Thank you for collecting data as part of the Citidair project. In this report you will find a summary of your data - statistics, maps, graphs and photos. Please take some time and look over them before answering the questions in the survey (insert link).

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What is air pollution?

Air pollution consists of a variety of gases and tiny particles, not visible to the human eye. These gases and particles almost everywhere, whether you are indoors or outdoors, at home or walking down the road. The concentration, or amount of these pollutants in the air, varies depending on the sources that generate them and where you spend your time. Not everyone is affected in the same way by air pollution. Some people may be more susceptible to than others because of their physiology, genes, age, and/or existing medical conditions. Moreover, how long someone was exposed to a certain amount of an air pollutant also plays a role in a person’s health risk from air pollution exposure.

How is an air pollution measurement represented?

The concentration of an air pollutant is represented as the mass of the pollutant for every cubic meter of air (e.g. micrograms per cubic metre, µg/m3). For gases, you may sometimes see the units of measurement as ppb (parts per billion; i.e. one litre of nitrogen dioxide molecules per billion litres of air).

What air pollutants did we measure and what is the significance of these?

Particulate matter (PM) comprises tiny particles in the air that may be formed from natural sources (e.g. soil, pollen, sea spray) and man-made sources (e.g. motorised traffic, open fires, cookers, air fresheners). Smaller sizes of PM (less than 2.5 micrometres, or PM2.5) may travel deep into your lungs after being inhaled.

There are currently no guidelines for PM2.5 levels in the home, however for outdoor air, the WHO suggests a guideline of 25µg/m3 averaged over 24 hours. Researchers from Berkley University have calculated the deaths attributable to smoking and PM2.5 exposure and then linked them so that we can say that one cigarette per day is the rough equivalent of a PM2.5 level of 22 μg/m3.

NO2 (also known as nitrogen dioxide) is a gaseous air pollutant found in the atmosphere. Its main sources are combustion processes where fossil fuels are burned such as heating, power generation and vehicle engines. Indoor sources include gas appliances, fireplaces and wood burning stoves for example.

It is a toxic gas at very high concentrations exceeding 200 µg/m3 (approx. 100 ppb), and can cause significant airway inflammation. At lower levels, nitrogen dioxide can also irritate the lungs and lower resistance to respiratory infections. The current WHO guidelines for outdoor NO2 concentrations is 40 μg/m3 (approx. 20 ppb) averaged over one year, and 200 μg/m3 (approx 100 ppb) averaged over 1-hour.

Volatile organic compounds (VOCs) are mainly human-made chemicals released as gases from a variety of indoor and outdoor sources through combustion and evaporation. Examples of VOCs are benzene, formaldehyde, toluene or xylene to name a few. All these are commonly found in household products, cosmetics, paints and varnishes, cigarette smoke, pesticides and fuel for example. Generally, concentrations of VOCs are higher in indoor environments than outdoors.

In the UK there are currently no indoor air quality guidelines for individual or total VOCs. The WHO indoor air quality guidelines cover a limited number of individual VOCs only. Common symptoms of acute or short term VOC exposure include headaches, dizziness, eye and respiratory tract irritation. The symptoms vary greatly and depend on the nature of the individual VOC as some are knowingly toxic, while others have no known health effects, as well as the susceptibility of the exposed person.

Statistics

Maps

In these maps you can see the spatial pattern of your air pollution for the period of time when you were collecting data using the Flow 2 and the MicroPEM.

How to explore the maps

Use the + and - icons to zoom in and out of the map. The base layers icon is below the zoom icons and will change the underlying map. The default is black and white to highlight the air pollution measurements, but you might want to change to OpenStreetMap, has more details on the local environment. The colour scale for each pollutant goes from dark purple (low reading) to bright yellow (high reading). If you want to know the exact reading at a particular place then hover over the coloured circles with your cursor. Hovering will also create a red circle in the other maps, which will show you what the reading was like for the other pollutants. The black dots show when you took a photo. If you hover over the black dots a File ID will appear. Link the File ID to the image at the bottom of this report to understand more about your activities during this time.

Quick start to exploring your data

  • Compare the pattern of PM 2.5 measurements in the top left (Flow 2) map compared to the top right (MicroPEM). At which specific locations do you see purple circles in both maps?

  • Compare the pattern between the top left map (Flow 2 PM 2.5) and the bottom left (Flow 2 NO2) and bottom right (Flow 2 VOC)?

Graphs

In these graphs you can see the temporal pattern of your air pollution for the period of time when you were collecting data using the Flow 2 and the MicroPEM.Note that whilst the graph on the bottom left (NO2) and bottom right (VOC) share the same measurement unit (ppb) they are on different scales.

How to explore the graphs

If you hover over the coloured lines with your cursor you can see what the air pollution reading was like at the specific time. If you would like to zoom into a specific area of the graph then left click to start a window and drag to the parts of the graph you would like to focus on (double click to zoom back out). The black dots show when you took a photo. If you hover over the black dots an File ID will appear. Link the File ID to the image at the bottom of this report to understand more about your activities during this time.

Quick start to exploring your data

  • Compare the pattern of PM 2.5 measurements in the light blue (Flow 2) line compared to the dark blue (MicroPEM) line. When are the lines closer and when are they further apart?

  • Compare the pattern of PM 2.5 measurement (blue lines) to the green (NO2) and orange (VOC) line. Do they have the same times when they are high?

  • Look at the black dots on the graphs and match the ID to the photos below. Are there any things in the photos that might explain the air pollution measurements?

Photos

Measures to reduce air pollution exposure

Measures to reduce your exposure to PM include:

Measures to reduce your exposure to NO2 include:

Measures to reduce your exposure to VOCs in your home include: