Hope Valley air quality and the impact of burning on the Moor

Hello everyone

It has been a year since we deployed our first Air Quality sensors in the Hope Valley, a big Thank-you if you are hosting a sensor. We now have 12 of them spread throughout the Valley

Link to Report on Moor Burning and AQ

The  sensors have been quietly logging data and this has been collected in the Global Sensor Community database where it is freely available for all to view.

As it is an anniversary we thought it might be a good time to review what we have learned about the Hope Valley’s Air Quality.

For some context, the World Health Organization has published air quality threshold guidelines, these are below. In the guidelines “PM” refers to Particulate Matter and the number following refers to the size in microns of the particle being measured. According to the WHO, when these ranges are exceeded, there are substantial health risks if the conditions extend for any period of time. This is why there is a short term and an annual exposure threshold.

PM 2.5: 10 µg/m3 annual mean,  25 µg/m3 24-hour mean 

PM 10: 20 µg/m3 annual mean,  50 µg/m3 24-hour mean

We measure both of these PM sizes (2.5 & 10) on our Hope Valley AQ network and this is why the images shown on the special report always have two traces, one for each particle size.

Overall yes, our air quality is very good based on the comparable data we see elsewhere on the global sensor community, especially in urban areas in the summer months whereas in the Hope Valley our PM counts are usually well below the WHO thresholds. However there are some exceptions to this steady state which can be noted.

  1. In colder weather we see higher particulate counts in the evening in  the villages as opposed to out of them. This is most likely due to wood and coal burning in homes but it is very localised and does not seem to have a widespread impact beyond a street or two. It’s also not a very high reading, but it is noticeable. Occasionally wind will blow a smoke plume from a chimney directly towards a sensor and then the reading is very high for a short time. Also we have observed that the particle sensors are affected by water droplets in the air so when we have fog conditions they often read very high particulate numbers. Additionally very high humidity (over 85%) can cause higher readings.
  • Another contributor to high particulate counts is the seasonal burning of our surrounding moors. This process, used to clear the moors in order to prepare them for the shooting season, is legal until mid-April each year and appears to create a substantial spike in particulates, often well above the hazard thresholds mentioned earlier. 

You can see a report on a moorland burn which was recorded on March 5 in the report linked here.


I am not an air quality scientist or a data scientist so I can only offer a few general observations. However if you have expertise in any of these areas and would like to share insights, please contact HVCA and we would love to have your insights.

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Hope Valley Climate Action (Reg. No. 1192830) is a CIO – Foundation.   Registered 17 Dec 2020.
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