Passenger vehicle interior decontamination by low concentration hydrogen peroxide vapor following a wide area biological contamination incident.

AIMS: To assess low concentration hydrogen peroxide (LCHP) (H2O2) vapor dispersed with a home humidifier for its ability to decontaminate vehicle interiors contaminated with Bacillus anthracis surrogate Bacillus atrophaeus spores. METHODS AND RESULTS: Efficacy of a vaporized 3% H2O2 solution was evaluated for liquid volumes, on/off vehicle heating, ventilation, and air conditioning (HVAC) system operations, and temperatures that ranged from 5 to 27°C. Survival of the spores was assessed by quantification of remaining viable spores with efficacy quantified in terms of mean log10 reduction. Decontamination efficacy after the 6-day dwell time increased when the 3% H2O2 liquid volume was doubled, increasing from 4-of-10 to 10-of-10 nondetects (zero colonies counted using standard dilution and filter plating) inside the vehicle cabin. Recirculating cabin air through the HVAC system during decontamination decreased efficacy to 6-of-10 non-detects. While no 6-log10 reduction in viable spores was observed on the cabin filter with the cabin filter kept in place, a 6-log10 reduction was achieved after its removal and placement in the cabin during treatment. CONCLUSIONS: Results from this study allow for informed decisions on the use of LCHP vapor as an effective decontamination approach for vehicle interiors.

Medical toxicology and public health-update on research and activities at the centers for disease control and prevention and the agency for toxic substances and disease registry.

An extensive review of CDC epidemiological responses to human outbreaks of anthrax from occupational settings between the years of 1950 and 2001 documented a variety of approaches to mitigation and decontamination [2]. These approaches included taking no action, burning contaminated materials, chlorinating water supplies, instituting administrative and engineering controls and PPE, vaccinating potentially exposed individuals, and in 2 instances, fumigating with formaldehyde vapor (now considered to be a human carcinogen). Secondary contamination of a worker's home was documented in 1 case, but not felt to be clinically significant to warrant any decontamination efforts. In response to the B. anthracis attacks in 2001, chlorine dioxide fumigation, vaporous hydrogen peroxide fumigation, and a combination of HEPA vacuuming, cleaning, and bleach application were all techniques used successfully to clean B. anthracis spore contamination.

Status of worker exposure to asphalt paving fumes with the use of engineering controls.

Since 1996, industry, labor, and government have partnered to minimize workers' exposure to asphalt fumes using engineering controls. The objective of this study was to determine the use after some years of experience and to benchmark the effectiveness of the engineering controls as compared to the current exposure limits. To accomplish this objective, the current highway class pavers equipped with controls to reduce asphalt fumes, occupational exposure levels, and ventilation flow rates were monitored, and a user acceptance survey was conducted. Personal breathing-zone sampling was administered to determine concentrations of total particulate matter (TPM) and benzene soluble matter (BSM). Personal monitoring of workers yielded a BSM arithmetic mean of 0.13 mg/m3 (95% confidence limits (0.07, 0.43) mg/m3). All site average worker BSM values are below the American Conference of Governmental Industrial Hygienists (ACGIH) adopted threshold limit value (TLV) time weighted average (TWA) of 0.5 mg/m3 as benzene soluble inhalable particulate, although five sites contained 95% confidence limits slightly above the ACGIH TLV. The TPM arithmetic mean was 0.35 mg/m3 (95% confidence limits (0.27, 0.69) mg/m3). All sites showed average worker and area TPM values below NIOSH's recommended exposure limit for asphalt fumes (5 mg/m3, 15 min). One screed area sample and one operator area sample were also taken each day. Area samples followed a similar pattern to the worker breathing zone samples, but were generally slightly higher in TPM and BSM concentration. The effect of work practices and application temperatures appears to have an impact on the ability of the engineering controls to keep exposure below the TLV for BSM. To gain a better understanding of the aerodynamic properties of asphalt fumes, particle size and airborne concentrations were also monitored using a TSI model 3320 aerodynamic particle sizer spectrometer. The geometric mean particle size was between 0.64 and 0.98 micrometers for the worker breathing zone samples, with a geometric mean of 0.73 micrometers for all sites. Total airborne concentrations were typically higher for the asphalt fume exposed groups than for the background samples. During high fume events, four 15-minute samples were taken each day. Only one 15-minute sample was above the limit of quantification. Stack flow rates were measured, and results are discussed and compared to the manufacturers' nominal values. Survey results were generally positive, with recommendations discussed for continuous improvement.