis for risk assessment of air pollution.

2 Methods

The present study consists of three subprojects, namely ULTRA 1, ULTRA 2 and APHEA2.

During winter 1996-97, 78 adult asthmatics were followed daily for six months in Helsinki (ULTRA 1). The subjects measured every morning, afternoon and evening their peak expiratory flow (PEF) and kept a daily diary on respiratory symptoms. In addition, their spirometric lung function was measured biweekly at a clinic. Exposure to air pollution was characterized by measurements of particle mass (PM10, PM2.5, PM1), number concentrations of particles of different sizes, especially ultrafine particles, and gaseous pollutants. In addition, the elemental composition of the PM2.5 filters, and absorption coefficient (marker for elemental carbon) of all filters was measured. The air quality monitoring was done at the same time in the Netherlands and Germany.

The second panel study (ULTRA 2) had a focus on cardiovascular outcomes. During winter 1998 - spring 1999 in Helsinki, 50 elderly persons with coronary heart disease were followed for 6 months with biweekly intensive clinic examinations. During the clinic visit measurements were made of cardiopulmonary function (spirometry, 30 min electrocardiography monitoring, blood pressure) and of a biomarker for lung damage from urine (Clara cell protein, CC16). The subjects also kept daily diary on cardiac and respiratory symptoms.
Similar panel studies were conducted in the Netherlands and Germany at the same time (only the results for Helsinki are presented here). Special emphasis was put on the standardization of the methods in the three centers. The Standard operating procedures (SOPs) and operating procedures used in the project can be found on the project’s homepage (www.ktl.fi/ultra) as well as the study manual.

Concurrently with the panel study, air pollution was monitored using the methodology adopted in ULTRA I. In a sub-study, daily indoor and personal PM2.5 concentrations were measured as well as hourly personal PM2.5 concentrations.

In addition to the panel studies, a study based on death register data was carried out. Effects of air pollution on daily mortality in Helsinki metropolitan area (years 1988-1996) were evaluated in the framework of a EU-study, in which 29 European cities took part (APHEA2).

3 Results and discussion

ULTRA 1
There were 57 subjects who completed the follow-up and were included in the analyses. During the study period, the median (range) 24-h concentration of PM10 was 13.5 (3.8–73.7) µg/m3, PM2.5 8.4 (2.4-38.3) µg/m3, PM1 5.6 (1.0-22.9) µg/m3, and number of ultrafine particles 15 600 (3700 – 46 500) n/cm3. There was poor correlation between the number of ultrafine particles and PM2.5 (r=0.23). Diurnal variation in ultrafine concentrations followed the rush hours of traffic. The PM2.5 levels differed significantly between the study centers, but the ultrafine concentrations did not.

When the Finnish data was divided into winter and spring periods, it was observed that PM2.5 and PM10 concentrations differed by pattern during resuspended dust episodes as PM10 was influenced more markedly by seasonal phenomena. PM1 concentrations followed PM2.5 concentrations fairly well throughout the measurement period and thus seem to originate from the same sources.

The number concentrations measured in different places in Helsinki showed high correlation, especially in areas where traffic followed similar patterns (R about 0.8). During the working days concentration averages of 10 min – 1 h seem to be good representatives of concentration variation in relatively large areas in the city.

Daily mean number concentration of particles, but not particle mass, was negatively associated with self-monitored daily PEF deviations. The strongest effects were seen for particles in the ultrafine range. however, the effect of ultrafine particles could not definitely be separated from other traffic generated pollutants, namely NOx and CO. No associations were observed with respiratory symptoms or medication use.

Daily number concentration of accumulation mode particles (diameter 0.1-1.0 µm) was consistently associated with PEF rate measured biweekly with spirometry. Negative non-significant associations were observed with ultrafine particles, but no associations with PM10.

ULTRA 2
In Helsinki, there were 47 subjects who completed the follow-up and altogether 515 clinical visits. During the study period, the median (range) daily concentrations of particulate air pollution were as follows: PM2.5: 10.6 (3.1-39.8) µg/m3; ultrafine particles 15 100 (2300-50 300) n/cm3, and accumulation mode particles 1200 (340-3800) n/cm3.

Median Pearson’s R between personal and outdoor PM2.5 was 0.76 and between corresponding absorption coefficients 0.81. The relatively high correlations provide support for using fixed-measurements as a measure of exposure to PM2.5 in epidemiological studies.

Ultrafine particles were not associated with urinary CC16 concentrations. In contrast, the CC16 concentrations seemed to increase with increasing daily levels of PM2.5 in Helsinki, especially among subjects with lung diseases. However, this was not observed in the other two ULTRA centers. The result suggests that exposure to particulate air pollution can increase epithelial barrier permeability in lungs.

Air pollution was not associated with SDNN, a measure of overall heart rate variability (HRV). Ultrafine particles were associated with decreased LF/HF –ratio, a measure of HRV indicating balance between sympathetic and parasympathetic input to the heart. PM2.5 was associated with decreased HF (a measure of parasympathetic input to the heart) in Helsinki, but not consistently in the other centers. However, PM2.5 was associated with decreased SDNN and HF in all centers among subjects with no beta-blocker medication.

The number of accumulation mode particles and PM2.5 were associated with increased risk of ST segment depressions, i.e. ischaemic ECG changes, during mild exercise test. Ultrafine particles had a smaller effect , which was independent of the PM2.5. According to preliminary analyses not only the daily levels but also hourly changes in particulate matter are associated with occurrence of ST segment depressions. The results suggest that the effect of particulate air pollution on cardiovascular morbidity is at least partly mediated through ischaemia.

PM2.5 was also associated with some cardiac and respiratory symptoms  (e.g. shortness of breath and phlegm incidence). In contrast, ultrafine particles were only weakly associated with some symptoms.

The analyses on the effects of particle composition on health have been started. Elemental composition of particles will be linked to different source categories. According to preliminary source apportionment analyses the five main source factors are the same in ULTRA 1 and ULTRA 2, namely long-range transport, local traffic, crustal material, residual oil burning, and salt or salt/lead.

APHEA 2
In Helsinki, PM10 was associated with respiratory mortality, ozone with respiratory and total mortality. Looking at all of the cities in APHEA2, the effect of PM10 on mortality was found to be modified with factors like NO2 concentration and temperature.

The database collected on hourly and daily concentrations of air pollutants gives tools for better exposure assessment, design of control strategies, and air quality monitoring. The results of the project can be used to develop standards for air quality in Finland, Europe and WHO, and thus to reduce the health effects associated with exposure to particulate matter in ambient air. The study also provided indirect information on the mechanisms of air pollution effect, which can be used as a basis for further studies trying to give plausible biological explanations for the effects.

4 Conclusions

Measurement of PM1 does not seem to add new information to that obtained with conventional PM2.5 measurements. The poor correlation between PM2.5 and ultrafine concentrations underlines the importance of using both particle number and mass concentrations to evaluate urban air quality. Outdoor PM2.5 concentrations were shown to be a fairly good measure of personal exposure to PM2.5.

The fine and ultrafine particles in Helsinki were associated with adverse health effects in both adult asthmatics and in elderly persons with coronary heard disease. Fine particles and ultrafine particles affected the peak expiratory flow among the asthmatics. Among the elderly persons, PM2.5 was associated with some decreased heart rate variability indices, especially in persons with no beta-blocker medication, ultrafine particles with changed balance between sympathetic and parasympathetic input to heart. Increased epithelial barrier permeability in lungs was observed in association with PM2.5. Fine particles were more strongly associated with increased risk of ischaemic changes in ECG than ultrafine particles. Overall, many of the endpoints showed inconsistent results between the three study centers.
The hypothesis of ultrafine particles being mainly responsible for the health effects of particulate air pollution was not supported. It seems that the health effects of ultrafine particles and particle mass are independent of each other. The characteristics of the city and personal characteristics, like medication use, modify the effects. Next step in the study is to look further at the effect of panel composition on the observed effects and to try to explain the health effects by the elemental composition of the particles.

The results of the project will aid decision making on both national and international air quality standards.
 

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