Figure 3. Heatmap for the prevalence of positive SIgE tests for allergens in different regions. From left to right, top to bottom, the figures are the results of d1: House dust mite, i6: German cockroach, tx4: Tree pollen mix, e5: Dog dander, f1: Egg whites, f2: Cow’s milk, f23: Crab, f24: Shrimp. (The deeper the red is, the higher the prevalence. The number of the total cases in Northwest China for all 9 allergens and in North China for tx4 were less than 50, so the prevalence in those regions was not calculated. The maps were generated by using R studio 3.6.2)