Biomedical subjects

G Hoek

Publications and source records attributed to G Hoek.

57 records · Page 4Linked to original sources

PubMedDate not supplied

Effects of ambient particulate matter and ozone on daily mortality in Rotterdam, The Netherlands.

The association between daily variations in all-cause mortality from 1983-1991 in Rotterdam, the Netherlands, and ambient air pollution was investigated. Twenty-four-hour average concentrations of total suspended particulates, Black Smoke, ozone, sulfur dioxide, and carbon monoxide were available on a daily basis. Every other day, total iron content in total suspended particulates samples was available. Poisson regression analysis was used to study associations between air pollution and mortality; generalized additive models were used to adjust for confounders (e.g., seasonal trends, weather). Daily mortality was associated most consistently with previous-day concentrations of total suspended particulates (relative risk = 1.05 for a change of 91 microg/m3) and ozone (relative risk = 1.06 for a change of 67 microg/m3). Total iron was associated less consistently with mortality than total suspended particulate mass was. The associations of mortality with ozone and total suspended particulates were independent of sulfur dioxide and carbon monoxide. The relative risks of total suspended particulates and particularly ozone were higher for subjects older than 78 y. The relationship between mortality and ozone did not deviate significantly from linear. The relationship between mortality and total suspended particulates was linear below 100 microg/m3 and leveled off at higher concentrations. If a threshold exists for the effects on mortality of these components, it exists at very low levels.

Age Factors↗

PubMedDate not supplied

Personal exposure to fine particles in children correlates closely with ambient fine particles.

To investigate the validity of ambient fine-particle concentrations as a measure of exposure in epidemiological time-series studies, we established the association between personal and ambient concentrations, within subjects, over time. We conducted repeated measurements of personal and ambient fine-particle concentrations in 13 children who lived in Wageningen, The Netherlands. For each child separately, we related personal exposures to ambient concentrations in a regression analysis. The median Pearson's correlation coefficient was 0.86. Personal fine-particle concentrations were also highly correlated with ambient particulate matter (i.e., < or = 10-microm) concentrations (median Pearson's correlation coefficient = .75). Personal fine-particle concentrations were typically approximately 11 microg/m3 higher than ambient concentrations. We excluded measurements of children who were exposed to environmental tobacco smoke, and the difference was only 5 microg/m3. The findings of high correlations between personal fine-particle concentrations and both ambient fine-particle concentrations and particulate matter (i.e., < or = 10-microm) found in this group of children provide support for investigators to use ambient particulate matter concentrations to measure exposure to fine-particle concentrations in epidemiological time-series studies.

Air Pollutants↗

PubMedDate not supplied

Personal sampling of airborne particles: method performance and data quality.

A study of personal exposure to respirable particles (PM10) and fine particles (FP) was conducted in groups of 50-70 year-old adults and primary school children in the Netherlands. Four to eight personal measurements per subject were conducted, on weekdays only. Averaging time was 24 hours. Method performance was evaluated regarding compliance, flow, weighing procedure, field blanks and co-located operation of the personal samplers with stationary methods. Furthermore, the possibility that subjects change their behavior due to the wearing of personal sampling equipment was studied by comparing time activity on days of personal sampling with time activity other weekdays. Compliance was high; 95% of the subjects who agreed to continue participating after the first measurement, successfully completed the study, and, expect for the first two days of FP sampling, over 90% of all personal measurements were successful. All pre and post sampling flow readings were within 10% of the required flow rate of 4 L/min. For PM10 precision of the gravimetric analyses was 2.8 microgram/m3 and 0.7 micrograms/m3 for filters weighted on an analytical and a micro-balance respectively. The detection limit was 10.8 micrograms/m3 and 8.6 micrograms/m3 respectively. For FP, weighing precision was 0.4 micrograms/m3 and the detection limit was 5.3 micrograms/m3. All measurements were above the detection limit. Co-located operation of the personal sampler with stationary samplers gave highly correlated concentration (R > 0.90). Outdoor PM10 concentrations measured with the personal sampler were on average 4% higher compared to a Sierra Anderson (SA) inlet and 9% higher compared to a PM10 Harvard Impactor (HI). With the FP cyclone 6% higher classroom concentrations were measured compared to a PM2.5 HI. Adults spent significantly less time outdoor (0.5 hour) and more time at home (0.9 hour) on days of personal sampling compared to other weekdays. For children no significant differences in time activity were found.

Activities of Daily Living↗