Dr Alison Rivett from the School of Chemistry and co-workers from Bristol University, looked at whether deaths due to respiratory and cardiovascular disease could be associated with any or all of three things:
- Ozone levels, known to cause inflammation of the respiratory tract and aggravate existing lung disease;
- Very fine particles (particulates) which can penetrate deep into the lungs and are linked with heart and lung disease;
- Complex mix of chemicals in the air (VOCs), mainly produced by traffic fumes, many of which may cause cancer, make breathing difficult, or are toxic.
Rivett showed that cardiovascular deaths in the over-65s were mainly linked to an increase in particulates, with increased ozone levels having a slightly lesser effect, whilst deaths in this age group from respiratory illnesses were associated with increased levels of VOCs.
The government's air quality index showed that pollution levels in the Bristol area during the period concerned were either low or moderate, never high or very high. Dr Rivett said: 'Levels of pollutants in the Bristol area are not generally considered to be dangerous to human health, but these findings, which are in keeping with studies from other cities, suggest that further research into the short and long-term effects of low-level pollution is warranted.'
The average number of deaths per day in the Bristol area is 23. About 45% are from cardiovascular disease and 15% from respiratory illnesses. Despite the small size of the daily statistical sample, over the three year period investigated an association was clearly identified between daily concentrations of pollutants, notably particulates, and mortality.