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As BQ already mentioned they are recommended for lead based paint removal. If you have young children or pregnant adults around then look up best practice for handling the dust and paint that you have removed. It's mostly common sense but it's worth the extra care. Certainly with the lamps you get a whiff of smoke from time to time but mostly it just bubbles up and scrapes off very easly.
Are these a no-no for use on a door with old paint? Probably likely to have some lead paint in one or more layers.