A usability assessment of riding lawn-mowing equipment with varying levels of design standards compliance.

The use of riding lawn equipment (RLE) is related to a significant number of accidents every year. To provide basis for product design and enhance user performance and safety, a usability and performance assessment of modern riding lawn-mowing tractor designs and features was conducted in a real-world test environment. Five current commercially available RLEs were tested with response measures including task performance time and accuracy, physiological workload, system usability scores (SUS), and subjective rankings of RLE models. This data was used to identify sensitivity of responses to variations in RLE design features and functionality. The data was also used to assess the validity of new tractor design standard conformance tool, the RLEval methodology. This tool made comprehensive evaluation of RLE models compliance with over 70 specific design standards and was applied by human factors experts. Experiment results revealed sensitivity of all response measures to design differences among the five RLE models, except the objective workload measures. Response measures including task performance, SUSs and subjective rankings showed partial agreement with the RLEval scores. In general, the study results demonstrated a comprehensive experimental methodology for usability and performance evaluations of RLEs as well as merit of using the RLEval as preliminary method to compare design features. Some aspects of the usability experimentation and the RLEval method appear to be complementary.

The influence of socio-cultural background and product value in usability testing.

This article examines the influence of socio-cultural background and product value on different outcomes of usability tests. A study was conducted in two different socio-cultural regions, Switzerland and East Germany, which differed in a number of aspects (e.g. economic power, price sensitivity and culture). Product value (high vs. low) was varied by manipulating the price of the product. Sixty-four test participants were asked to carry out five typical user tasks in the context of coffee machine usage, measuring performance, perceived usability, and emotion. The results showed that in Switzerland, high-value products were rated higher in usability than low-value products whereas in East Germany, high-value products were evaluated lower in usability. A similar interaction effect of socio-cultural background and product value was observed for user emotion. Implications are that the outcomes of usability tests do not allow for a simple transfer across cultures and that the mediating influence of perceived product value needs to be taken into consideration.

Assessment of microbiological quality of drinking water from household tanks in Bermuda.

Bermuda residents collect rainwater from rooftops to fulfil their freshwater needs. The objective of this study was to assess the microbiological quality of drinking water in household tanks throughout Bermuda. The tanks surveyed were selected randomly from the electoral register. Governmental officers visited the selected household (n = 102) to collect water samples and administer a short questionnaire about the tank characteristics, the residents' habits in terms of water use, and general information on the water collecting system and its maintenance. At the same time, water samples were collected for analysis and total coliforms and Escherichia coli were determined by 2 methods (membrane filtration and culture on chromogenic media, Colilert kit). Results from the 2 methods were highly correlated and showed that approximately 90% of the samples analysed were contaminated with total coliforms in concentrations exceeding 10 CFU/100 mL, and approximately 66% of samples showed contamination with E. coli. Tank cleaning in the year prior to sampling seems to protect against water contamination. If rainwater collection from roofs is the most efficient mean for providing freshwater to Bermudians, it must not be considered a source of high quality drinking water because of the high levels of microbial contamination.

Hot surface temperatures of domestic appliances.

BACKGROUND: Domestic appliances are burning people. In the European Union, accidents requiring hospital treatment due to burns from hot objects account for between 0 and 1% of all such accidents. Young children are particularly at risk. These reported accidents requiring hospital treatment are also likely to be a small proportion of the total number of burns from hot objects. RESEARCH METHOD: There is a lack of hard evidence about the level of accidents, typical consumer expectation and use, and on the state of the art of appliances. Results of technical laboratory tests carried out on products are used to demonstrate the state of the art and also show how consumer expectations could be changing. Results of a survey into accidents, based on a written questionnaire following telephone contact, provide information on non-hospital cases. RESULTS: Results of tests on products show that there are significant differences in the temperatures of touchable surfaces, even in products of the same type. Typically, these differences are due to variations in design and/or materials of construction. Some products are hot enough to burn skin. Accident research indicates that non-hospital medical practices are treating burn injuries, which are therefore not being included into the current accident statistics. CONCLUSIONS: For products with the same function, some types of design or materials of construction are safer, with lower surface temperatures. Many product standards have no or unnecessarily high limits on surface temperatures. Many standards do not address the realities of who is using their products, for what purpose or where they are located. Some standards use unreasonable general limitations and exclusions that allow products with higher surface temperatures than they should have. Many standards rely on the experience factor for avoiding injury that is no longer valid, with the increased availability of safer products of the same type. A major field of work ahead is to carry out more surveys and in-depth studies of non-fatal accidents and injuries.

Assessment of vacuum cleaners and vacuum cleaner bags recommended for allergic subjects.

BACKGROUND: High-quality vacuum cleaners and vacuum cleaner bags are often recommended to allergic patients as a means of reducing indoor allergen exposure. A number of vacuum cleaners on the market today claim to capture 99.9% of particles 0.3 microm or larger entering the vacuum cleaner, and many vacuum cleaner bags are now being sold as microfiltration bags. OBJECTIVE: The purpose of this study was to compare the allergen-trapping abilities of vacuum cleaners and to use a new technique for testing vacuum cleaner bags that are recommended for allergic patients. METHODS: Vacuum cleaners were tested in an 18-m(3) laboratory room permeated with dust containing high levels of cat allergen by using techniques previously described. Air was sampled with parallel filters in conjunction with a particle counter. The filters were assayed by ELISA for cat allergen (Fel d 1). Vacuum cleaner bags were tested by using a modified dust trap to pull sieved house dust containing a known amount of Fel d 1 across the material used for the bag. Allergen passing through the bag was trapped on a filter covering the exit of the trap and analyzed for Fel d 1. RESULTS: In general, vacuum cleaners designed for allergic patients leaked lower amounts of allergen (<0.5-4.04 ng/m(3)) than that found in our previous studies (<0.5-100 ng/m(3)). Single-layer vacuum cleaner bags performed poorly (1250-2640 ng recovered) compared with most of the 2- and 3-layer microfiltration bags (0.53-2450 ng recovered). The range of allergen recovered from the 2-layer bags (0.93-2450 ng recovered) highlighted the variability found between manufacturers. CONCLUSION: The results suggest that although allergen leakage has been reduced, there is still room for improvement. A method of testing allergen leakage by using Fel d 1 should be applied to vacuum cleaners and bags recommended for allergic patients.