This indicator is in three parts: 1. The number of days per year when air pollution from PM10 is moderate or high. Moderate or high PM10 concentrations are those above 50µg/m3 (the Expert Panel on Air Quality Standards (EPAQS) standard level). 2. The number of days per year when air pollution from ozone is moderate or higher. Moderate or high ozone concentrations are those above 100µg/m3 (the EPAQS standard level). 3. The average annual nitrogen dioxide concentration.
The major threat to clean air is now posed by traffic emissions. Petrol and diesel-engine motor vehicles emit a wide variety of pollutants, principally carbon monoxide (CO), oxides of nitrogen (NOx), volatile organic compounds (VOCs) and particulates (PM10), which have an increasing impact on urban air quality. In addition, photochemical reactions resulting from the action of sunlight on nitrogen dioxide (NO2) and VOCs from vehicles leads to the formation of ozone, a secondary long-range pollutant, which impacts in rural areas often far from the original emission site. Acid rain is another long-range pollutant influenced by vehicle NOx emissions. In all except worst-case situations, industrial and domestic pollutant sources, together with their impact on air quality, tend to be steady-state or improving over time. However, traffic pollution problems are worsening world-wide. According to the National Air Quality Archive the health effects of the pollutants measured in this indicator are: o Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as influenza. Continued or frequent exposure to concentrations that are typically much higher than those normally found in the ambient air may cause increased incidence of acute respiratory illness in children; o Fine particles can be carried deep into the lungs where they can cause inflammation and a worsening of the condition of people with heart and lung diseases. In addition, they may carry surface-absorbed carcinogenic compounds into the lungs; o Ozone irritates the airways of the lungs, increasing the symptoms of those suffering from asthma and lung diseases. In addition, a government report in 1997 found a clear relationship between deprivation and NO2 and PM10 levels. It concluded that policies focused on areas of high pollution could marginally reduce the apparent disadvantage of deprived communities in terms of air pollution.
Legacy unique identifier: P01102