Which of the following forms of pollution is the least harzardous to man ??

Among the given options, the least hazardous form of pollution to man is "A sound of 50 decibels in the air." Sound pollution is the presence of unwanted sound that can harm human health and the environment. A sound of 50 decibels is considered to be in the range of normal conversation or background noise, which is relatively harmless to humans. On the other hand, toxic waste disposed in rivers can pollute the water and harm aquatic life, and chemicals used for fishing can accumulate in the food chain and harm both animals and humans. Flaring of gas from refineries can release harmful gases into the air, causing air pollution and posing health risks to people living nearby.