Reading through the 'Air quality in Europe - 2017 report", some questions were raised.Concerning particulate matter (PM), of course PM10 and PM2.5 are taken into account. Nowadays, everybody agrees, the smaller the particle size the more harmful particle are to human health, because of deeper penetration into the respiratory system. New air filter standard ISO 16890 already considers PM1 to valdiate efficiency of filters. Should we not start taking into account PM1, or even PM0.1 or even better, the amount of particles in the air and not the weight of particles in the air? In our opinion, the very best parameter related to particle matter, would be the reactive surface of the particle matter in the air. This is the parameter which can be expected to most closely be correlated to impact to health.
Another question concerning PM relates to natural sources, e.g. seal salt and soil erosion. Is a valid estimation at hand which amount of the PM relates to these natural sources, divded between PM10 and PM2.5? Otherwise stated: is natural PM mainly PM10, mainly PM2.5 or any other distribution?
Finally, in indoor air quality assessments, often a correlation between PM10 and PM2.5 is accepted while measuring indoor air quality. Do we also see a correlation between PM10 and PM2.5 in outdoor air quality?
To the researchers of the report at hand Alberto Gonzales Ortiz, Cristina Guerreiro, Frank de Leeuw, Anke Lükewille, Federico Antognazza, Michel Houssiau, Artur Gselia, Jan Horalek, Jaume Targa, Wim Mol, Thorne, Hai-Ying Liu, Rune Odegaard and Xavier Querol: your comments on this would be highly appreciated.
