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Respiratory Illness Associated with Carpet Cleaning at a Hospital Clinic -- Virginia

On November 8, 1982, eight (47%) of 17 employees on one floor of a hospital clinic had cough and throat irritation after entering their work environment. Symptoms disappeared that day when windows were opened or when workers left the building. Inspection of the building and its heating and air conditioning systems by an industrial hygienist failed to uncover any obvious source of chemical or carbon monoxide exposure. Recommendations were made to improve ventilation, but work-related symptoms continued until November 25. Three employees who saw physicians had sore throats of unknown etiology.

Carpeting on that floor had been shampooed the weekend before earliest onset of illness. Employees on another floor had experienced a similar illness after carpet cleaning the previous weekend.

To better define the illness and the factors responsible for it, 48 questionnaires were distributed on December 21 to employees on four floors of the building. Any employee who experienced a work-related symptom was considered a case. Twenty (42%) questionnaires were returned. Thirteen (65%) respondents gave a history of work-related symptoms. The most frequently experienced symptoms were cough (76%), headache (53%), sore throat (53%), awareness of an unusual odor (46%), shortness of breath (31%), nausea (23%), other gastrointestinal symptoms (23%), and fatigue (23%). Symptoms lasted from 2 to 17 days (median 5 days). Employees working in carpeted areas were more likely to develop symptoms than those working in uncarpeted areas (12/14 compared with 1/6, p = 0.01). No other risk factors were identified.

Given the temporal and physical association between illness and recently cleaned carpets, the cause of illness was suspected to be dried carpet shampoo aerosolized by employees walking on the carpets. The active ingredient of this shampoo was sodium dodecylsulfate (sodium lauryl sulfate). This type of shampoo had not previously been used in that building. The manufacturer states that "overuse of this superconcentrated product can cause an irritating powder to be formed after drying." Although underdilution of the shampoo concentrate and inadequate vacuuming of the carpet containing dried shampoo were suspected as responsible for the outbreak, neither could be confirmed.

A possible contributing cause was a relative lack of fresh-air ventilation in the building. On December 7, 7-hour air samples for dust analysis were obtained on one of the involved floors using a model "G" MSA air pump with a FWSB filter*. At floor level, the dust concentration was 0.016 mg/m((3)) of air. The dust contained a total of 6.5 ug sulfate or 56% of the total weight. At breathing level, the measurements were: dust--0.076 mg/m((3)); sulfate--5.2 ug or 8% of total weight. Control samples were obtained from two other buildings--one with new carpeting, the other with no carpeting; both contained less than 0.5 ug of sulfate.

Ongoing surveillance revealed no new cases after thorough vacuuming and steam cleaning of the carpets. Reported by VA Lamb, Epidemiology Unit, RF Walter, Environmental Health and Safety, Medical College of Virginia, CW Armstrong, MD, B Schofield, K Wasti, PhD, Div of Health Hazards Control, G Miller, Jr, MD, State Epidemiologist, Virginia State Dept of Health; Hazard Evaluation and Technical Assistance Br, Div of Surveillance, Hazard Evaluation, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: The prevalences of the various symptoms reported here are similar to those reported in two previously published outbreaks (1), except that eye irritation (50%-60% in the previous outbreaks) and sneezing and nasal congestion (30%-40%) were not mentioned in this outbreak, and gastrointestinal symptoms, except nausea, did not occur in the other outbreaks. The reported respiratory symptoms are not specific for sodium dodecylsulfate, but are common to numerous irritant particulates, aerosols, and gases. Nevertheless, the temporal association between use of carpet shampoo and the outbreak, and the absence of further cases after vacuuming and steam cleaning the carpet, tend to implicate carpet-shampoo residue as the etiologic agent.

As in the previous outbreaks, under-dilution of shampoo concentrate was the suspected reason for shampoo residue remaining in the carpet. Since commercial cleaning products may contain a variety of irritating or potentially toxic compounds (e.g., sodium carbonate, sodium perborate, sodium phosphates, ammonium compounds, borax, pine oil, trichlorethylene, perchloroethylene, naphtha, naphthalene, kerosene, petroleum solvents, alkyl benzene sulfonate, alkyl aryl sodium sulfonate) (2), concentrates should be fully diluted before use according to manufacturers' directions, and all such products, especially "heavy-duty" or "industrial strength" varieties, should be used only where there is adequate ventilation.


  1. Kreiss K, Gonzales MG, Conright KL, Scheere AR. Respiratory irritation due to carpet shampoo: two outbreaks. Environ International 1982:8:337-41.

  2. Gosselin RE, Hodge CH, Smith RP, Gleason MN. Clinical toxicology of commercial products. 4th ed. Baltimore: Williams & Wilkins, 1976.

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