B. and diesel exhaust particles. These toxicants are reviewed in terms of their relevant chemical characteristics and hazard potential, ability to induce airway dysfunction, and potential for driving the asthma phenotype. Special emphasis is placed on their interactive nature with other triggers and drivers, with regard to driving the asthma phenotype. Overall, both allergic and non-allergic environmental factors can interact to acutely exacerbate the asthma phenotype; some may also promote its development over prolonged periods of untreated exposure, or possibly indirectly through effects around the genome. Further therapeutic considerations should be given to these environmental factors when determining the best course of personalized medicine for individuals with asthma. where the increased risk was almost five occasions. Although sensitization to and house dust were the two allergens that provided the highest risk of developing asthma, there was also a positive correlation with ryegrass, ragweed, and oak (Gergen & Turkeltaub, 1992). The NHANES III data, which resulted in 2007, revealed that of 10 allergens tested for, only cat, exhibited significant increases in bronchial hypersensitivity (Nelson et al., 1999). In addition to the NHANES and CAMP data, there have been many more studies in the United States that have examined the seasonal effect of allergens on asthma. One such study looked at the median weekly asthma admissions by age group to a hospital in Maryland from 1986-1999. The researchers concluded that BET-BAY 002 asthma admissions increase four- to eightfold BET-BAY 002 in the BET-BAY 002 fall compared to the summer time (Blaisdell et al., 2002). BET-BAY 002 A study from 1986 established that P19 the largest number of asthma admissions to a hospital in California occurred during the grass-pollen season (Reid et al., 1986). Recently a study examined the effect of heat and season on adult emergency department visits for asthma in North Carolina. This study found that the number of ER visits for asthma peaked in February (when daily temperatures were coldest) and were lowest in July (when daily temperatures were warmest) (Buckley & Richardson, 2012). International studies have also revealed the same seasonal phenomenon. For example, one study looked at the hospital admissions for asthma in Malta. Analysis revealed a peak in January and a trough in August for both pediatric and adult hospital admissions for acute asthma exacerbations (Grech, Balzan, Asciak, & Buhagiar, 2002). Another study in the Netherlands concluded that there was a decline in asthma symptoms and asthma medication use during the summer time period and a peak during autumn to spring in pediatric patients over a one year time period (Koster, Raaijmakers, Vijverberg, van der Ent, & Maitland-van der Zee, 2011). Another study revealed that in Taiwanese children aged 6C8, asthma and rhinitis peaked in winter, especially in December. However, they also found that children aged 13C15 had two peaks (winter and summer time) for asthma and rhinitis (Kao, Huang, Ou, & See, 2005). In another study done in Taiwan, school-aged children had a sharp increase in the number of asthma admissions in September and March that synchronized with school re-openings (Xirasagar, Lin, & Liu, 2006). An additional study from Taiwan revealed differences among adult and childhood asthma seasonality. Although the asthma-related hospital admission for adults remained low in summer time and increased in winter, the researchers concluded that adult asthma hospitalizations were highest in spring and significantly correlated with air pollution and climate (Chen, Xirasagar, & Lin, 2006). In Australia, researchers have recently found that there is a clear relationship between increased risk of childhood asthma emergency room visits and increased levels of ambient grass pollen (Erbas et al., 2012). In Canada, a study using a national data set compared asthma.