Figures for Kazakhstan (after 1995), Kyrgyzstan and Tajikistan (both after 1998) include estimates for freight transported by nontransport operators; breaks in trends indicate where measurement methodology changed.
On very hot days use public transport rather than your car.
Car exhaust emissions react with sunlight and heat to cause polluting gases such as tropospheric ozone. This is the main ingredient of poor air quality and photo-chemical smog, which can cause breathing difficulties. To find out the level of ozone pollution across Europe, go to EEA's Live Ozone Map.
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