**7. Effects of pollution on insect abundance**

Industrial pollution has long been known to reduce insect potential [31, 63]. Carbon monoxide from cars and engine exhaust also has its effect, primarily due to high levels of NOx [53, 64]. Though the most critical forms of industrial pollution are heavy metals in soils and waterways [54, 65], air pollution [55, 66], aquatic pollution [56, 67], and light pollution [57, 68]. Although it is somewhat reduced now in many developed nations [58, 69], it is yet a global threat to insect protection. This has drastically affected the population of the insect community, as most insects are sensitive to smell while most have disappeared due to their habitat loss.
