Analytics: Air quality information

The Air Quality Index for Health is provided by the Irish Government’s Environmental Protection Agency. This gives an idea of how harmful pollution is at different levels on a scale from 1 to 10. 1-3 are good, 4-6 are fair, 7-9 are poor and 10 is very poor. Further information is available at https://airquality.ie/information/air-quality-index-for-health.

PM2.5 means all the dust in the air that’s smaller than 2.5 micrometers. That’s 1/50th the width of a human hair. When you breathe this dust in, it travels deep into your lungs and can damage them. It can also cross into your blood which can cause problems with your heart. PM2.5 comes from lots of places. Some natural sources include dust from the desert, salt that evaporates from the sea, and volcanic eruptions. But there are many human-made sources too, such as cars, wood, coal or peat fires and some kinds of industry.

The AQIH for PM2.5 is determined by a rolling mean over 24 hours.

PM10 is all the dust smaller than 10 micrometers. Like PM2.5, it can cause problems when you breathe it in. But lots of the larger dust can get stuck in your throat and windpipe instead of making it to the lungs, so it’s less harmful.

The AQIH for PM10 is determined by a rolling mean over 24 hours.

NO₂ is a gas made when things burn. Indoors, it can come from gas hobs and other places there are fires. Outside, it’s mostly caused by cars, buses and lorries that still use petrol or diesel (not electric cars) as well as some power stations. NO₂ can affect your throat when you breathe it in, making you more likely to have an asthma attack or get COPD in the long term.

The AQIH for NO₂ is determined by the mean over one hour of readings.

O₃ is made out of oxygen. It is made naturally in the atmosphere by the sun’s rays interacting with the air (creating the ozone layer). Normally it’s found high above the Earth (12-50km up). However, sometimes other pollutants mean O₃ can form at ground level, where it causes health problems, particularly for children and elderly people. O₃ can also be transported around the world and create high levels far away from where it was created. Because of the complicated chemistry involved, O₃ is worse in rural areas than urban ones.

The AQIH for O₃ is determined by a rolling mean over eight hours.

SO2 is made when things are burned. It’s very often made when people burn coal, oil or wood to heat homes, particularly in rural areas, or by coal or oil power plants. SO2 was one of the main causes of acid rain. Because of the introduction of so-called “smokeless” coal and falls in the use of coal and oil to make electricity, levels have been falling in Ireland for some years.

The AQIH for SO₂ is determined from the mean over one hour of readings.