Comparison of the Effort Required for Screening Important Targets in Great Britain with that Involved in Throwing a Smoke Screen over the English Channel. Memo. By Meterological Office and Ministry of Home Security

4. A large scale trial was carried out on behalf of the Home Office about two years ago in which a smoke screen was generated along a 4-mile front. To maintain the cloud for half an hour cost about €7,000 for smoke material. The screen was reasonably effective for a distance down wind of about 20 miles, but if it had been desired to produce a cloud only 4 miles long it would not have been possible to make any great reduction in the amount of smoke material to be used. The weight of the smoke generators required for this half-hour trial was about 30 tons.