1) Materials and methods HEL activity was examined under various air pollutants
in the smog chamber. The concentration of HEL was 5 mgjml and then 3 III of this solution
was absorbed in the filtrating paper, which were punched out at 6 mm diameter. 10 sheets
of this paper were exposed with one air pollutant in the smog chamber under 100%
humidity. HEL activity in exposed sheets was measured by lisoplate method. The value
of HEL activity at non-exposure was defined as 100%. 10 experiments for one pollutant
were repeated, and then the average values were picked up.