Flag 199 - Local interference, flag used by the CHMI network
Flag 559 - Unspecified contamination or local interference; considered valid, however
Flag 652 - Construction acitivity nearby

¹ Probable occurrence of dust from the Sahara desert (potentially influenced samples from 22.–25. 5. 2014). Applies to most localities in the Czech Republic.

² At the locality Praha-Libuš, the filter was irregularly contaminated by insects during the course of 2014.

³ In July and August 2014 (27. 6 – 25. 8., source: Brněnské komunikace a.s. company) road works took place in the immediate vicinity of the Brno-Úvoz station (hot spot), which caused a large number of overlimit values especially in July; the maximum daily concentrations reached 109 µg.m-3, which is highly unusual for July. The July value (46.2 µg.m-3) is unusually high also from the perspective of average monthly concentrations; in July (during grinding works) concentrations were strongly above the long-term average.

⁴ Wood was being burned (as part of forest maintenance) in the surroundings of the Košetice station in January and March 2014; agricultural activities (machine lawn mowing, agricultural activities, spraying of chemicals) took place from April to October; the surface of the nearby road was repaired at the end of September.

⁵ Tanvald station – increased amount of pollen on the filter at the turn of April and May of 2014.

⁶ At the Brušperk measuring locality, from the middle of May until the beginning of October 2014, construction works associated with thermal upgrades of surrounding buildings took place. In isolated cases, these works might have locally influenced monitored values and potentially caused partial overvaluation of measured concentrations in the warm half of the year.

⁷ From 19. 8. until 15. 9. 2014 at the Ostrava-Přívoz station, earth moving works took place in the surroundings – new playground surface, excavation.

⁸ Local interference with measurements occurred irregularly in Ostrava-Zábřeh during 2014 due to the construction of a link between adjoining roads.

⁹ It was confirmed that measurements at the locality Krupka and in its surroundings were influenced by a local source. This was supported also by concentration roses from measurements made at the Krupka station. The local source was the heating system of house number 456, owned by the town of Krupka, in the district of Krupka Martinka, On 8. 4. 2014 the town council decided to solve the problem by replacing the current solid fuel boiler with a new one belonging to the 3rd emission category. The boiler was due to be replaced before the start of the new heating season – i.e. before 30. 9. 2014. After the boiler was replaced, CHMI staff ascertained during the winter season of 2014–2015 that high values of average hourly concentrations no longer occurred in late afternoon hours (see Annex III. Concentration roses).

¹⁰ Lom – the exposed filter was taken for repair together with the device. Contamination therefore cannot be ruled out (10. and 12. 2. 2014).