The results indicate that Model 5 has a good temperature and performance based on the minimum and maximum temperature gradient, Index of uniform temperature (IUT), however has a more pressure drop.
Three measures of daily ambient heat were constructed using meteorological observations from the National Climatic Data Center (maximum temperature, heat index) and the Spatial Synoptic Classification.
The association between hyperthermia-related ED visit with various measures of ambient heat as found in previous epidemiologic studies was examined – maximum temperature, heat index and Spatial Synoptic Classification [ 7, 19- 22], since there is no unanimity on any one measure being superior to others [ 23].
Daily mean temperature data were aggregated from daily minimum and maximum temperatures, an index designed to better estimate exposure as it uses multiple observations per day and so should be less prone to measurement error compared with other temperature indices (21).
The following metrics were assessed: minimum, average, and maximum temperature, maximum heat index, the exponential temperature transformation, SSC (categorical), and deviation from normal maximum temperature (categorical).
The odds ratio of ED visit for maximum temperature and heat index remain unchanged with inclusion of other variables (Table 2).
The average temperature profile (using daily maximum temperature, maximum heat index and SSC) were calculated for the days of ED visit and compared with the 'control' days by the climate regions.
In the referred comprehensive Swedish/Thai field study performed in Thailand, there was a significant influence by climate, maximum temperature and heat index on litter size, farrowing rate and weaning to first service interval [ 28].
A heat wave was defined as a block of two or more consecutive days leading to the ED visit when daily maximum temperature or heat index was above the 95th percentile of the 30-year normal for the station [ 24].
During the experimental period, the minimum and maximum temperature-humidity indices (THI) were 86.4 ± 2.5 and 91.5 ± 2.7 during the day and 74.2 ± 2.1 and 81.0 ± 2.5 during the night, respectively, indicating conditions appropriate for induction of extreme heat stress.
