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Study finds airplane traffic a major contributor to particle pollution in Los Angeles

Spatial pattern of PN concentration. Inset shows wind direction. Credit: ACS, Hudda et al. Click to enlarge.

Results of a new study suggest that emissions particle emissions from airplane traffic at Los Angeles International Airport (LAX) are a major source of particle number (PN) concentrations in the Los Angeles area that are of the same general magnitude as the entire urban freeway network. The results also indicate that the air quality impact areas of major airports may have been seriously underestimated.

The study by a team from the University of Southern California and the University of Washington, published in the ACS journal Environmental Science & Technology, measured the spatial pattern of particle number (PN) concentrations downwind from the Los Angeles International Airport (LAX) with an instrumented vehicle (a gasoline hybrid) that enabled coverage of larger areas than allowed by traditional stationary measurements.

Scott Fruin, Neelakshi Hudda and colleagues noted that past research has measured pollution from air traffic before, but most of these studies only sampled air within a couple of miles, at most, from airports.

Over a period of 29 days, the scientists measured at least a 2-fold increase in PN concentrations over unimpacted baseline PN concentrations during most hours of the day in an area of about 60 km2 (23 square miles) that extended to 16 km (10 miles) downwind and a 4- to 5-fold increase to 8−10 km (5−6 miles) downwind.

The maximum PN concentrations were aligned to eastern, downwind jet trajectories during prevailing westerly winds and to 8 km downwind concentrations exceeded 75,000 particles/cm3—more than the average freeway PN concentration in Los Angeles.

During infrequent northerly winds, the impact area remained large but shifted to south of the airport. They calculated that the freeway length that would cause an equivalent impact to that measured in this study (i.e., PN concentration increases weighted by the area impacted) was 280−790 km (174-491 miles). The total freeway length in Los Angeles is 1500 km (932 miles).

Based on their calculations, the scientists concluded that within the area they found to have elevated pollution from the airport, automobiles contributed less than 5% of the PN levels.

The emissions from LAX are likely not unique on a per-activity basis. The large area of impact from LAX suggests that air pollution studies involving PN, localized roadway impacts, or other sources whose impacts are in the influence zone of a large airport should carefully consider wind conditions and whether measurements are influenced by airport emissions.

Source apportionment of specific airport sources or activities was beyond the scope of our study but would be necessary to evaluate the effectiveness of possible mitigation options. Differing NO2 to NOx ratios at different levels of engine thrust20 might be used to distinguish the contributions of jet landing, idling or takeoff activities. Takeoff and idling emission also differ in surface properties (i.e., the ratio of active surface area to surface bound photoionizable species) and particle size distributions differ between aircraft and ground support equipment emissions.

—Hudda et al.


  • Neelakshi Hudda, Tim Gould, Kris Hartin, Timothy V. Larson, and Scott A. Fruin (2014) “Emissions from an International Airport Increase Particle Number Concentrations 4-fold at 10 km Downwind,” Environmental Science & Technology doi: 10.1021/es5001566



One should not live in take-off and landing paths of major airports, at least for the first 20 Km, to avoid both noise and air pollution.


Well, what do you know? Someone finally spilled the beans on aircraft pollution. Seems it's been a dirty secret for a long time and well covered up by the stakeholders, including the Federal Government.


"Seems it's been a dirty secret for a long time and well covered up by the stakeholders, including the Federal Government"

Not really. The EPA has forced a replacement for 100LL for general aviation piston engine aircraft. This was initiated more than 5 years ago. High octane substitutes have recently been developed by a number of companies most notably Shell Oil.


"the air quality impact areas of major airports may have been seriously underestimated."
Also, we are talking jets here, not leaded fuel. Scientists have known about the pollution of jet aircraft for many years. It's one of those issues you can't do much about without impacting the commercial air travel business. So, people have really not seriously addressed the problem head on. With one exception; Brown's California high speed train is a step in the right direction by replacing intermediate air travel with high speed train travel.


It is hardly a surprising discovery. Jet engines use diffusion combustion, just like diesel engines, but I see no DPFs on the airplanes. In diffusion combustion, basically all particles are below 1 micrometer (as in piston engine exhaust). Thus, the contribution to PM10 and PM2.5 is very small. Since many years, US EPA has focussed on the larger particles and completely ignores PN. To give you a perspective, 75 000 particles/cm3 is about 10x the level I have in my office and in my home (these are my own measurements). This is also approximately the ambient level in the rural area where I live. I have no airports close but ~2 km to a freeway.


This report makes sense. It would also be interesting to know the particulate levels and areas affected by truck traffic and also train traffic. I lived in Vancouver washington for about 20 years, near the interstate and also near the 20+ trains that passed daily.

Roger Pham

Perhaps this is a strong argument for development of regional transports using electric trains, perhaps high speed train for trips under 1,000 miles. The experiences of the French and Chinese would be very valuable for development of American version.

Perhaps with continual development of molten air batteries, electric flights will be possible for regional transportation that will be more economical and non-polluting, reserving petroleum fuel only for long-distance flights. Electric propulsion and with Google autopilot and Google map will enable direct point-to-point personal air travel from tens of thousands small airports that will avoid the hassle of airline flying altogether. Electric propulsion and Google autopilot will make it even less expensive in comparison to even airline flying today.



I fully agree with you on the use of very high speed e-trains for 1,000 miles or even more. They are more efficient and just as fast. Those 350+ kph e-trains are a success story in France, China, Japan and many EU countries.

In the not too distant future, improved batteries and probably improved FCs will power electrified airplanes, starting with small units and gradually to mid size units. It could solve the noise and air pollution current problem in airport areas.

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