The problems of mass catering for holidaymakers are often intensified in the less developed countries which have the climate, scenery, and local rural customs that attract tourists from colder, industrialized, and urbanized countries. Mass tourism is an excellent method of earning foreign currency, and most countries are eager to capitalize on it - sometimes at the expense of maintaining adequate health care provisions. A rapid development of tourist hotels may create a strain on local sanitation facilities, causing visitor health problems by polluted bathing or drinking water; there is often a lack of knowledge locally of the technology of mass catering, and perhaps a shortage of semi-skilled workers; and hygiene habits of the workforce may be unsatisfactory and lead to illness. In addition, in an apparently modern hotel, tourists may not take the precautions they would normally take when visiting a foreign country. They may drink unboiled milk in the belief that it is pasteurized; eat fruit and salads under the impression that they have been washed in clean water by clean hands; may overlook that the ice cubes in their drinks may have been made from tap water; and may forget that in many developing countries it is not the custom to store meats under refrigeration.