Why is the concentration of PM10 particles in a classroom important?
Particulate Matters “10” (“PM10”) are tiny solid matters or droplets that are up to 10 micrometers large (in diameter) and can be inhaled. They circulate in air, emanating from construction sites, streets or other locations, including emerging from chemical processes. PM10 is the larger – more ‘coarse’ – type of particulate matters that tend to be studied together with PM 2.5 – the more ‘fine’ type – when looking at air quality, both indoor and outdoor. Multiple studies have found a negative impact of the presence of PM10 and PM2.5 on the neurological system and cognitive capacities, mostly for PM10 in the outdoors context but also indoors, in addition to being associated with respiratory diseases.
What amount of PM10 is right?
The World Health Organisation (WHO) Guidelines for Air Quality state that safe levels of PM10 concentration require for the concentration to be under 20 micrograms per cubic meter where exposure lasts throughout a year, and under 50 where exposure is 24 hours long. The WHO Guidelines are more careful than many others who allow for somewhat higher concentration levels.
Data from Investigation:
For the Classroom Air Quality (CAQ) study at Vienna International School, I measured PM10 concentration in a particular classroom – comparing the classroom air quality when the classroom was ventilated frequently with the situation on another day when the classroom was not ventilated.
This graph shows three things:
- Firstly, we see PM10 values to be nearly consistently below the maximum of 20 micrograms per cubic meter (set for annual exposure levels). The only exception is a time – around 12:20 – when concentration in the unventilated scenario climbed just above the threshold for just a few minutes. In relation to the 24-hour maximum – 50 micrograms per cubic meter – the levels measured are entirely unconcerning.
- Secondly, we see PM10 values decline throughout the daily measurement period. This seems to be in line with some studies undertaken of PM concentration in offices and in domestic situations suggesting that indoor PM concentration may be associated with people arriving and moving around in a room.
- Thirdly, wee see PM10 values be somewhat lower in the ventilated room – most but not all the time; in particular in the beginning of the day – when ventilation begins – the ventilated room allows for PMs to enter the room from the outside. This would be in line with the observation that most Air Quality Studies of Particulate Matters look at outdoor concentration of PMs – where more such concentrations can typically be observed. .
Indoor Air Quality 