Showing papers by "Gerard Hoek published in 2011"

Black carbon as an additional indicator of the adverse health effects of airborne particles compared with PM10 and PM2.5.

Abstract: Background: Current air quality standards for particulate matter (PM) use the PM mass concentration [PM with aerodynamic diameters ≤ 10 μm (PM10) or ≤ 2.5 μm (PM2.5)] as a metric. It has been suggested that particles from combustion sources are more relevant to human health than are particles from other sources, but the impact of policies directed at reducing PM from combustion processes is usually relatively small when effects are estimated for a reduction in the total mass concentration. Objectives: We evaluated the value of black carbon particles (BCP) as an additional indicator in air quality management. Methods: We performed a systematic review and meta-analysis of health effects of BCP compared with PM mass based on data from time-series studies and cohort studies that measured both exposures. We compared the potential health benefits of a hypothetical traffic abatement measure, using near-roadway concentration increments of BCP and PM2.5 based on data from prior studies. Results: Estimated health effects of a 1-μg/m3 increase in exposure were greater for BCP than for PM10 or PM2.5, but estimated effects of an interquartile range increase were similar. Two-pollutant models in time-series studies suggested that the effect of BCP was more robust than the effect of PM mass. The estimated increase in life expectancy associated with a hypothetical traffic abatement measure was four to nine times higher when expressed in BCP compared with an equivalent change in PM2.5 mass. Conclusion: BCP is a valuable additional air quality indicator to evaluate the health risks of air quality dominated by primary combustion particles.

In vitro toxicity of particulate matter (PM) collected at different sites in the Netherlands is associated with PM composition, size fraction and oxidative potential - the RAPTES project

Abstract: Background Ambient particulate matter (PM) exposure is associated with respiratory and cardiovascular morbidity and mortality. To what extent such effects are different for PM obtained from different sources or locations is still unclear. This study investigated the in vitro toxicity of ambient PM collected at different sites in the Netherlands in relation to PM composition and oxidative potential.

Stability of measured and modelled spatial contrasts in NO(2) over time.

Abstract: Objectives Land use regression (LUR) modelling is a popular method to estimate outdoor air pollution concentrations at the home and/or work addresses of individual subjects in epidemiological studies. Typically, such models are constructed using measurements from dedicated monitoring campaigns lasting up to 1 year. It is unknown to what extent such models can adequately predict concentrations in earlier or later time periods. We tested the stability of measured and modelled spatial contrasts in outdoor nitrogen dioxide (NO 2 ) pollution across the Netherlands over 8 years. Methods NO 2 measurements were conducted at 40 locations in the Netherlands in 1999–2000. In 2007, NO 2 was again measured at 144 locations, of which 35 were the same as in 1999–2000. This enabled us to compare measurements as well as model predictions between the two time periods. Results NO 2 measurements conducted in 2007 agreed well with NO 2 measurements taken in 1999–2000 at the same locations (R 2 =0.86). LUR models from 1999–2000 and 2007 explained 85% and 86% of observed spatial variance, respectively. The 2007 LUR model explained 77% of spatial variability in the 1999–2000 measurements and the 1999–2000 model explained 81% of variability in the 2007 measurements. Conclusion We found good agreement between measured spatial contrasts in outdoor NO 2 in 1999–2000 and 2007. LUR models predicted spatial contrast 8 years in the past (2007 model) and 8 years in the future (1999–2000 model) well. This supports the use of LUR models in epidemiological studies with health data available for a later or earlier timepoint.

Do the Health Benefits of Cycling Outweigh the Risks

Abstract: Although from a societal point of view a modal shift from car to bicycle may have beneficial health effects due to decreased air pollution emissions and increased levels of physical activity, shifts in individual adverse health effects such as higher exposure to air pollution and risk of a traffic accident may prevail. We have summarized the literature for air pollution, traffic accidents, and physical activity using systematic reviews supplemented with recent key studies. We quantified the impact on all-cause mortality when 500,000 people would make a transition from car to bicycle for short trips on a daily basis in the Netherlands. We estimate that beneficial effects of increased physical activity are substantially larger (3-14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8-40 days lost) and the increase in traffic accidents (5-9 days lost). Societal benefits are even larger because of a modest reduction in air pollution and traffic accidents. On average, the estimated health benefits of cycling were substantially larger than the risks relative to car driving for individuals shifting their mode of transport.

Land use regression model for ultrafine particles in Amsterdam.

Abstract: There are currently no epidemiological studies on health effects of long-term exposure to ultrafine particles (UFP), largely because data on spatial exposure contrasts for UFP is lacking. The objective of this study was to develop a land use regression (LUR) model for UFP in the city of Amsterdam. Total particle number concentrations (PNC), PM10, PM2.5, and its soot content were measured directly outside 50 homes spread over the city of Amsterdam. Each home was measured during one week. Continuous measurements at a central urban background site were used to adjust the average concentration for temporal variation. Predictor variables (traffic, address density, land use) were obtained using geographic information systems. A model including the product of traffic intensity and the inverse distance to the nearest road squared, address density, and location near the port explained 67% of the variability in measured PNC. LUR models for PM2.5, soot, and coarse particles (PM10, PM2.5) explained 57%, 76%, and 37% of the variability in measured concentrations. Predictions from the PNC model correlated highly with predictions from LUR models for PM2.5, soot, and coarse particles. A LUR model for PNC has been developed, with similar validity as previous models for more commonly measured pollutants.

Respiratory effects of commuters' exposure to air pollution in traffic.

Abstract: Background:Much time is spent in traffic, especially during rush hours, when air pollution concentrations on roads are relatively high. Controlled exposure studies have shown acute respiratory effects of short, high exposures to air pollution from motor vehicles. Acute health effects of lower real-l

Contrasts in Oxidative Potential and Other Particulate Matter Characteristics Collected Near Major Streets and Background Locations

Abstract: Background: Measuring the oxidative potential of airborne particulate matter (PM) may provide a more health-based exposure measure by integrating various biologically relevant properties of PM into a single predictor of biological activity. Objectives: We aimed to assess the contrast in oxidative potential of PM collected at major urban streets and background locations, the associaton of oxidative potential with other PM characteristics, and the oxidative potential in different PM size fractions. Methods: Measurements of PM with aerodynamic diameter ≤ 10 μm (PM10), PM with aerodynamic diameter ≤ 2.5 μm (PM2.5), soot, elemental composition, and oxidative potential of PM were conducted simultaneously in samples from 8 major streets and 10 urban and suburban background locations in the Netherlands. Six 1-week measurements were performed at each location over a 6-month period in 2008. Oxidative potential was measured as the ability to generate hydroxyl radicals in the presence of hydrogen peroxide in all PM10 samples and a subset of PM2.5 samples. Results: The PM10 oxidative potential of samples from major streets was 3.6 times higher than at urban background locations, exceeding the contrast for PM mass, soot, and all measured chemical PM characteristics. The contrast between major streets and suburban background locations was even higher (factor of 6.5). Oxidative potential was highly correlated with soot, barium, chromium, copper, iron, and manganese. Oxidative potential of PM10 was 4.6 times higher than the oxidative potential of PM2.5 when expressed per volume unit and 3.1 times higher when expressed per mass unit. Conclusions: The oxidative potential of PM near major urban roads was highly elevated compared with urban and suburban background locations, and the contrast was greater than that for any other measured PM characteristic.

In-Traffic Air Pollution Exposure and CC16, Blood Coagulation, and Inflammation Markers in Healthy Adults

Abstract: Background: Exposure to traffic-related air pollution is a risk factor for cardiovascular events, probably involving mechanisms of inflammation and coagulation. Little is known about effects of the...

Do the Health Benefits of Cycling Outweigh the Risks

Abstract: Although from a societal point of view a modal shift from car to bicycle may have beneficial health effects due to decreased air pollution emissions and increased levels of physical activity, shifts in individual adverse health effects such as higher exposure to air pollution and risk of a traffic accident may prevail. We have summarized the literature for air pollution, traffic accidents, and physical activity using systematic reviews supplemented with recent key studies. We quantified the impact on all-cause mortality when 500,000 people would make a transition from car to bicycle for short trips on a daily basis in the Netherlands. We estimate that beneficial effects of increased physical activity are substantially larger (3-14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8-40 days lost) and the increase in traffic accidents (5-9 days lost). Societal benefits are even larger because of a modest reduction in air pollution and traffic accidents. On average, the estimated health benefits of cycling were substantially larger than the risks relative to car driving for individuals shifting their mode of transport.

Long-term Exposure to Traffic-related Air Pollution and Type 2 Diabetes Prevalence in a Cross-sectional Screening-study in the Netherlands

Abstract: Air pollution may promote type 2 diabetes by increasing adipose inflammation and insulin resistance. This study examined the relation between long-term exposure to traffic-related air pollution and type 2 diabetes prevalence among 50- to 75-year-old subjects living in Westfriesland, the Netherlands. Participants were recruited in a cross-sectional diabetes screening-study conducted between 1998 and 2000. Exposure to traffic-related air pollution was characterized at the participants' home-address. Indicators of exposure were land use regression modeled nitrogen dioxide (NO2) concentration, distance to the nearest main road, traffic flow at the nearest main road and traffic in a 250 m circular buffer. Crude and age-, gender- and neighborhood income adjusted associations were examined by logistic regression. 8,018 participants were included, of whom 619 (8%) subjects had type 2 diabetes. Smoothed plots of exposure versus type 2 diabetes supported some association with traffic in a 250 m buffer (the highest three quartiles compared to the lowest also showed increased prevalence, though non-significant and not increasing with increasing quartile), but not with the other exposure metrics. Modeled NO2-concentration, distance to the nearest main road and traffic flow at the nearest main road were not associated with diabetes. Exposure-response relations seemed somewhat more pronounced for women than for men (non-significant). We did not find consistent associations between type 2 diabetes prevalence and exposure to traffic-related air pollution, though there were some indications for a relation with traffic in a 250 m buffer.

Seasonal patterns of outdoor PM infiltration into indoor environments: review and meta-analysis of available studies from different climatological zones in Europe

Abstract: Epidemiologists have observed higher risks for exposure to ambient particulate matter (PM) in the summer than in other seasons. This increased risk may be partly due to seasonal behaviour and higher exposures to indoor PM in the summer in relation to outdoor pollutant levels during winter when windows are kept closed and less time is spent outdoors. In this report, we analyse data from six European studies, based on three different methods of estimating outdoor to indoor infiltration factors, with the aim of characterizing the geographical and seasonal patterns of PM infiltration. The highest infiltration levels were observed for the summer in both a European combined dataset consisting of 382 observations of the average PM2.5 infiltration factor for 1 day to 2weeks in regional data sets for Northern, Central and Southern Europe as well as for all ten cities individually. Th lowest values were observed for the winter, with spring and autumn displaying intermediate values. In all datasets and cities, the variability between residences and days within each season was much higher than the seasonal trend. PM10 data were available from two studies, revealing that the PM10 infiltration factors ranged from 70 to 92% of the corresponding PM2.5 values. Some differences between the studies may be associated with the study designs and applied methods of determining the infiltration factor. The ratio of summer to winter PM2.5 infiltration ranged from 1.3 in Rome to 2.3 in Helsinki, and the corresponding regional ratio ranged from 1.5 in Central Europe to 1.8 in Northern and Southern Europe. It is suggested that similar differences can be expected in epidemiological concentration–response relationships due to the modification in seasonal exposure associated with buildings and time spent indoors.

Temporal variations of atmospheric aerosol in four European urban areas

Abstract: The concentrations of PM10 mass, PM2.5 mass and particle number were continuously measured for 18 months in urban background locations across Europe to determine the spatial and temporal variability of particulate matter. Daily PM10 and PM2.5 samples were continuously collected from October 2002 to April 2004 in background areas in Helsinki, Athens, Amsterdam and Birmingham. Particle mass was determined using analytical microbalances with precision of 1 μg. Pre- and post-reflectance measurements were taken using smoke-stain reflectometers. One-minute measurements of particle number were obtained using condensation particle counters. The 18-month mean PM10 and PM2.5 mass concentrations ranged from 15.4 μg/m3 in Helsinki to 56.7 μg/m3 in Athens and from 9.0 μg/m3 in Helsinki to 25.0 μg/m3 in Athens, respectively. Particle number concentrations ranged from 10,091 part/cm3 in Helsinki to 24,180 part/cm3 in Athens with highest levels being measured in winter. Fine particles accounted for more than 60% of PM10 with the exception of Athens where PM2.5 comprised 43% of PM10. Higher PM mass and number concentrations were measured in winter as compared to summer in all urban areas at a significance level p < 0.05. Significant quantitative and qualitative differences for particle mass across the four urban areas in Europe were observed. These were due to strong local and regional characteristics of particulate pollution sources which contribute to the heterogeneity of health responses. In addition, these findings also bear on the ability of different countries to comply with existing directives and the effectiveness of mitigation policies.

Parental education and lung function of children in the PATY study

Abstract: Studies of the relationships between low socio-economic status and impaired lung function were conducted mainly in Western European countries and North America. East–West differences remain unexplored. Associations between parental education and lung function were explored using data on 24,010 school-children from eight cross-sectional studies conducted in North America, Western and Eastern Europe. Parental education was defined as low and high using country-specific classifications. Country-specific estimates of effects of low parental education on volume and flow parameters were obtained using linear and logistic regression, controlling for early life and other individual risk factors. Meta-regressions were used for assessment of heterogeneity between country-specific estimates. The association between low parental education and lung function was not consistent across the countries, but showed a more pronounced inverse gradient in the Western countries. The most consistent decrease associated with low parental education was found for peak expiratory flow (PEF), ranging from −2.80 to −1.14%, with statistically significant associations in five out of eight countries. The mean odds ratio for low PEF (<75% of predicted) was 1.34 (95% CI 1.06–1.70) after all adjustments. Although social gradients were attenuated after adjusting for known risk factors, these risk factors could not completely explain the social gradient in lung function.

Risk assessment of diesel exhaust and lung cancer: combining human and animal studies after adjustment for biases in epidemiological studies.

Abstract: Background: Risk assessment requires dose-response data for the evaluation of the relationship between exposure to an environmental stressor and the probability of developing an adverse health effect. Information from human studies is usually limited and additional results from animal studies are often needed for the assessment of risks in humans. Combination of risk estimates requires an assessment and correction of the important biases in the two types of studies. In this paper we aim to illustrate a quantitative approach to combining data from human and animal studies after adjusting for bias in human studies. For our purpose we use the example of the association between exposure to diesel exhaust and occurrence of lung cancer. Methods: Firstly, we identify and adjust for the main sources of systematic error in selected human studies of the association between occupational exposure to diesel exhaust and occurrence of lung cancer. Evidence from selected animal studies is also accounted for by extrapolating to average ambient, occupational exposure concentrations of diesel exhaust. In a second stage, the bias adjusted effect estimates are combined in a common effect measure through meta-analysis. Results: The random-effects pooled estimate (RR) for exposure to diesel exhaust vs. non-exposure was found 1.37 (95% C.I.: 1.08-1.65) in animal studies and 1.59 (95% C.I.: 1.09-2.10) in human studies, whilst the overall was found equal to 1.49 (95% C.I.: 1.21-1.78) with a greater contribution from human studies. Without bias adjustment in human studies, the pooled effect estimate was 1.59 (95% C.I.: 1.28-1.89). Conclusions: Adjustment for the main sources of uncertainty produced lower risk estimates showing that ignoring bias leads to risk estimates potentially biased upwards.

Cycling: de Hartog et al. Respond

Abstract: We thank Int Panis for his thoughtful comments on our article (de Hartog et al. 2010), and we broadly agree with his comments. In fact, we discussed most of the issues—including the limitation to impact on mortality, sensitive subgroups, route choice, and activity substitution—in our paper. The first issue discussed by Int Panis is whether we underestimated the difference in minute ventilation between cyclists and car drivers; however, his comment was based on a recent Belgian study (Int Panis et al. 2010) that was not published at the time of our study. In our analysis we used a ratio of 2.2 [the average of two Dutch studies that closely agreed (van Wijnen et al. 1995; Zuurbier et al. 2009)], whereas the Belgian study (Int Panis et al. 2010) found a ratio of 4.3. The difference is probably explained in part by differences in cycling speed: 12 km/hr in the recent Dutch study (Zuurbier et al. 2009) and > 19 km/hr in the Belgian study (Int Panis et al. 2010). In urban areas, the average cycling speed is about 15 km/hr, including stop time. Rather than replacing the previous estimates by with the newer Belgian estimate, we believe that the best current estimate would be the average of the ratios of the three available studies. This would lead to a ratio of 2.9. Use of this ratio based on more studies clearly would not tip the balance between cycling and car driving as Int Panis suggests. We think it is stretching the data too much to use deposited particle mass (actually 5.9–8.99 higher in the Belgian study) for the analysis, because the long-term epidemiological studies we used are based on concentrations measured in outdoor air. In the most likely estimate we provided for air pollution [based on black smoke, which better represents traffic exposures than PM2.5 (particulate matter < 2.5 μm in aerodynamic diameter)], even including these estimates would not make a difference. As we noted in the “Discussion” of our article (de Hartog et al. 2010), cyclists have more opportunity in urban areas to choose low-exposure routes. This would indeed result in smaller differences in inhaled doses between cyclists and car drivers than we used. We agree that we may have overestimated the air pollution risks related to cycling because, in general, subjects who cycle are healthier than those who respond in long-term epidemiological studies. However, with increasing evidence that air pollution—through oxidative stress and inflammation—may also increase preclinical cardiovascular disease, including atherosclerosis (Brook et al. 2010), long-term effects of air pollution are not limited to mortality in the most sensitive subjects. Another issue deals with the large number of nonfatal bicycle accidents reported in a recent assessment in Belgium (Aertsens et al. 2010). We do not want to downplay the importance of these accidents; however, because Aertsens et al. (2010) exclusively reported accidents in cyclists, the study cannot be used in a comparative assessment of the risks of cyclists and car drivers, the topic of our paper. There is therefore no basis for Int Panis’s statement that inclusion of this information could easily have tipped the balance between risks and benefits. As we discussed in our article (de Hartog et al. 2010), we also did not take into account the benefits of physical activity on quality of life and other nonfatal health effects. We welcome an attempt to systematically make this assessment. In an assessment of traffic accident risks and benefits from air pollution and physical activity in the general population using disability-adjusted life years (DALYs), Woodcock et al. (2009) found that about about 80% of the calculated DALYs of all stressors were due to loss in life years, so we do not expect our conclusion to be much affected when morbidity is assessed. Finally, we fully agree with the statements about the importance of reducing risks from accidents and air pollution for commuters. Our paper should not be interpreted as a plea for ignoring these important risks.

Health Impact Assessment Of PM10 And EC In1985–2008 In The City Of Rotterdam,The Netherlands

Abstract: The health impact assessment (HIA) PM10 and elemental carbon (EC) was investigated in the period 1985–2008 in the city of Rotterdam. The spatial distribution of the concentrations was modelled by the URBIS model. The modelling results for 2008 were validated by PM10 and EC measurements at various locations in Rotterdam. This paper describes the HIA related to improved air quality in the period 1985-2008: at urban background locations 18 µg.m -3 PM10 and 2 µg.m -3 EC. The gain in life years saved due to long-term exposure to PM10 and EC in this period was, respectively, 13 and 12 months per person. The similar health impacts for PM10 and EC suggests that a reduction of combustion aerosol was important for the reduction in health impact of PM10. It is concluded that EC is a more adequate indicator for HIA of traffic measures than PM10.

Health impact assessment of PM10 and EC in the city of Rotterdam (the Netherlands) in the period 1985-2008

Abstract: In the framework of the Netherlands Policy Support Program on PM (" BOPII "), the trend of PM 10 and elemental carbon (EC) concentrations and related health impact has been assessed in the city of Rotterdam in the period 1985-2008. EC is regarded an indicator for exhaust emissions of " combustion aerosol ". In 1985-2008, international, national and local measures have been implemented to reduce in particular exhaust emissions of combustion aerosol by road traffic. However, the annual growth of road traffic kilometers in the same period was 1.5% on inner-urban roads and 3% at motorways in the Netherlands. Despite the volume growth of road traffic, it is concluded that after 1995, road traffic emissions of PM 10 and EC on urban roads have decreased, while on non-urban roads these emissions remained constant. Since 2003 monitoring data of EC show no decreasing trend which suggests that exhaust emissions by the growing traffic volume are no longer compensated by cleaner vehicles. Our study shows, that in Rotterdam in the period 1985-2008 the air quality of PM 10 and EC improved significantly both at urban background and near heavy traffic locations. This results in a gain in life years on average of 13±6 months (PM 10) or 12±8 months (EC) for the population in Rotterdam. The health impact for PM 10 and EC is similar though the population weighted PM 10 concentration dropped on average 18 µg.m-3 , while for EC this was 2 µg.m-3. From research in the Netherlands it is concluded that 70% of the decrease in PM 10 concentrations the last decades is related to secondary inorganic aerosol and " only " for 10% to primary PM emissions, including combustion aerosol. The similarity in health impact for PM 10 and EC suggests that the health impact of PM 10 is mainly related to the contribution of combustion aerosol in PM 10 and less to the contribution of secondary inorganic aerosol. This demonstrates that EC is a more sensitive indicator (compared to PM 10) to monitor the health effects of traffic measures. Also, it is concluded that measures directed to reduce combustion aerosol (e.g. exhaust emissions of road traffic and (inland) shipping) are more effective to reduce health effects of air quality than reducing PM 10 in general. It is noted, that EC is likely not causing the health effects but acts as a proxy for the mass of combustion …

Variation of elemental composition of particulate matter between and within 20 study areas in europe

Abstract: Background and Aims: Recent research has indicated the importance of particulate matter (PM) composition on adverse health effects. Furthermore, knowledge of PM composition can be used to apportion...