Aug 6, 2008
Though life has brought me close to several of the world's great catastrophes it has so far spared me involvement in any of them. We had left Czechoslovakia in 1967 a good month before the Soviet tanks rolled in and displaced Mr Dubchek. Fair go! I got out of Bangladesh in 1975 nearly a week before the military coup that overthrew the elected government and murdered the president. Likewise, although I have been accused of precipitating the first Gulf war during a visit to Syria in 1989, I was actually well out of Syria before it erupted. And while it is true that I had some technical involvement with Air New Zealand both before and after the Erebus disaster no evidence has ever been presented that would implicate me in the navigational failure which resulted in that fearful event in 1979. I only sprayed some of their aircraft to kill flies, and they did not include the ill-fated ZK NZP which crashed into Mount Erebus.
It had been known since the War in the Pacific and the work of Marshall Laird, that aircraft were potent carriers of live insects from place to place, and that they included the mosquitoes that are the carriers of malaria, dengue fever and various forms of encephalitis. More or less perfunctory attempts had been made at spraying passenger aircraft when they arrived in New Zealand from places where they might have picked up such mosquito vectors. About 1970 a dengue epidemic in the South Pacific rekindled interest in the subject, and spraying was resumed a bit more methodically than heretofor, using a World Health Organisation recommended spray based on pyrethrum. The spraying was carried out by officers of the Health Department while the arriving aircraft stood at the terminal. The procedure raised in turn, the usual whining from airlines and travel agents about the discomfort and inconvenience to passengers occasioned by the spray itself and also the five minutes' delay they had to endure while the spray circulated and the insects came in contact with it. Folk from the industrialised Northern Hemisphere can never believe that we callow antipodeans could comprehend what we are doing to them. If we do anything they are not used to it must be because we are ignorant or stupid. "We never gotten sprayed when we went to Canada." implying, I suppose, that our behaviour could not be a result of some peculiarly British idiosyncracy. The fact that any insect could, if it cared to, walk across the border between the US and Canada hadn't crossed their minds.
The airlines doubted whether the treatment was effective anyhow, and I was given the task of checking the validity of the spray regime.
At that time there was in DSIR a young fellow named Smith who had developed great skill at breeding houseflies for use as victims during the breeding of certain parasitic insects which could then be distributed at large to set about and reduce the local housefly population. (The technique was very successful, so that nowadays you can lunch outdoors in summer almost without taking flies into account., whereas in 1970 it would hardly have been worth trying). When the project was finished, Smith kept on breeding flies, more or less out of habit, I think. So when it came to testing aircraft sprays, flies seemed a good test insect to use. They are marginally harder to kill than mosquitoes so if the spray killed flies it should work on mosquitoes too. They were for us freely available, which was a consideration as there was no budget for the project. In those days, everyone including airlines expected the government to provide things for free.
We needed little containers to put flies in so we could check if the spray was killing them, and as the containers had to be free too we made them out of discarded plastic dishes that the pathologists had used for culturing fungi on agar jelly. We cut holes in the dish and its lid, and glued gauze over the holes so the flies had a little transparent cage about the size and shape of a coffee jar lid. We anaesthetised a jarful of flies with carbon dioxide from a fire extinguisher, and put about ten in each cage. By the time we got to the airport they had revived and were ready for the test. We placed cages at strategic points around the passenger cabin and got the Health blokes to spray it out.
Alas! All the flies survived and when we measured up the cabin and the amount of spray used, we found it was only about a quarter of the dose that World Health had recommended. When we tried again with the full dose you could hardly see across the cabin through the fog, and the plane smelled ominously of kerosene. Even then some of the flies survived.
The trouble was that the pyrethrum in those sprays had to be dissolved in "deodorised" kerosene before it could be used in an aerosol bomb, and the amount of kerosene in the spray, far exceeded the amount of pyrethrum. Naturally neither the airline nor the fire service nor the passengers were going to be keen on the increased dose.
Fortunately someone in England at that time had devised a synthetic form of pyrethrum that didn't need to be dissolved in kerosene, was less toxic to people than table salt, and did such a good job on insects that a very modest dose would do the job. So we tested it and it worked well. World Health also recommended it. That substance, called d-phenothrin, is still used around much of the world today, and American air hostesses are still whining about it. But at least we haven't had any more dengue epidemics spreading from island to island around the Pacific.
Of course introducing the new spray wasn't straightforward either. First we had to test it with our little cages of flies both on the ground and in flight. It worked wonderfully well, but that didn't stop the passengers complaining about the "danger" to their health, nor the airlines complaining about the costly delay on arrival while the spray circulated. Qantas claimed that it cost them $500 a minute to keep a plane on the ground when it could have been out earning money. They had talked the Australian quarantine authorities into letting the cabin crew carry out the spraying during flight, at the "top of descent". However, with the air conditioning on, the air in the cabin is completely changed every two minutes, so there wasn't much chance of the spray reaching an insect under the seat or in a luggage locker before the spray was pumped to the outside. However the air conditioning isn't used until the plane starts its takeoff run, so we thought if the cabin crew could be trained to spray as soon as the doors were shut, at "blocks away" as it is called, the spray would have time to circulate before the plane got to the start of the runway. We decided to give it a go.
Training the cabin crew wasn't difficult except that Air New Zealand in those days seemed to employ a proportion of flight stewards who were up themselves, to the extent that they arrived late for the training session and then complained that I was keeping them from their work and should "pull finger". Since I was doing the training at the airline's request I didn't like that.
So to get some assurance that the job was being done properly we insisted that we should personally monitor some flights, and that all flights should hand over the used spray cans on arrival to the agriculture quarantine officer. This didn't work particularly well either. When Ruud Kleinpaste was monitoring one flight to Sydney, he asked one of the stewardesses before takeoff, which part of the cabin she had to spray. She said she didn't know but would ask the chief steward. It then turned out that no spray cans had been brought on board, so the flight was delayed while that was remedied. On the return flight he observed from his seat, five insects in various parts of the cabin, and the spraying was so perfunctory that some of them remained alive at the end of the trip.
On one of my trips I placed a few cages of flies in strategic places and then observed the chief steward pointing them out to the guy who was to do the spraying. Even then he managed to miss some of them, perhaps because he wasted spray on drowning the ones he remembered. Only one chief steward showed enough interest to come and ask me at the end of the flight how it had gone. Unfortunately he was later killed in the Erebus crash.
So all in all I had little faith in the ability of cabin crew to do anything but hand out biscuits and sick bags, even under supervision.
But just about then a chemical company salesman came into my office to tell me about a new chemical called permethrin. If it was sprayed onto a surface, it would kill any insect that stepped on it and its effectiveness would last for a month or more. I wondered if he was pulling my leg! It looked like the answer to a maiden's prayer. Perhaps if you sprayed the inside surfaces of a plane with it, it would go on killing any mosquito that set foot on it during the next month. Its toxicity was a little more than d-phenothrin, but still less than aspirin, and I worked out that to ingest enough of it to show symptoms, you would have to lick clean the inside of a jumbo jet, upstairs and down, carpets and all.
What's more we could do the spraying when the plane was empty and on the ground for servicing, and you could get reliable agriculture quarantine staff to carry it out and issue a certificate, and the passengers and cabin crew need not know anything about it. The airline would not have to lose money while the plane stood idle on arrival either. It seemed too good to be true. We decided to try it.
But nothing is ever simple. When we tried out the permethrin on surfaces around the lab, it worked fine on windows and fabrics, but quickly lost its effectiveness on surfaces that had been painted. Fortunately aircraft are usually lined with a plastic material that doesn't need painting, and when we tested it on several versions of these plastics the permethrin worked fine. It also worked well on the fabrics used in aircraft, (curtains and seat covers), and on carpet. Furthermore, since the airlines were getting some advantage from it, they were more co-operative about giving us access to their planes for testing, even under actual operational conditions.
Back at the lab we used some pieces of lining material from various airlines to test permethrin's effectiveness against various types of insects which we confined over it under our plastic dishes. It worked well against flies, and wonderfully well against mosquitoes, which started shedding their legs almost as soon as they came in contact with it. It was a little slower, though still effective, against beetles, moths and cockroaches. It looked like we were in business.
The next thing was to try it out on actual aircraft in service. The idea was to spray the interior surfaces of the plane when it came in for maintenance, let it go on its way for a month, and then test the surfaces by caging flies against them, to see if the spray was still working. We tried it out on various domestic aircraft as well as Air Force transports and Air New Zealand international flights and it worked fine. There were some hickups, such as when the supplier of permethrin inadvertently supplied some veterinary formulation of the stuff that attacked the light fittings on an Air Force plane, and left us in bad odour with the commandant at Whenuapai. However as far as the flies were concerned it worked well, even after two months. But aircraft are supposed to get scrubbed out about once a month, so we thought they should get resprayed after each such cleaning. Air New Zealand, Qantas, Air Pacific and Polynesian Airlines were willing to adopt the method, and Aerolignas Argentinas took it up later.
After the Erebus disaster there were only two DC10's left in Air New Zealand's fleet so they got worked pretty hard, and were on the ground for maintenance for only the minimum time possible. So if you wanted to check the effectiveness of sprays on them you needed to be on your toes. Once when I entered a plane for checking I found a cleaner already at work in it, and I apologised for interrupting him. He said it was OK. "They've been working the arse off these others ever since "P" went down, referring, one supposes to the ill-fated ZK- NZP that had struck the mountain. (We were working on ZK-NZR). With that he sat himself down on the sheep skin seat covers of the first class cabin and watched me taping my transparent dishes of flies on the ceiling, walls, carpets etc. He murmured, half to himself, "An orchestrated lit'ny of flies." This was a quote from Mr Justice Mahon, who had conducted the Erebus enquiry, and had come to the conclusion that the evidence he had heard from Air New Zealand was "an orchestrated litany of lies !" , and I thought it was pretty good. But when I repeated it to the Air NZ executive officer later, he didn't seem to be impressed.
I gave a talk about the long lasting spray technique at a conference in Honiara in 1985. There was a bloke called Alec Smith there from WHO, who was sufficiently impressed to get me invited to a conference on "control of insect vectors of human diseases" in Geneva in November 1985. After that FAO adopted "residual disinsection" as a recommended practice. On the way home I stopped off in England, and visited the headquarters of Wellcome Industries who make permethrin, and they introduced me to the old guy, a Dr Elliot, who had invented it. He must have been in his seventies, but he was still alert, and I was impressed to see propped on his bookshelf, a picture of a scantily clad pin-up girl, somewhat obscured by a half bottle of gin. Life must go on.
Yet it must be recorded that in spite of the success of the technique, and the World Health Organisation's recommendation of it, United Airlines is about the only Northern Hemisphere airline that has condescended to use it. The others prefer to scatter West Nile virus, and malaria- and dengue-carrying mosquitoes wherever they go, and of course their flight crews still whinge when they get sprayed with d-phenothrin each time they bring their infested planes here.
Likewise, the German Embassy phoned me to enquire what effect our permethrin treatment would have on their tourists, and when I said it wouldn't have any effect on them, they cunningly asked how then, does it kill the insects. I had to explain that apart from a difference in size, Germans differed from insects in that the insects had their skeletons on the outside, like a crayfish, while most Germans in my experience had theirs on the inside. I refrained from explaining that if any of their tourists happened to have their skeletons on the outside, they should keep their shirts on during the flight.
However there doesn't seem to have been a serious epidemic of mosquito borne diseases in the Pacific since 1985, so we must be doing some good.