Li Chih-shan points out that in the past, when the air quality was good, perhaps as many as 100 allergen particles would be needed to induce an allergic reaction. Now, with so many pollutants suspended in the air and with the irritation caused by sulfur oxides and nitrogen oxides, people have much lower resistance, and only 50 such particles may now do the trick.
李芝珊指出，過去在空氣品質良好的情況下，可能要一百個過敏原才會讓人過敏；現在經由空氣中懸浮微粒、硫氧化物、氮氧化物等汙染物的刺激，使人的抵抗力減弱，只要五十個過敏原就會讓人產生過敏反應。