Ambient nano and ultrafine particles from motor vehicle emissions: Characteristics, ambient processing and implications on human exposure

Exposure of Children to Ultrafine Particles in Primary Schools in Portugal

“…The type of the outdoor environment may also exert influence on the potential UFP levels. Morawska et al (2008) compared UFP number concentrations across a wide range of environments (71 studies ranging from clean places to tunnels). Specifically for urban sites, estimated means between 7.2x10 3 and 10.7x10 3 pt/cm 3 (based on 24 studies) were found, similar to our present study.…”

Prediction of ultrafine particle number concentrations in urban environments by means of Gaussian process regression based on measurements of oxides of nitrogen

“…This work focuses on UFP with size larger than 25nm. Smaller particles in the nucleation mode are volatile and unstable in nature, and it is challenging to accurately measure them (Morawska et al, 2008). This is also one of the reasons why particles below ∼25nm are not part of current Euro 5/6 vehicle emission standards.…”

“…In terms of size ranges, the nucleation, Aitken and accumulation modes typically encompass 1-30, 20-100 and 30-300nm, respectively. Particles with a diameter below 30nm contain nearly 30% of total PNC (Morawska et al, 2008;Kumar et al, 2010).…”

“…UFP are commonly defined as particles having a diameter of less than 100nm (Morawska et al, 1998), and the consensus is that these particles contribute most (around 80%) to the total particle number concentration (PNC) (Heal et al, 2012;Kumar et al, 2011c;Morawska et al, 2008;Charron and Harrison, 2003), whereas their corresponding mass accounts for less than 20% of the total particle mass concentration (Kittelson, 1998). UFP can be classified into the "nucleation", "Aitken" and "accumulation" modes.…”

A study of water-soluble inorganic ions in size-segregated aerosols in atmospheric pollution episode

“…Recently, major water-soluble inorganic ions in urban areas have shown a significant fraction of fine and ultrafine sulfate and nitrate (Lin et al 2007). The increase of the diesel vehicular fleet along with the type of fuels used in combustion process could be one of the reasons for the observed increase in ultrafine concentrations of these species (Maricq 2007;Morawska et al 2008). This growth is important from a health perspective because the ultrafine particles can have a much stronger physiological effect than coarse particles (Donaldson et al 1998;Wichmann et al 2000).…”