Figure 1 . Classification of Particulate Matter PM10 – thoracic Particulate Matter, particles with a diameter <10 μm (micron) in size, that can be stopped as they enter the throat. Examples: pollen, desert dust, beach sand and human hair. PM2.5 – fine thoracic Particulate Matter, particles with a diameter <2.5 μm in size, that may be filtered by the lungs and alveoli. Examples: pollen, mold spores and toner dust. PM1 – sub-micrometre Particulate Matter, particles with a diameter <1 μm in size that can remain in the atmosphere for weeks. When inhaled, PM1 particles travel to the deepest area of the lungs, where a significant part of them enter the bloodstream, damage the inner walls of arteries, penetrate tissues in the cardiovascular system and potentially spread to organs. Examples: nanoparticles, exhaust gasses and viruses. Human hair 50-70µm PM1 < 1µm ach d m PM10 < 10µm PM2,5 < 2.5µm PM10 PM2.5 PM1 <10µm <0.01mm <2.5µm <0.0025mm <1µm <0.001mm icles are stopped when they enter the throat. ticles are stopped in the lungs and alveoli. cles travel to the deepest parts of the lungs. PM10 PM2.5 PM1 <10 μm <0.01 mm <2.5 μm <0.0025 mm <1 μm <0.001 mm 6 Whitepaper: Enhanced Indoor Air Quality for Office Buildings Role of Particulate Matter Particulate Matter (PM) is an air pollutant produced by a combination of suspended solid and liquid particles in the air. It can either be emitted directly into the air by vehicles, trucks or heavy machinery (called primary PM) or formed by Sulfur Dioxide, Nitrogen Oxides or Ammonia (called secondary PM)6 (WHO, 2006) in the atmosphere. Such airborne particle concentrations are used as key quality indicators of indoor environments. Scientific evidence shows that exposure to fine particles can cause adverse cardiovascular effects, including heart attacks and strokes resulting in hospitalisations and, in some cases, premature death7 (U.S. EPA, 2007). A number of studies have also linked exposure to fine particle to respiratory issues, including the exacerbation of asthma (short-term exposure) and the impairment of lung development (long-term exposure)7 (U.S. EPA, 2007). The common technical classification of fine PM is based on particle sizes, according to the areas where they are deposited in the human respiratory system (figure 1). Leading health organisations classify PM10, PM2.5 and PM 1 fine dust fractions as dangerous and harmful for humans8 (EEA, 2019). Today, concentrations of PM continue to exceed set limit values in Europe. In 2017, 44 % of EU-28 urban population was exposed to PM10 concentrations exceeding the WHO air quality guideline value. In 2016, long term exposure to PM2.5 concentrations resulted in about 412,000 premature deaths in Europe alone8. 6 Source: WHO (2006), ‘Health risks of particulate matter from long-range transboundary air pollution’, World Health Organisation. 7 Source: U.S. EPA (2007), ‘Particulate Matter Concentrations’, United Status Environmental Protection Agency. 8 Source: EEA (2019), ‘Air quality in Europe - 2019 report’, European Environment Agency. For PM2.5, approximately 77 % of the population was exposed to concentrations exceeding the guideline. Estimates indicate that PM2.5 concentrations in 2016 were responsible for about 412,000 premature deaths originating from long term exposure in Europe8 (EEA, 2019).