Car Particulate Matter Sensors are primarily used to monitor the concentration of suspended particulate matter in the air—both inside and outside the vehicle—in real time, thereby safeguarding the health of occupants and supporting emissions control efforts.

These sensors are capable of precisely detecting harmful particulates such as PM2.5 (≤ 2.5 microns) and PM10 (≤ 10 microns), which originate from sources including exhaust fumes, smog, airborne dust, smoking, or off-gassing from interior materials. Their core function is manifested in the following two key areas:

1. Enhancing In-Cabin Air Quality
By utilizing laser scattering technology to sense particulate concentrations within the cabin in real time, the sensors interface with the vehicle's HVAC system to automatically switch between fresh air intake (external circulation) and air recirculation (internal circulation) modes.

When poor air quality is detected outside the vehicle, the system automatically closes the fresh air intake and activates the HEPA filtration system for purification; conversely, when external air quality is good, it allows fresh air to enter, thereby enabling intelligent ventilation.

High-end vehicle models further integrate negative ion generators or plasma purification technologies to actively precipitate particulate matter, thereby improving the respiratory environment for occupants.

2. Supporting Exhaust Emissions Regulation
Installed at the tailpipe of diesel vehicles, these sensors monitor the emission levels of soot particulates downstream of the Diesel Particulate Filter (DPF).

By analyzing changes in electrical resistance or pressure differentials, the system assesses the degree of particulate accumulation and triggers a "regeneration" cycle (a high-temperature combustion process designed to burn off accumulated carbon deposits), thereby ensuring compliance with emissions standards.

Data is transmitted via the CAN bus to the Engine Control Unit (ECU), where it serves as input for On-Board Diagnostics (OBD) monitoring and as a basis for annual environmental compliance inspections.

Currently, the prevailing technology employed is the optical scattering method, which offers advantages such as rapid response times, low manufacturing costs, and high stability; this technology has already been widely adopted in vehicles compliant with the China VI (National VI) emissions standards.