Air contaminants

There are two types of particulate matter (small particles) in the air:

• large deposited particles - for example dust
• fine particles (PM₁₀) - for example smoke particles from fires.

Deposited particles

Wind blown dust, volcanic eruptions, fires and pollen are sources of deposited particles. Particles are generally larger than 20 microns across (about half the thickness of a human hair). They can cause health effects such as allergies, and settle on surfaces, making them dirty. There are no national guidelines.

Fine particles (PM₁₀)

The major sources of fine particles are home fires, motor vehicles and power stations. Volcanic eruptions also produce PM₁₀. Fine particles make the air hazy, reducing visibility. Smaller than 10 microns across, they are about a fifth the width of a human hair. PM₁₀ can affect health when breathed in, especially for people with asthma or susceptible to respiratory illnesses. We monitor  local PM₁₀ levels at a number of sites throughout the region.

The national  and regional guideline for PM₁₀  is:

• 50 µg/m³ as a 24 hour average.

The National Environmental Standard PM₁₀is:

• 50 µg/m³ as a 24 hour average(one allowable exceedance per year).

Carbon monoxide (CO) is a poisonous gas that’s colourless, odourless and tasteless. It’s poisonous because it attaches to our red blood cells better than oxygen - reducing the blood’s ability to carry oxygen around the body. Low exposure to carbon monoxide causes headaches, dizziness and nausea. High exposure can lead to death.

Carbon monoxide is generally found at levels that are of concern in urban areas where there are high-density housing and busy roads.

Normally, when there is plenty of oxygen present burning fuel will give off carbon dioxide (CO₂). The carbon (C) comes from the fuel and the oxygen (O₂) comes from the air. But, when there’s not enough oxygen present, only one oxygen molecule binds with a carbon – forming carbon monoxide (CO).

The national and regional guidelines for carbon monoxide are:

• 30 mg/m³ as a one hour average
• 10 mg/m³ as an eight hour average.

The National Environmental Standard for carbon monoxide is:

• 10 mg/m³ as an eight hour running average (one allowable exceedance per year)

Carbon dioxide (CO₂) is a greenhouse gas that’s colourless and odourless. Carbon dioxide is being constantly circulated in the environment. It’s naturally released by:

• animal respiration
• decomposition of plants and animals
• volcanic eruptions.

However, people have caused the amount of CO₂ in the atmosphere to significantly increase by:

• burning carbon containing fuels such as oil, coal, natural gas and wood
• clearing forests and draining peatlands.

Increases in CO₂ in the atmosphere are likely to be responsible for global warming which may cause climate change. There are no national guidelines.

Methane (CH₄) is a powerful greenhouse gas that has 20 times the warming potential of CO₂. Also known as natural gas, methane is lighter than air and is odourless.

In the Waikato region the main source of methane comes from the digestion system of livestock. Other sources include landfills, anaerobic decay and accidental emissions of natural gas (for example when filling gas bottles).

There are no national guidelines. 

Oxides of nitrogen include nitrogen dioxide (NO₂) and nitric oxide (NO).

Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as the flu. Nitrogen dioxide and nitric oxide also react with sunlight and volatile organic compounds to produce smog.

Major sources of NOx are combustion in motor vehicle engines, gas appliances, and thermal power stations.

The national and regional guidelines for nitrogen dioxide are:

• 200 µg/m³ as a one hour average
• 100 µg/m³ as a 24 hour average.

The National Environmental Standard for nitrogen dioxide is:

• 200 µg/m3 as a 1 hour average (nine allowable exceedances per year)

Sulphur oxides are colourless gases that smell strongly at high levels. They are produced from the combustion of fossil fuels such as coal and oil during industrial processes and from geothermal eruptions.
The national and regional guidelines for sulphur dioxide are:

• 350 µg/m³ as a one hour average
• 120 µg/m³ as a 24 hour average

The National Environmental Standard for sulphur dioxide is:

• 350 µg/m³ as a 1 hour average (nine allowable exceedances per year)
• 570 µg/m³ as a 1 hour average (no allowable exceedances per year).

Hydrogen sulphide (H₂S) is a colourless gas that smells like rotten eggs. Apart from the unpleasant odour, H₂S can irritate the eyes and respiratory system. High concentrations can kill people (high concentrations cannot be smelled because they paralyse the nerves we smell with).

Sources of hydrogen sulphide include geothermal areas and decaying sulphur-containing materials (for example in sewage ponds).

The national and regional guidelines for hydrogen sulphide are:

• 7 µg/m³ as a 1 hour average.

Lead (Pb) is a poisonous metal that affects people’s nervous system, blood pressure and immune system. Motor vehicle emissions used to be the main source of lead in the Waikato. In the mid 1980s steps were put in place to reduce and eventually remove lead from fuels. This has eliminated a major source of lead in the environment and lead is no longer of concern to air quality.

Lead-based paint is still a source of lead poisoning. Although it’s not used for exterior house paint in New Zealand anymore, lead-based paint can still be found on some older houses (especially those built before the late 1970s).

If your home has lead-based paint, you can reduce the risk of lead poisoning by:

• Hiring a professional to remove the paint when redecorating.
• Keeping surfaces as clean and dust-free as possible.
• Washing your hands before eating.
• Keeping children away from areas where paint is chipped or peeling.

The national and regional guideline for benzene is:

• 3.6 µg/m³ as an annual average.

Volatile organic compounds (VOCs) include a large range of organic materials that create fumes, for example, benzene. Depending on the type, VOCs can affect human health, reduce visibility, and smell bad. Sources of VOCs include industry, vehicles and some types of vegetation.

There are no national guidelines.

Odours are caused by mixtures of chemicals that stimulate the nerves we smell with. An unpleasant, strong, long-lasting odour can be a severe nuisance, reducing our enjoyment of life.

Sources of odour in the Waikato include pulp and paper manufacturers, rendering plants, waste water treatment plants and intensive indoor animal farms (for example piggeries and poultry farms).

There are no national guidelines.

Agrichemicals are chemicals (other than fertiliser) used in agriculture. They include fungicides, insecticides and herbicides. Agrichemical spray drift can affect human health and nearby crops that are not the target of spraying.

There are no national guidelines.

Although ozone in the upper atmosphere protects the planet from damaging ultraviolet rays, at ground level it is an unwanted pollutant. Ozone can affect our health (by causing respiratory problems), and the environment as it is harmful to vegetation.

The national and regional guidelines for ozone are:

• 150 µg/m³ as a one hour average
• 100 µg/m³ as an 8 hour average

The National Environmental Standard for ozone is:

• 150 µg/m³ as a 1 hour average (no allowable exceedances per year).