Spraying of pesticide in AC ducts - a possible cause of an incident

The Hindu Newspaper has reported that employees in a manufacturing unit had to be hospitalised due to the possible spraying of pesticides into an AC duct.The root cause is still being investigated. This raises a larger question of product stewardship. Pesticide Manufacturers in India do post all the warnings in their product but how do we ensure that they are all followed?
Read the article in this link.