An evaluation has been made of the health effects of a combination of fog frequency and aircraft fuel burning near the ex-Marine Corps Air Base at El Toro, CA. Data has been collected by recording the daily occurrence of local fog over a two-year time period. Meteorological conditions of air stagnation at industrial zones has caused acute health effects and deaths from environmental pollutants. The time required for such health problems to develop to toxic levels was four days or longer at sites around the globe. Killer fogs have occurred at several locations in the US and Europe, namely Denora PA, London, UK, and the Meuse Valley, Belgium. At the El Toro Airport, conditions exist that will cause the same health effects to the population living in the air shed from the landing and take-off of greater than 240 planes each day.

Major air pollution episodes from aircraft operations near El Toro, CA are predicted to occur due to a combination of geographic and meteorological conditions near the ocean on the Western shore of the American continental land mass. With the prevailing westerly winds bringing saturated air up mountain slopes and through valleys, conditions for extensive fog and high humidity are present.

Major "killer fog" episodes have occurred at several locations in the world including , Donora and Webster, PA, 6-9 October 1948 (steel mill emission of particulates, sulfur dioxide/sulfuric acid, zinc, lead and cadmium). Muese Valley, Belgium-1930 (industrial pollution from coal and coke burning), London, UK-December 5-9, 1952 (soft coal burning containing large quantities of sulfur forming sulfuric acid particulate emissions (Williamson, S.J.,1973). What is discussed here are observations of local fog conditions in Orange County, CA, combined with estimated amounts of pollutants from aircraft fuel burning during landing and take-off, reaching toxic levels (IPCC, 1999). The questions asked are:

• How often are meteorological conditions present that last long enough to cause toxicity from airplane fuel burning?;
• What times of year are the best conditions for fog pollution toxicity?
• Can we predict or model the pollution build-up during certain common environmental conditions?

To answer these questions, we must discuss the major historical events where deaths and illness occurred from pollutants at locations where conditions similar to those present at Orange County, CA exist.

"A five day period of near stagnation brought such aggravated conditions that 20 deaths occurred within a 14 hour period, when only one death might have been expected under ordinary conditions. This industrial pollution event began on October 26, 1948 due to a cold anticyclone advancing from the southwest. A cold ground intensified the elevated inversion of the anticyclone as it moved in. And then the high-pressure region stagnated over western Pennsylvania for five days until Sunday, October 31, 1948. The 1948 anticyclone moved only a few hundred kilometers, and the elevated inversion layer extended over a large portion of Pennsylvania and neighboring states. Only the inhabitants in the immediate area of Donora and Webster experienced an abnormally high rate of morbidity and mortality. Clearly, the poor ventilation was aggravated by local conditions of meteorology and industrial pollutant emissions."

One eye witness related that the fog piled up all the 26 October while the weather was raw, cloudy and dead calm and stayed that way as the fog piled up that day and the following days. It was just possible to see across the street. The extreme persistence of conditions and atmospheric stability were largely results of the peculiar terrain and micrometeorology. The slopes of the Monongahela River valley rise sharply upward to a height of 100 m to the east of Webster; on the west of the Donora, the rise is more gentle and leads to rolling hills. The bottom land thus forms a drainage basin for cold downslope winds at night, the ground-based inversions were strengthened by radiational cooling of the valley floor, and together they could produce a strong temperature inversion with a temperature gradient as high as 33 OC/km and has been measured on subsequent occasions. The fog was held close to the ground by the stability of the elevated inversion layer. During the third and fourth days of the episode, as ambient levels of pollutants escalated, almost half of the population of 14,000 people became ill. Some 43 % of the population in Donora and Webster, PA experienced some effects from the smog. The susceptibility of the group 60 years and older, 29% suffered severely. More than two-thirds of the 50 hospitalized people were over 55 years. Upper respiratory symptoms such as nasal discharge, constriction of the throat, or sore throat were experienced and, in general, the health effects were related to symptoms affected the lung (Williamson, S.J., 1973).

A documented long-term history of fog and pollutants existed for London, UK, (Brimblecombe, P., 1987). The meteorology of the city has air intruding to the London region from the Arctic that may persist for weeks if the conditions become stable or ‘blocked’. The Gulf Stream brings warm water to the Western Coasts resulting in a very moderate climate most of the year and a significant number of fog days each year. In conditions where excessive pollutants are present, the fog and large urban region could combine to court disaster, as was experienced in 1952. A four day "killer fog" occurred in London which resulted in 4000 deaths.

An episode in the Meuse Valley, Belgium occurred in 1930 when meteorological conditions led to stagnation of the overlying air and a build-up of pollutant concentrations during a week-long period. A large number of people became ill with respiratory complaints, and 60 died.

In the area of South Orange County, CA the meteorological and topographical conditions are such that a build-up of pollutant chemicals from airplanes to toxic levels may be possible. The inversion layer is stable due to low wind speed and cooling at the top of the fog layer. This layer acts as a lid to contain the pollutants generated from aircraft during take-off and landing. The key question that must be addressed is: can this inversion layer with ocean fog remain intact for a sufficient time period for build up of pollutants to toxic levels from aircraft operations?

Data has been generated by observing the daily weather pattern from the top of one of the coastal mountains, Seaview Park and Monarch Summit II from August 1999 to July 2001 (Schell, W.R., 2001). A few daily data points are missing due to observer absences from California. In relating to the pollutants at world locations, it is believed that if the inversion and fog in the local area persisted for four days or longer, pollutant build-up from aircraft fuel burning would occur in the air shed and could reach toxic levels after four days.

In defining the appropriate data, the criteria used are that four consecutive days or longer of persistent fog in the region near the El Toro Airport, would cause health effects from the build-up of high pollutant concentration. Using this criteria, the following potential "killer fog" incidents are shown in Table 1.

Date Inversion layer time Date Inversion layer time

1) September 23-28 1999 6 days Fall 1930, Meuse BE 7 days

2) January 7-12 2000 5 days October 1948, Donora, PA 4 days

3) May 2-6, 200 5 days November 1952, London, UK 4 days

4) May 19-23, 2000 5 days

5) December 1-5, 2000 5 days

6) March 25-April 2, 2001 8 days

7) May 9- 15, 2001 7 days

8) May 22-27, 2001 6 days

9) May 30-June 2, 20001 4 days

As one can see, the limited data shows that it is possible to have stable meteorological and topographical conditions that exceed the health effects limits for pollutant concentration build up from aircraft operations. These pollutants would include NOx , CO, soot particles, hydrocarbons, if the El Toro Airport were constructed. The 240 or more flights each day for four days or longer would exceed the tolerance level for health and safety of children and elderly people living in the affected region (Schell, W.R., 2001, Grigg, J., Budd, H., 2000).

There is no health reference point for the inhalation of 1014-1015 smoke particles per kg fuel burned at size range of 20-30 nm. Because of this size distribution, any inhaled particles would penetrate deep into the lungs with resultant increase in respiratory conditions in older people and children. Recent studies at Leicester University in England have shown that there is a clear link between small particles from fuel burning and respiratory disease in children. These particles may be responsible for wheeze, bronchitis and for exacerbating asthma (Grigg and Budd, 2000).

Transport of pollutant chemicals and smog from Los Angeles South into the Orange County Basin, as well as those locally generated, provides much greater chemical exposure dose to the sensitive population. The key to build-up of the concentrations of fuel by-products is the rate at which they are introduced and removed, i.e., the residence time of each constituent in the Basin. This rate of build-up from the airplane fuel burning near the airport and other sources, together with the rate of loss from all sources must be modeled. There are 18 volatile organic compounds (VOC) measured in the exhaust of jet engines used in commercial and general aviation and some of them are highly carcinogenic (Shareef, G.S.et al., 1985). Since the fuel is heavier than that of air, the net flux of much of the unburned fuel is vapor that can interact with fog droplets. In addition, the soot (smoke) particles form nucleation sites where more moisture condenses as fog. When the particles are sufficiently large, droplets form and may or may not be removed from the atmosphere because of the turbulent mixing within the inversion layer. From these data a predictive model for the future can be constructed to evaluate the concentration of all the air pollutants breathed by the inhabitants living in the air shed.

Williamson, S.J., 1973. Fundamentals of Air Pollution. Addison Wesley Publishing Co., Reading, MA, Menlo Part, CA, 472p.

Grigg, J., Budd, H., 2000. Road Pollution is Deadlier for Children. Khaleej Times, United Arab Republic. Thursday 28 December 2000.

Brimblecombe, P., 1996. Air Composition and Chemistry. Second Edition. Cambridge Environmental Series, 6. Cambridge University Press 253p.

Schell, W. R.., 2001. El Toro Airport Reuse - A Public Health Issue? In review.

IPCC, 1999. Aviation and the Global Atmosphere. A special report of the IPCC Working Groups I and III in collaboration with the Scientific Assessment Panel to the Montreal Protocol on Substances that Deplete the Ozone Layer. WMO -World Meteorological Organization and UNEP -United Nations Environmental Program. Cambridge University Press. 373p.

Shareef, G.S., Butler, W.A., Bravo, L.A., and Stockton, M. B., 1988. Air emissions species manual Vol. 1:Volatile organic species compound (VOC) species profiles. Radian Corp.1988. EPA report. 450/2-88-003a.