Question

Multiple Choice Questions
Which particulate size is most harmful?

• A. $1.0\mu$m or less
• B. $1.5\mu$m or less
• C. $2.5\mu$m or less
• D. $5.2\mu$m- $2.5\mu$m.

Answer 1

The correct option is C $2.5\mu$m or less

PM or particulate matter of diameter $2.5\mu$m or less is the most harmful as they are inhaled deep into the lungs causing serious lung damages, deposition in respiratory tracts and even death of the person.

So, the correct answer is $2.5\mu$m or less.