Comparison between two different nanoparticle size spectrometers.

UNLABELLED: A commercial differential mobility particle sizer (DMPS), long and medium column DMA (Grimm Aerosol Technik L-DMA model 5.400; M-DMA model 5500), condensation particle counter (CPC, Grimm Aerosol Technik 5.403), and a fast mobility particle sizer (FMPS-TSI, model 3091), were deployed to determine the size distributions of ultrafine particles. Comparisons were performed using atmospheric aerosol, as well as laboratory aerosol generated by nebulizing Milli-Q water (Millipore Corporation) and a water suspension of Fe2O3 in a Collison type atomizer. Results show that the DMPS generally measured higher particle number concentrations than the FMPS, above all for atmospheric aerosol compared to laboratory generated aerosol. With regard to size distribution, in both the atmospheric and laboratory-generated aerosols, the FMPS always showed a small peak around 10 nm, which was not shown by the M-DMPS. The agreement of the particle number concentration between the DMPS and FMPS was better in the 25-116 nm range for atmospheric aerosol, and in the 10-65 nm range for laboratory-generated aerosols. Since these instruments are scheduled to be run for air quality measurements and not only aerosol research purposes, there is an urgent need to establish working protocols in compliance with requirements with ISO 15900 requirements. IMPLICATIONS: Epidemiological studies have shown that high ultrafine particulate concentrations are associated with an increase in mortality. Measuring exposure against mass alone is not sufficient, but it is also necessary to consider exposure against number concentration. Therefore, continuous measurements of aerosol size and number concentrations are important. This paper provides a comparison between two different nanoparticle size spectrometers widely used in air quality measurements. We found significantly different total number particle concentrations and size distributions in both laboratory-generated and atmospheric aerosols. Results show that the DMPS generally measured higher particle number concentrations than the FMPS. Since these instruments are scheduled to be run for air quality measurements and not only aerosol research purposes, there is an urgent need to establish working protocols in compliance with ISO 15900 requirements.

[Epidemiologic investigation on the prevalence of goiter and urinary excretion of iodine in the school population of the province of Reggio Emilia]. / Indagine epidemiologica sulla prevalenza del gozzo e sulla escrezione urinaria di iodio nella popolazione scolastica della provincia di Reggio Emilia.

The prevalence of goiter was evaluated in a sample from the schoolchildren population of Reggio Emilia district. 1020 children underwent physical examination of thyroid gland and thyroid ultrasonography for determination of thyroid volume. Urinary iodine excretion (UIE) was measured in 837/1020 (82.1%). Iodine content was measured in water samples collected from 65 wells and 12 springs all around the district. The prevalence of goiter according to thyroid gland palpation was 26.2%. Thyroid volume was 4.74 +/- 1.87 ml, and the median UIE value 85 micrograms/l. According to the UIE classes as defined by WHO, 57.8% of all subjects showed a UIE less than 100 micrograms/l. In 57 out of 65 wells and in all the 12 springs examined, iodine was completely absent. In the remaining 8 wells, only iodine traces were found. Based on the results of physical examination of the thyroid gland, Reggio Emilia district should be regarded as an endemic goiter area. Nevertheless, thyroid volume measurement by ultrasound indicates that goiter prevalence may be markedly overestimated by palpation. The high prevalence of subjects featuring an increased thyroid volume, the low median UIE value and the poor iodine content in the local reservoirs of drinkable water suggest the opportunity for iodine prophylaxis in the Reggio Emilia district.