Pollution - air
The Environmental Protection Unit operates a number of individual diffusion tube sites throughout the borough. These diffusion tubes measure the amount of nitrogen dioxide in the air we breathe.
The quality of the air we breathe is important for our health and wellbeing. During large scale events such as the fire at the fuel depot site at Buncefield, the pollution of the air is a very obvious and visible occurrence. However, pollution from traffic and industry is quite often not visible but is still present.
Hertfordshire and Bedfordshire local authorities have been monitoring air quality for a number of years and in 1999 formed the Hertfordshire and Bedfordshire Air Pollution Monitoring Network (HBAPMN). Hertsmere Borough Council being a member of the Network. All local authorities have been assessing air quality across their areas and comparing it against national objectives, set out in the Government's Air Quality Strategy, for a number of pollutants including carbon monoxide, benzene, 1,3 butadiene, lead, nitrogen dioxide, particulate matter and sulphur dioxide. Where air quality is poor an Air Quality Management Area is declared and, where possible, local action taken to improve the air in that area.
Currently Hertsmere's Pollution Team monitors for nitrogen dioxide.
In May 1997 the Government produced the National Air Quality Strategy (NAQS). The strategy represents a comprehensive approach to maintaining and improving the quality of ambient air in the United Kingdon.
Outlined in the strategy are the air quality objectives for a number of pollutants the Government feels are of most concern at present. Three of these objectives are detailed below.
PM10 Particulates
PM10 describes the fraction of airborne particulate matter that is less than 10 microns in size. These fine particles are of the greatest concern since they are capable of being easily transported over long distances on currents of air. Also, fine particles may be drawn into the lungs where they may adversely affect health. Recently, the attention of scientists has been drawn toward studying the PM2.5 fraction and even smaller particles, which can penetrate the very deepest parts of the lung.
PM10 and other particulate matter may vary considerably in chemical and physical composition. The principal sources of these particles are combustion processes, including traffic and industry.
Nitrogen Dioxide (NO2)
Nitrogen dioxide is one of a number of nitrogen oxides, which are formed during high temperature combustion processes. Road traffic is the main source, accounting for approximately 50% of all European emissions. Therefore, concentrations tend to be highest in urban environments with high traffic levels. Large industrial sources can also have a significant impact. In Hertsmere, almost all N02 comes from transport based emissions.
Nitrogen dioxide is a respiratory irritant and also plays a part in the production of another atmospheric pollutant, Ozone. Nitrogen oxides remain in the atmosphere for approximately one day before they are oxidised to nitric acid. Nitrogen oxides are therefore a contributory factor in the production of acid rain.
Ozone (O3)
Ozone is a very reactive chemical, which is potentially toxic to both plants and animals. Up in the Stratosphere, ozone helps to protect the earth from the harmful effects of ultra-violet rays from the sun. However at ground level it is a pollutant. Unlike the other pollutants mentioned above, ozone is not emitted directly. Rather, it is formed as a result of a complex series of reactions involving hydrocarbons, sunlight and nitrogen dioxide (NO2). The involvement of sunlight in this process means that ozone levels tend to be highest in summer.
The reactions take time to generate ozone and the highest concentrations are frequently experienced many miles away from the source of the pollution, perhaps in rural areas. In fact, a significant proportion of ozone incidents experienced in the UK are due to pollution imported from abroad. The problem of ozone pollution can therefore only be adequately dealt with as a result of international agreements.
There are no substantial sources of Sulphur Dioxide (S02) pollution within Hertsmere and it is not of concern.
Where can I get more information?
The HBAPMN aims to provide consistency in monitoring across the region and collates air quality monitoring results from across Hertfordshire and Bedfordshire. This data is available to the public on the network website listed below. The website gives air quality data for Hertsmere Borough Council as well as all local authorities in Hertfordshire and Bedfordshire. Another useful site that provides informtion and legislation on air quality is the Government site Department of Environment for Food and Rural Affairs, the Government body that deals with air quality. See below for the Defra website.
All local authorities report to Defra regarding the progress they are achieving for air quality. See below for the most recent reports:
Updating and Screening Assessment 2006 (USA) 
This report in June 2006 concludes that Hertsmere Borough Council is not required to carry out a Detailed Review and Assessment for carbon monoxide, benzene, 1,3 butadiene, lead, nitrogen dioxide, PM10 or suphur dioxide.
This detailed assessment confirmed that the air quality objective for nitrogen dioxide will not be achieved at residential properties close to the Broadway at the junction of Darkes Lane, Mutton Lane and Baker Street. The report recommended that Hertsmere Borough Council declare this area as an Air Quality Management Area.
Air Quality Review and Assessment 2008
The Air Quality Review and Assessment 2008 highlight the need for further investigation in areas Southgate Road, Potters Bar and Park Road, Radlett for nitrogen dioxide.
Updating and Screening Assessment 2009 (USA)
This report proposes actions to undertake further monitoring of nitrogen dioxide at High Street Bushey and Watling Street / Aldenham Road junction Radlett. To carry out detailed assessments for Elstree Crossroads, Southgate Road / Barnet Road / High Street Potters Bar and junctions of Watling Street / Aldenham Road and Watling Street / Park Road Radlett, plus M1 Bushey at Hartspring Lane.
Following on from the USA 2009 the Detailed Assessment recommends that the exisiting AQMA at Potters Bar High Street is amended. The existing AQMA at Elstree Crossroads is extended.
The proposed actions from this report recommend continuing monitoring of nitrogen dioxide at High Street Bushey and Watling Street / Aldenham Road Radlett. To complete the 2010 Detailed Assessment recommendations at Elstree Cross Roads, Barnet Road / Southgate Road / High Street and the High Street at the bus station. Radlett junctions of Watling Street / Aldenham Road and Watling Street / Park Road and Hartspring Lane M1
The new monitoring data has not yet identified an immediate need to proceed to a Detailed Assessment for any pollutant. However the results for Shenley Road may need to undergo a Detailed Assessment after the 2012 USA.
Hertsmere Borough Council Air Quality Action Plan Progress report
An action plan report is produced once an AQMA has been declared. This document is a report on the progress Hertsmere Borough Council has made on the 2003 Action Plan.
If you need further information regarding Air Quality in Hertsmere Borough Council please contact Sarah Hoggett, Senior Environmental Health Officer on 020 8207 2277 or e-mail sarah.hoggett@hertsmere.gov.uk