diff --git a/ampel-firmware/co2_sensor.cpp b/ampel-firmware/co2_sensor.cpp
index 7110776f7ab9362e431917afa8ebc84cd8bcb653..0420890c1deedc6f0c31b3b36d2b75bf5f39a9c1 100644
--- a/ampel-firmware/co2_sensor.cpp
+++ b/ampel-firmware/co2_sensor.cpp
@@ -133,11 +133,12 @@ namespace sensor {
     }
     /**
      * Display data, even if it's "old" (with breathing).
-     * Those effects include a short delay.
+     * A short delay is required in order to let background tasks run on the ESP8266.
+     * see https://github.com/esp8266/Arduino/issues/3241#issuecomment-301290392
      */
     if (co2 < 2000) {
       led_effects::displayCO2color(co2);
-      led_effects::breathe(co2);
+      delay(100);
     } else {
       // >= 2000: entire ring blinks red
       led_effects::redAlert();
diff --git a/ampel-firmware/config.public.h b/ampel-firmware/config.public.h
index 00339350cf751165bbd1c1ac46f78ef859e46ed5..feb7f4e612f0fecb0b268f58b7b8fbdee04cb6ff 100644
--- a/ampel-firmware/config.public.h
+++ b/ampel-firmware/config.public.h
@@ -59,9 +59,10 @@
  */
 
 // LED brightness, which can vary between min and max brightness ("LED breathing")
-// max_brightness should be between 0 and 255.
-// min_brightness should be between 0 and max_brightness
+// MAX_BRIGHTNESS must be defined, and should be between 0 and 255.
 #  define MAX_BRIGHTNESS 255
+// MIN_BRIGHTNESS, if defined, should be between 0 and MAX_BRIGHTNESS - 1
+// If MIN_BRIGHTNESS is not set, or if it is set to MAX_BRIGHTNESS, breathing is disabled.
 #  define MIN_BRIGHTNESS 60
 
 /**
diff --git a/ampel-firmware/led_effects.cpp b/ampel-firmware/led_effects.cpp
index f654e77e581ec88bfce7c3dd8be9b648740e9583..51ba98b96c3e19df4737c0ef77900fa450e6e231 100644
--- a/ampel-firmware/led_effects.cpp
+++ b/ampel-firmware/led_effects.cpp
@@ -4,16 +4,15 @@
  *****************************************************************/
 namespace config {
   const uint8_t max_brightness = MAX_BRIGHTNESS;
+#if defined(MIN_BRIGHTNESS)
   const uint8_t min_brightness = MIN_BRIGHTNESS;
-  const int kitt_tail = 3; // How many dimmer LEDs follow in K.I.T.T. wheel
-}
-
-/*****************************************************************
- * Configuration  (calculated from above values)                 *
- *****************************************************************/
-namespace config //NOTE: Use a class instead? NightMode could then be another state.
-{
+#else
+  const uint8_t min_brightness = MAX_BRIGHTNESS;
+#endif
   const uint8_t brightness_amplitude = config::max_brightness - config::min_brightness;
+  const int kitt_tail = 3; // How many dimmer LEDs follow in K.I.T.T. wheel
+  const uint16_t poor_air_quality_ppm = 1600; // Above this threshold, LED breathing effect is faster.
+  //NOTE: Use a class instead? NightMode could then be another state.
   bool night_mode = false;
 }
 
@@ -131,6 +130,17 @@ namespace led_effects {
     }
   }
 
+  /**
+   * If enabled, slowly varies the brightness between MAX_BRIGHTNESS & MIN_BRIGHTNESS.
+   */
+  void breathe(int16_t co2) {
+    static uint8_t breathing_offset = 0;
+    uint16_t brightness = config::min_brightness + pixels.sine8(breathing_offset) * config::brightness_amplitude / 255;
+    pixels.setBrightness(brightness);
+    pixels.show();
+    breathing_offset += co2 > config::poor_air_quality_ppm ? 6 : 3; // breathing speed. +3 looks like slow human breathing.
+  }
+
   /**
    * Fills the whole ring with green, yellow, orange or black, depending on co2 input and CO2_TICKS.
    */
@@ -144,6 +154,9 @@ namespace led_effects {
       pixels.setPixelColor(ledId, pixels.ColorHSV(LED_HUES[ledId], 255, brightness));
     }
     pixels.show();
+    if (config::brightness_amplitude > 0) {
+      breathe(co2);
+    }
   }
 
   void showRainbowWheel(uint16_t duration_ms, uint16_t hue_increment) {
@@ -179,18 +192,6 @@ namespace led_effects {
     }
   }
 
-  void breathe(int16_t co2) {
-    if (!config::night_mode) {
-      static uint16_t breathing_offset = 0;
-      uint16_t brightness = config::min_brightness
-          + pixels.sine8(breathing_offset) * config::brightness_amplitude / 255;
-      pixels.setBrightness(brightness);
-      pixels.show();
-      breathing_offset += 3; // breathing speed. +3 looks like slow human breathing.
-    }
-    delay(co2 > 1600 ? 50 : 100); // faster breathing for higher CO2 values
-  }
-
   /**
    * Displays a complete blue circle, and starts removing LEDs one by one. Returns the number of remaining LEDs.
    * Can be used for calibration, e.g. when countdown is 0. Does not work in night mode.
diff --git a/ampel-firmware/led_effects.h b/ampel-firmware/led_effects.h
index d34a9bfb7d42eeca5fd8cf0ca55b037dec604482..3deb809940e61c9d042ddc52614f7b0ec16a08ca 100644
--- a/ampel-firmware/led_effects.h
+++ b/ampel-firmware/led_effects.h
@@ -25,7 +25,6 @@ namespace led_effects {
 
   void setupRing();
   void redAlert();
-  void breathe(int16_t co2);
   int countdownToZero();
   void showWaitingLED(uint32_t color);
   void showKITTWheel(uint32_t color, uint16_t duration_s = 2);