WHY is the smell of thunderstorms dangerous?

Have you ever detected a particular thunderstorm's smell? That is the odour of ozone, which is an allotropic modification of oxygen. Electrical discharges cause the gas to form.

Ozone (O3) is an active substance that oxidises quickly. Breathing in ozone-contaminated air causes respiratory problems. We can conclude that inhaling the odour of thunder is hazardous.

However, there is another side to the coin. The atmosphere's ozone layer shields Earth from cosmic rays.