Patent ID: 8585799

Claim:
A method comprising: receiving an air flow at an inlet port of an air pre-treatment device; passing the air flow through a first filter for a first duration of time, wherein the first filter comprises a first set of pores each having a first size, and wherein the first filter is configured to prevent passage of first particles in the air flow that are larger than the first size; passing the air flow from the first filter through a second filter for the first duration of time, wherein the second filter comprises a second set of pores each having a second size that is smaller than the first size, and wherein the second filter is configured to prevent passage of second particles in the air flow that have passed through the first filter and that are larger than the second size; expelling the air flow from an outlet port of the air pre-treatment device; and passing the second particles to a first particle detector through a discharge port located between the first and second filter by drawing air through the discharge port after the first duration of time has lapsed.