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Air – details

PM2.5 refers to atmospheric particulate matter (PM) that have a diameter of less than 2.5 micrometers, which is about 3% the diameter of a human hair.

Some examples include dust, ash and sea-spray. Particulate matter (including soot) is emitted during the combustion of solid and liquid fuels, such as for power generation, domestic heating and in vehicle engines.

PM2.5 (particles less than 2.5 micrometers in diameter) can penetrate deeply into the lung, irritate and corrode the alveolar wall, and consequently impair lung function. Hence it is important to investigate the impact of PM2.5 on the respiratory system 

PM10 is particulate matter 10 micrometers or less in diameter, PM2.5 is particulate matter 2.5 micrometers or less in diameter. … By way of comparison, a human hair is about 100 micrometres, so roughly 40 fine particles could be placed on its width.

The size of particles affects their potential to cause health problemsPM2.5 (particles with a diameter of 2.5 micrometres or less): these particles are small enough to pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects.

Nitrogen dioxide is part of a group of gaseous air pollutants produced as a result of road traffic and other fossil fuel combustion processes. Its presence in air contributes to the formation and modification of other air pollutants, such as ozone and particulate matter, and to acid rain.

Nitrogen dioxide is an important air pollutant because it contributes to the formation of photochemical smog, which can have significant impacts on human health.

Breathing air with a high concentration of NO2 can irritate airways in the human respiratory system. … NO2 along with other NOx reacts with other chemicals in the air to form both particulate matter and ozone. Both of these are also harmful when inhaled due to effects on the respiratory system

Volatile organic compounds(VOCs) are organic chemicals that have a high vapor pressure at ordinary room temperature. Common examples of VOCs that may be present in our daily lives are: benzene, ethylene glycol, formaldehyde, methylene chloride, tetrachloroethylene, toluene, xylene, and 1,3-butadiene.

Acetone. Found in: nail polish remover, furniture polish and wallpaper. …

  • Benzene. Found in: paint, glue, carpeting and emissions from gasoline combustion. …
  • Butanal. Found in: emissions from barbecues, burning candles, stoves and cigarettes. …
  • Carbon Disulfide. …
  • Dichlorobenzene. …
  • Ethanol. …
  • Formaldehyde. …

Formaldehyde, one of the most common VOCs, is a colourless gas with an acrid (sharp and bitter) smell. It is common in many building materials such as plywood, particleboard and glues. Formaldehyde can also be found in some drapes and fabrics and in certain types of foam insulation.

Other sources of VOCs include the burning of fuels such as gas, wood and kerosene and tobacco products. VOCs can also come from personal care products such as perfume and hair spray, cleaning agents, dry cleaning fluid, paints, lacquers, varnishes, hobby supplies and from copying and printing machines.

VOCs can be released from products during use and even in storage. However, the amount of VOCs emitted from products tends to decrease as the product ages.

What are some health concerns caused by VOCs?

VOCs include a variety of chemicals that can cause eye, nose and throat irritation, shortness of breath, headaches, fatigue, nausea, dizziness and skin problems. Higher concentrations may cause irritation of the lungs, as well as damage to the liver, kidney, or central nervous system. Long-term exposure may also cause damage to the liver, kidneys or central nervous system.

Some VOCs are suspected of causing cancer and some have been shown to cause cancer in humans. The health effects caused by VOCs depend on the concentration and length of exposure to the chemicals.

Most people are not affected by short-term exposure to the low levels of VOCs found in homes. Some people may be more sensitive, such as people with asthma. For long-term exposure to low levels of VOCs, research is ongoing to better understand any health effects from these exposures.

How can I avoid exposure to VOCs?

You can best avoid exposure to VOCs by controlling their source. Use materials and products that do not give off VOCs. Examples are listed below.

  • Some building products give off fewer VOCs than others. Select paints and varnishes that are labelled as containing low VOCs
  • Do not allow smoking in or near your home. Second-hand smoke contains many pollutants, including VOCs
  • Minimize use of scented products such as plug-in or aerosol deodorizers, candles and incense
  • Consider storing furnishings and building materials for at least a few weeks. This will allow gases to be given off before you bring them into your home. If this is not possible, increase the ventilation by opening windows and doors in your home for a few weeks
  • Buy only enough paints, cleaners and solvents for immediate use so you don’t have to store them in your home. Follow instructions on the product label. Keep lids on tightly. Store products in a separate room like an outdoor shed or in areas with proper ventilation
  • Remove old or unnecessary tins or bottles that contain products with VOCs from the home. Do not throw unused products away with your household garbage. Ensure you safely and properly dispose of them. Contact your local municipality or RCBC (Recycling Council of British Columbia) at for more information
  • Avoid bringing recently dry-cleaned clothing into your home if it still has a strong smell. Leave the clothing at the shop, or take it out of the plastic wrapping and hang it in a ventilated area until it is dry

New carpets:

  • If glues are necessary, select those suitable for indoor use
  • Leave the area during carpet installation
  • Ventilate the area as much as possible during the installation using fans and opening windows and doors. Continue to ventilate for several days after installation


  • Make sure you get enough fresh, clean air into your home by opening windows
  • Increase ventilation by opening windows and doors after you bring new VOC sources into your house, such as new carpets, furniture, or drapes
  • Follow manufacturers’ labels when using household chemicals. If the label says “use in a well-ventilated area” go outside or to an area where an exhaust fan or open window provides extra ventilation

Defra AQI air quality index 1-10

Defra publishes a regular score of air pollution in the area – scored 1-10 – but it does not directly relate to the levels of air pollutants described above.

Levels and safety

Currently, the WHO [World Health Orgn.] identifies safe levels of PM10 – particulate matter measuring under ten micrometres – as under 20 micrograms per cubic metre. This is much lower than the EU’s safe particulate matter level, which stands at 40 micrograms per cubic metre.

A large component of PM2.5 in London comes from regional sources, although the biggest contributor is thought to be road transport, predominantly through tyre and brake wear.

During the conference the London Mayor also signed London up to the UN Environment and WHO ‘Breathe Life’ campaign, the first ‘mega-city’, committing to meeting the 10 μg/m3 WHO PM2.5 limit by 2030

In the short term, the US considers it safe if PM2.5 levels don’t go over 35 μg/m3 within a day, so long as the yearly average comes out to 12 μg/m3 per day (in other words, a few days of higher PM2.5 here and there is acceptable, so long as there are only a few).

PM2.5 health categories – (Victoria Aus)

Health category 24-hour PM2.5 μg/m3
Low 0–8.9
Moderate 9.0–25.9
Unhealthy – sensitive 26.0–39.9
Unhealthy – all 40.0–106.9

PM10 – (Victoria Aus)

Air quality category 24-hr PM10 µg/m3 One-hour PM10 µg/m3
Very good 0–16.4 0–26.3
Good 16.5–32.9 26.4–52.7
Fair 33–49.9 52.8–79.9
Poor 50–74.9 80–119.9
Very poor 75 or greater 120 or greater

Low VOC concentration levels is considered to be less than 0.3 mg/m3.

NO2 WHO – In the INDEX report (5), nitrogen dioxide concentrations were in the range of 13–62 μg/m3 indoors, 27–36 μg/m3 at the workplace, 24–61 μg/m3 outdoors and 25–43 μg/m3 for personal exposure.

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