Certain environmental conditions increase the occurrence of diseases. A polluted environment in terms of air pollution poses risk of developing respiratory disease such as asthma in allergic individuals or in the individuals with hyperactive immune system. Likewise, individuals with defective melanin production gene are more likely to develop skin cancer upon exposure to UV lights. Hence, specific conditions stimulate disease occurrence.
So sound travels 1 kilometer in roughly 3 seconds and 1 mile in roughly 5 seconds. When you see the flash of a lightning bolt, you can start counting seconds and then divide to see how far away the lightning struck.
