Works with sensirion-sps Arduino lib (the versions below 1.2.0). Data will be in Serial monitor:

#include <sps30.h>
#include <Wire.h>

// Uncomment for serial plotter format
// #define PLOTTER_FORMAT

void setup() {
  int16_t ret;
  uint8_t auto_clean_days = 4;

  SerialUSB.begin(115200);   // Use SerialUSB for MKR boards
  while (!SerialUSB) {
    ; // Wait for USB Serial to be ready
  }
  delay(2000);

  // Initialize I2C on default pins (SDA/SCL on MKR ONE 1310)
  Wire.begin();

  // Initialize Sensirion I2C layer (usually calls Wire.begin internally)
  sensirion_i2c_init();

  while (sps30_probe() != 0) {
    SerialUSB.println("SPS sensor probing failed");
    delay(500);
  }

#ifndef PLOTTER_FORMAT
  SerialUSB.println("SPS sensor probing successful");
#endif

  ret = sps30_set_fan_auto_cleaning_interval_days(auto_clean_days);
  if (ret) {
    SerialUSB.print("error setting the auto-clean interval: ");
    SerialUSB.println(ret);
  }

  ret = sps30_start_measurement();
  if (ret < 0) {
    SerialUSB.println("error starting measurement");
  }

#ifndef PLOTTER_FORMAT
  SerialUSB.println("measurements started");
#endif

#ifdef SPS30_LIMITED_I2C_BUFFER_SIZE
  SerialUSB.println("Your Arduino hardware has a limitation that only allows reading the mass concentrations.");
  SerialUSB.println("See https://github.com/Sensirion/arduino-sps#esp8266-partial-legacy-support");
  delay(2000);
#endif

  delay(1000);
}

void loop() {
  struct sps30_measurement m;
  uint16_t data_ready;
  int16_t ret;

  do {
    ret = sps30_read_data_ready(&data_ready);
    if (ret < 0) {
      SerialUSB.print("error reading data-ready flag: ");
      SerialUSB.println(ret);
    } else if (!data_ready) {
      SerialUSB.println("data not ready, no new measurement available");
    } else
      break;
    delay(100);
  } while (1);

  ret = sps30_read_measurement(&m);
  if (ret < 0) {
    SerialUSB.println("error reading measurement");
  } else {

#ifndef PLOTTER_FORMAT
    SerialUSB.print("PM  1.0: ");
    SerialUSB.println(m.mc_1p0);
    SerialUSB.print("PM  2.5: ");
    SerialUSB.println(m.mc_2p5);
    SerialUSB.print("PM  4.0: ");
    SerialUSB.println(m.mc_4p0);
    SerialUSB.print("PM 10.0: ");
    SerialUSB.println(m.mc_10p0);

#ifndef SPS30_LIMITED_I2C_BUFFER_SIZE
    SerialUSB.print("NC  0.5: ");
    SerialUSB.println(m.nc_0p5);
    SerialUSB.print("NC  1.0: ");
    SerialUSB.println(m.nc_1p0);
    SerialUSB.print("NC  2.5: ");
    SerialUSB.println(m.nc_2p5);
    SerialUSB.print("NC  4.0: ");
    SerialUSB.println(m.nc_4p0);
    SerialUSB.print("NC 10.0: ");
    SerialUSB.println(m.nc_10p0);

    SerialUSB.print("Typical particle size: ");
    SerialUSB.println(m.typical_particle_size);
#endif

    SerialUSB.println();

#else
    SerialUSB.print(m.nc_0p5);
    SerialUSB.print(" ");
    SerialUSB.print(m.nc_1p0  - m.nc_0p5);
    SerialUSB.print(" ");
    SerialUSB.print(m.nc_2p5  - m.nc_1p0);
    SerialUSB.print(" ");
    SerialUSB.print(m.nc_4p0  - m.nc_2p5);
    SerialUSB.print(" ");
    SerialUSB.print(m.nc_10p0 - m.nc_4p0);
    SerialUSB.println();
#endif

  }

  delay(1000);
}