Peak flow meters.
D001249:Asthma / Q000451:nursing* / Q000517:prevention & control; D002648:Child; D002669:Child Welfare; D006801:Humans; D024802:Nurse's Role; D010366:Peak Expiratory Flow Rate; D012129:Respiratory Function Tests / Q000295:instrumentation; D012572:School Health Services / Q000458:organization & administration*; D012573:School Nursing / Q000458:organization & administration*; D013147:Spirometry / Q000451:nursing*; D014481:United States