Nucleation of jet engine oil vapours is a large source of aviation-related ultrafine particles

Abstract

Large airports are a major source of ultrafine particles, which spread across densely populated residential areas, affecting air quality and human health. Jet engine lubrication oils are detectable in aviation-related ultrafine particles, however, their role in particle formation and growth remains unclear. Here we show the volatility and new-particle-formation ability of a common synthetic jet oil, and the quantified oil fraction in ambient ultrafine particles downwind of Frankfurt International Airport, Germany. We find that the oil mass fraction is largest in the smallest particles (10-18 nm) with 21% on average. Combining ambient particle-phase concentration and volatility of the jet oil compounds, we determine a lower-limit saturation ratio larger than 1 × 105 for ultra-low volatility organic compounds. This indicates that the oil is an efficient nucleation agent. Our results demonstrate that jet oil nucleation is an important mechanism that can explain the abundant observations of high number concentrations of non-refractory ultrafine particles near airports.

Uncertainties in mitigating aviation non-CO2 emissions for climate and air quality using hydrocarbon fuels

“…One of the potential sources of particle emissions from aircra is the engine lubricating oil. [145][146][147][148] The oil is emitted through the breather vent or unintentionally as the result of worn seals. It has been suggested that UFPs may be emitted from these systems as condensable organic compounds.…”

Properties and Processing of Aviation Exhaust Aerosol at Cruise Altitude Observed from the IAGOS-CARIBIC Flying Laboratory

“…Additionally, engine lubrication oil fumes are an important source for nonvolatile ultrafine particles . Recent studies indicate that lubrication oil fumes are efficient nucleation agents, a source for volatile aerosol that will not be addressed by replacing traditional jet fuels with sustainable aviation fuels . A key difference between sulfur acid-based volatile particles and aircraft soot particles is that volatile particles can increase in size through the condensation of gaseous compounds during the early stages of the exhaust plume, whereas aviation soot particles remain almost at the same size.…”

“… 15 Recent studies indicate that lubrication oil fumes are efficient nucleation agents, a source for volatile aerosol that will not be addressed by replacing traditional jet fuels with sustainable aviation fuels. 16 A key difference between sulfur acid-based volatile particles and aircraft soot particles is that volatile particles can increase in size through the condensation of gaseous compounds during the early stages of the exhaust plume, 17 whereas aviation soot particles remain almost at the same size. Soot particles can also serve as condensation nuclei for organic species and sulfuric acid and therefore affect the nucleation and growth of volatile particles.…”

Jet aircraft lubrication oil droplets as contrail ice-forming particles

“…More recently, it has been suggested that lubrication oil droplets can effectively nucleate from the vapour phase even without a nvPM condensational sink (Ungeheuer et al, 2022). Measurements taken 30 m downstream (of the engine exit plane) of an aircraft operating at 85 % thrust have demonstrated that lubrication oil is the dominant contributor to vPM, particularly in the nucleation mode (< 30 nm) (Yu et al, 2019).…”