Sulphur dioxide - The level of pollution of the territory of Prague by sulphur dioxide in 1997 is characterized by yearly arithmetic means and 95% quantils of sulphur dioxide concentrations presented in maps. Yearly mean concentrations ranging from 20 to 30 µg.m^-3 account for the largest part of the territory of Prague (70.5 %). For 57.6 % of this territory the value of the 95% quantil of the year set of daily means falls into the 80 to 120 µg.m^-3 interval. A relatively higher pollution in excess of 30 µg.m^-3 of yearly arithmetic mean was registered in the centre of Prague, especially in the first and second districts. In 1997, none of the monitoring stations exceeded the imission limit. Except for the Prague 1 Monitoring station (Námestí Republiky) the yearly arithmetic mean of all the monitoring stations in the territory of Prague was below one half of the imission limit. Compared to 1996 the year 1997 showed a substantial decrease of sulphur dioxide pollution as a result of favorable weather and dispersion conditions .

 Sulphur dioxide - yearly arithmetic means of concentrations, Prague 1997
Sulphur dioxide - 95% quantils of daily concentrations, Prague 1997

Suspended particulate matter - The level of pollution of the territory of Prague by suspended particulate matter in 1997 is characterized by yearly arithmetic means and 95% quantils of suspended particulate matter and PM₁₀ fraction concentrations presented in maps. Yearly mean concentrations ranging between 40 and 50 µg.m^-3 account for the largest part of the territory of Prague (54.4 %). The centre of Prague is, insofar as the measured concentrations of suspended particulate matter are concerned, the second worst district of the Czech Republic. In 1997 the highest concentrations were measured by the monitoring stations Svornosti (Prague 5), and Sokolovská (Prague 8), where applicable imission limits were dramatically exceeded. A high PM₁₀ fraction pollution was registered by the Námestí Republiky (Prague 1), Mlynárka (PM₁₀ - Prague 5), and Vršovice (Prague 10) monitoring stations. However, compared to 1996 there was a reduction in the pollution by suspended particulate matter as a result of favourable weather and dispersion conditions like in the previous case of sulphur dioxide.

 Suspended particulate matter - yearly arithmetic means of concentrations, Prague 1997 
Suspended particulate matter - 95% quantils of daily concentrations, Prague 1997  

Nitrogen oxides - Yearly arithmetic means and 95% quantils of NO_x concentrations shown in maps are used to characterize the different monitoring points in Prague in 1997. Prague and especially its central part shows the highest concentrations of nitrogen oxides in the Czech Republic, with a slightly growing trend due to increasingly denser traffic through the City centre. In 1997, all the monitoring stations in Prague, except for one, registered values exceeding the daily limit in more than 5 % of cases. The yearly imission limit was exceeded at eight stations. Extreme pollution levels in 1997 were recorded by the Public Health Office monitoring stations Svornosti (Prague 5), and Sokolovská (Prague 8), where NO_x concentrations were more than twice the imission limit. A high number of cases in which the imission limit was exceeded was also recorded by the AMS CHMÚ stations in Mlynárka (Prague 5), Námestí Republiky (Prague 1), and Vršovice (Prague 10). Compared to 1996 there was a slight increase in the NO_x pollution.

 Nitrogen oxides - yearly arithmetic means of concentrations, Prague 1997
Nitrogen oxides - 95% quantils of daily concentrations, Prague 1997

Tropospheric ozone - Near-ground ozone concentrations have been monitored by the AIM network since 1992. In 1997 there were five stations operating in the territory of Prague. The peak eight-hour concentration was 158 µg.m^-3 and was recorded by the Libuš station (representing the urban background) on August 27, 1997 (the eight-hour imission limit is 160 158 µg.m^-3). The highest eight-hour average concentration 191 µg.m^-3 was recorded by the same station on the same day (the special hourly imission limit is 180 µg.m^-3). Instances in which the ozone imission limits are exceeding are often of a fleeting nature with high concentrations observed over a few successive days during which weather conditions favor the formation of ozone (intensive solar radiation, high temperatures). The weather conditions in the summer of 1997 did not favor the formation of tropospheric ozone, and the measured concentrations were therefore relatively low.

Carbon monoxide - Carbon monoxide concentrations have been monitored by the Automatic Imission Monitoring System since 1993. In 1997 there were nine monitoring stations in the territory of Prague. Like in previous years CO imission limits, i.e. the 24-hour limit (IH_d, i.e. 5,000 µg.m^-3) and the half-hour limit (IH_k, i.e. 10,000 µg.m^-3), were exceeded very exceptionally in 1997. Compared to the other atmospheric pollutants, carbon monoxide thus remains the least problematic substance in Prague.