Nanoaerosols are composed of nanoparticles which may originate from different sources. Already about 10 000 natural nanoparticles per cubic centimetre of air are present even in the "pure" atmosphere of our mountains. This very high level may be enhanced by anthropogenic activities: unwanted production of nanoparticles in combustion processes called Incidental particles and Engineered particles produced intentionally in laboratories and in the industry. The detection sensitivity for engineered nanoparticles is limited by the high background noise due to Natural and Incidental nanoparticles.
Main results
- Background noise : The detection sensitivity of engineered nanoparticles is handicapped by the very high and fluctuating levels of already existing particles. Therefore the detection limit of engineered particles in conventional environments is in the 100000 – 1000000 particles/mL range! It is easier to detect engineered nanoparticles in controlled environments (clean room, portable filtering canopy, etc.)
- Measurement principles : It is necessary to standardize the chosen measurement method according to the nanoparticle types to be measured. It is often difficult to compare measurements performed with equipmentusing different principles.
- Easy-to-use equipments : A large variety of equipment can be already used to measure the nanoaerosols at workplaces. Their use is quite simple, but the interpretation of the results requires a rigorous analysis to quantify the engineered nanoparticles. It is often necessary to take into account the background noise, the specific response of the measurement tool to the engineered nanoparticles of interest, the agglomeration kinetics, etc.
- Monitoring and Sampling : Unfortunately no equipment is commercially available today for long term monitoring. Characteristics and performances of the future monitoring devices are being defined. It is possible to sample nanoparticles with an electrically conductive pipe of 20 m as long as the flow rate is greater than 10L/min.