Objective: To determine if it is possible to deliver a one-quarter reduction in the sodium content of bread without detection. Design: Single-blind, randomized, controlled trial. Setting: The Royal North Shore Hospital in Sydney, Australia. Participants: One-hundred and ten volunteers from the hospital staff that completed 94% of scheduled assessments. Intervention: Six consecutive weeks of bread with usual sodium content or six consecutive weeks of bread with cumulating 5% reductions in sodium content each week. Main outcome measure: The proportion of participants reporting a difference in the salt content of the study bread from week to week. Results: The intervention group were no more likely than the control group to report a difference in the salt content of the bread from week to week (P ¼ 0.8). Similarly, there were no differences between randomized groups in the scores for flavour (P ¼ 0.08) or liking of the bread (P ¼ 0.95) over the study follow-up period. However, the saltiness scores recorded on a visual analogue scale did decline in the intervention group compared with the control group (P ¼ 0.01) Conclusions: A one-quarter reduction in the sodium content of white bread can be delivered over a short time period, while maintaining consumer acceptance. Over the long term, and particularly if achieved for multiple foods, a decrease in sodium content of this magnitude would be expected to reduce population levels of blood pressure and the risks of stroke and heart attack.

Background-A study was undertaken to assess the importance of thunderstorms as a cause of epidemics of asthma exacerbations and to investigate the underlying mechanism. Methods-A case control study was performed in six towns in south eastern Australia. Epidemic case days (n = 48) and a random sample of control days (n = 191) were identified by reference to the diVerence between the observed and expected number of emergency department attendances for asthma. The occurrence of thunderstorms, their associated outflows and cold fronts were ascertained, blind to case status, for each of these days. In addition, the relation of hourly pollen counts to automatic weather station data was examined in detail for the period around one severe epidemic of asthma exacerbations. The main outcome measure was the number of epidemics of asthma exacerbations. Results-Thunderstorm outflows were detected on 33% of epidemic days and only 3% of control days (odds ratio 15.0, 95% confidence interval 6.0 to 37.6). The association was strongest in late spring and summer. Detailed examination of one severe epidemic showed that its onset coincided with the arrival of the thunderstorm outflow and a 4-12 fold increase in the ambient concentration of grass pollen grains. Conclusions-These findings are consistent with the hypothesis that some epidemics of exacerbations of asthma are caused by high concentrations of allergenic particles produced by an outflow of colder air, associated with the downdraught from a thunderstorm, sweeping up pollen grains and particles and then concentrating them in a shallow band of air at ground level. This is a common cause of exacerbations of asthma during the pollen season. (Thorax 2001;56:468-471)