Abstract
show that the radiological impact of this event at Hungarian locations has been of no considerable concern.

and Sinclair et al. [3] reported on the occurrence of radioxenon isotopes on the west coast of USA and Canada, respectively, as early as 16

March 2011, while Diaz Leon et al. [4] and Norman et al. [5] reported on the presence of radioiodine, radiothallium and radiocaesium isotopes in aerosol and rainwater samples, respectively, on the west coast of USA as early as 18 March. and from fallout have also been performed for adults.
Experimental

Sampling
Aerosol samples have been taken at the following locations ( Fig. 1) At Paks NPP monitoring stations, aerosol samplers also contain elemental iodine and organic iodide traps, sequentially after the aerosol filter plates. These are collecting on silver impregnated activated charcoal filter plates (Kalman System Ltd., Hungary) and on NUCLEARCARB 207B 5TEDA (CHEMVIRON CARBON, Belgium) activated charcoal filter cartridges, respectively, with the same effective diameter as the aerosol filter.
Measurement
Gamma-spectrometry measurements have been carried out either at ATOMKI for All activity data have been decay-corrected in two steps: using the 'decay during sampling' model (implementing the well-known differential equation used for the same purpose e.g. in radon studies) of the gamma-spectrometry software to the end of the collection period and then to the median of the collection period using simple decay calculation.
Results and discussion

Distribution of 131 I in aerosol samples
Temporal variation of activity concentration of 131 I (in µBq/m 3 ) in aerosol samples from all sampling locations is shown in Fig. 2 (1σ uncertainties included) . The temporal scope of data points are defined by horizontal error bars.
Distribution of 131 I in aerosol samples
One As it can be seen, the data points from Paks NPP are longer term (usually 3-8 days) averages with regular sampling, while the data points from other places (especially from ATOMKI) provide information on narrower time intervals (typically 6-18 hours)
Distribution of 131 I in aerosol samples
with less uniform pattern. The former sampling pattern provides lower detection limits and counting uncertainties but is less responsive to changes while the latter is more responsive to changes but usually possess higher detection limits and counting uncertainties. The combination of these two sampling patterns can provide as much information as a uniform daily (e.g. [6]) or 2-days-long sampling (e.g. [9] ). Although the average distance between the sampling points is about 200 km, the differences between concentrations detected at the same time for different places are always within a factor of 2. respectively. That is, the atmospheric removal of these forms is a bit slower than that of particulate form. A possible explanation to this is that these forms are subjected to dry deposition significantly less than that of aerosol form. where τ137,a is the effective decay constant for particulate 137 Cs, while τx is either τ131,a (for particulate 131 I) or τ134,a (for particulate 134 Cs), depending on the ratio in question.
Distribution of organic-and elemental-
From the fitting of the 131 I/ 137 Cs ratio (see dashed line in Fig. 4 ), using the previously determined τ131,a value, we obtained a τ137,a value of 0.086±0. By mixed fallout sample we understand that the dry fallout sample of a given period had not been collected before the next rainfall event occurred. That is, more or less wet fallout was mixed to these samples.
Distribution of organic-and elemental-
As one can expect, the flux density of dry fallout samples have been at least one order of magnitude lower than that of wet ones. For dry fallout, with the assumption that only the aerosol form 131 I was subjected to deposition, and with deposition velocity defined as the quotient of flux density (in µBq/m 2 ·d) and of concentration (in µBq/m 3 )
Distribution of organic-and elemental-
the average daily dry deposition velocity has been calculated as shown in No. 115 [12] . Results are summarized in Table 2 . As one can observe, the contribution from the inhalation of organic 131 I is the most prominent, due to its increased biological effectiveness and highest concentration among the three 131 I forms studied.
Distribution of organic-and elemental-
Additionally, a location-specific effective external dose-rate contribution from 131 I fallout at ATOMKI has been calculated for adults, assuming 1 m distance from soil surface (data taken from Fig. 5 ). The contribution from this source is estimated to have been about 0.02 nSv/10% outdoor time for the observation period. That is, it has been only 1% of the previous samanthaholloway@example.org.
Conclusions
Due to the large distance between source and deposition area, only traces of the emissions from Fukushima were detectable in Hungary. Dose contribution from airborne and fallout isotopes is estimated to be 18 nSv for adult population at maximum for the observation period (6 weeks). In comparison, dose contribution in the vicinity of Paks NPP from its normal operation is about 45 nSv/year, i.e. 5 nSv for the same 6-week period.
Conclusions
Consequently, the radiological impact of this event at Hungarian locations has been of no considerable concern. 

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