Health Effects

CARBON MONOXIDE

Sources of emissions to atmosphere

The local authorities have worked together in the following areas to inform the public and develop co-ordinated polices

The main outdoor source of carbon monoxide in the UK is currently road transport, which accounts for about 69% of UK emissions (mainly from petrol-engine vehicles). Emissions of Carbon monoxide in the UK declined by 56% between 1990 and 2002 mainly as a result of the introduction of catalytic converters on petrol cars. Fuel switching from non-catalyst petrol cars to diesel cars has also had an effect.

Health Effects

The main threat to human health from exposure to carbon monoxide is the formation of carboxyhaemoglobin in the blood which substantially reduces the capacity of the blood to carry oxygen and blocks essential biochemical reactions in cells.

The formation of carboxyhaemoglobin in the blood of people exposed to carbon monoxide and the amount present depends on the level and duration of exposure, as well as the rate and depth of breathing. Thus someone exercising and breathing more rapidly and deeply will have higher levels than someone resting but exposed to the same concentration.

People who have an existing disease affecting delivery of oxygen to the heart and brain are likely to be at particular risk if these delivery systems are further impaired by carbon monoxide. Cigarette smoke is an important source of carbon monoxide; smokers have much higher levels in their blood than non-smokers.

Carbon Monoxide Air Quality Objective

BENZENE

Sources of emissions to atmosphere

All benzene in the UK at ground level is likely to have resulted from human activities with motor vehicles being the most important single source (benzene is present in petrol where it is used as an anti-knock agent). Since 1 January 2000 EU legislation has required the amount of benzene in petrol to be below 1% (it is presently about 0.7% by volume for fuel sold in the UK).

Health Effects

The effect of most concern from long term exposure to benzene is leukaemia and in particular several types of this disease, known collectively as the non-lymphocyte leukaemia. It acts on the genetic material of cells causing malignant effects. At concentrations occurring in the ambient atmosphere, benzene does not have short-term or acute effects.

Benzene Air Quality Objective

1, 3 BUTADIENE

Sources of emissions to atmosphere

The main source of emissions of 1, 3 Butadiene in the UK is from road transport emissions from petrol vehicles. The only other major source of 1, 3 Butadiene in the UK comes from the chemical industry through the manufacture and use of this chemical.

Health Effects

1, 3 Butadiene is a carcinogen (cancer causing) for which there is no absolutely safe level for human exposure.

1, 3 Butadiene Air Quality Objective

LEAD

Sources of emissions to atmosphere

Emissions of lead in the UK fell significantly between 1990 and 1997 due to the reduction of the lead content of leaded petrol. The sale of leaded petrol was banned from 01 January 2000, which has reduced emissions from transport to almost zero. Emissions of lead are now restricted to a variety of industrial activities, such as battery manufacture, pigments in paints and glazes, alloys, radiation shielding, tank lining and piping.

Health Effects

Direct human exposure to lead occurs through food, water, dust, soil and air. Most people receive the largest portion of their daily intake via food. Effects of lead on human health are quantified by using the concentration of lead in blood as an indicator of exposure. Lead is a cumulative poison and in sufficient amounts can cause sever damage - particularly to the central nervous system. Low level lead exposure may impair children's intelligence and concentration although evidence is not conclusive. The first signs of lead poisoning are headaches, tiredness, constipation and weight loss.

Lead Air Quality Objective

NITROGEN DIOXIDE

Sources of emissions to atmosphere

Nitric oxide (NO) and nitrogen dioxide (NO₂) are often referred to as Nitrogen oxides (NO_x). The principal source of nitrogen oxides emission in the UK is road transport. Major roads carrying large volumes of high-speed traffic are a predominant source, as are conurbations and city centres with congested traffic. Other significant Sources of emissions to atmosphere of nitrogen oxides include the electricity supply industry and other industrial and commercial sectors.

Health Effects

Nitrogen dioxide is an irritant gas, which has been known for many years to have serious and sometimes fatal effects on health when inhaled in the very high concentrations associated with accidental exposures. In combination with other pollutants, the levels of N0₂ found close to busy roads may adversely affect some people with asthma. Nitrogen dioxide may have subtle effects on health at the much lower concentrations that may occur in the ambient atmosphere.

Nitrogen Dioxide Air Quality Objective

SULPHUR DIOXIDE

Sources of emissions to atmosphere

The main source of sulphur dioxide in the UK is power stations, with other significant Sources of emissions to atmosphere from the industrial sector including refineries. Domestic and road transport Sources of emissions to atmosphere are not significant contributors to sulphur dioxide emissions.

Health Effects

Sulphur Dioxide is an irritant when it is inhaled because of its acidic nature. It causes its irritant effects by stimulating nerves in the lining of the nose and throat and in the airways of the lungs. This causes a reflex cough, irritation, and a feeling of chest tightness, and may lead to narrowing of the airways. This is often the case in asthmatics and people suffering from chronic lung disease whose airways are often inflamed and easily irritated.

Sulphur Dioxide Air Quality Objective

PARTICLES (PM₁₀)

Sources of emissions to atmosphere

There is a wide range of emission Sources of emissions to atmosphere that contribute to PM10 concentrations in the UK. Particles arise from a variety of Sources of emissions to atmosphere both natural and man made, and can be divided into three main categories:

Particulate Matter less than 10µm in diameter are divined as PM₁₀. These particles are defined solely by their physical characteristics and no particular chemical composition is implied.

Health Effects

The Committee on the Medical Effects of Air Pollution (an Advisory Committee of independent experts that provides advice to Government Departments and Agencies on all matters concerning the potential toxicity and effects upon health of air pollutants) suggest that healthy individuals are unlikely to experience acute effects from exposure to concentrations of particles found in ambient air in the UK. However there may be an association between levels of particles such as those encountered in the UK and acute affects on people with respiratory and cardiac disease, ranging from exacerbated symptoms of existing illness to earlier death. For this reason, PM10's are now thought to be the most important of the commonly occurring air pollutants.

PM₁₀ Air Quality Objective

The 2010 objectives are provisional and may be incorporated into regulations after the review of the EU first Air Quality Daughter Objective, which is due for completion in 2004.

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