Musings, politics and environmental issues

Posts tagged ‘ozone’

Majority of urban dwellers subject to carcinogenic air pollution

The European Environment Agency has just released a report that is quite horrifying: around 90% of residents in the EU/EEA are exposed to one or more of the most damaging air pollutants – particulate matter and ozone (O3) – although levels of lead (Pb), sulphur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO) have decreased.  Here is an excerpt of the main findings:

Emissions of the main air pollutants in Europe declined in the period 2002–2011. This resulted in improved air quality across the region — at least with respect to certain pollutants. Certain individual sectors have seen emissions of some pollutants increase during this period. For example, PM emissions from fuel combustion in the commercial, institutional and household sector, has increased by around 7 % since 2002. This sector is now the most important contributor to total European Union PM emissions … However, due to the complex links between emissions and air quality (which include emission heights, chemical transformations, reactions to sunlight, additional natural and hemispheric contributions and the impact of weather and topography), emission reductions do not always produce a corresponding drop in atmospheric concentrations, especially for PM and O3. For example, while reductions of O3 forming substances (O3 precursor gases) have been substantial in Europe, ozone concentrations (in relation to the target value for the protection of health) have generally decreased slowly but have increased in places between 2002 and 2011.

The report goes on to explain that:

In terms of potential to harm human health, PM poses the greatest risk, as it penetrates into sensitive regions of the respiratory system and can lead to health problems and premature mortality. PM in the air has many sources and is a complex heterogeneous mixture. The sizes and chemical composition of this mixture can change in time and space, depending on emission sources and atmospheric and weather conditions.
PM in the atmosphere originates from:

  • primary particles emitted directly;
  • secondary particles produced as a result of chemical reactions involving PM forming (precursor) gases after their emission: SO2, NOX, NH3 and non-methane volatile organic compounds (NMVOC). When these gases react, they produce PM.

The size of PM is expressed in micrometers. The largest particles of concern are 10 microns in diameter or smaller (PM10). But the group of particles of most concern is 2.5 microns in diameter or smaller (PM2.5). Some of these are small enough to pass from the lung into the bloodstream … The health effects of PM are caused after their inhalation and penetration into the lungs and blood stream, leading to adverse effects in the respiratory, cardiovascular, immune, and neural systems. A fraction of ultrafine particles (with a diameter less than 0.1 microns) may even enter the brain directly through the nose.

In urban areas in the EU, 97-98% of the population is exposed to levels of ozone over WHO guidelines. With PM2.5 and PM 10, 91-96% and 85-88% of the population is exposed to levels above the WHO recommended guidelines respectively. A high proportion of the population, 76-94%, is also exposed to one of the damaging poly-aromatic hydrocarbons, benzo(a)pyrene (BaP), which is a known carcinogen.

Yesterday, just two days after the EEA report, the WHO announced that outdoor air pollution is a leading environmental cause of cancer deaths, in particular lung cancer but also bladder cancer. They evaluated PM separately and classified that too as carcinogenic. They say that the main sources of air pollution are transportation, stationary power generation, industrial and agricultural emissions, and residential heating and cooking.

The EEA also covered the effects of air pollution on climate and ecosystems.