The key words “air pollution and health” produce over 500 references a year from Medline alone. The present review is therefore, of necessity, our selection of just some of the major studies. The selection is based on a systematic Medline search until early 2002, on more than 20 years of continuous research in the field, and on participation in many advisory boards nationally and internationally.
ReviewAir pollution and health
Section snippets
A new era of air pollution research
20 years ago, the era of successful abatement of traditional air pollutants culminated in a voluminous review of the health effects of ambient particulates.23 At concentrations seen in the late 1970s in the developed world, adverse health effects were then regarded as unlikely. In the two decades since then, however, air pollution has re-emerged as a major environmental health issue. One reason is that, although air pollution from combustion of traditional fossil fuel is now present in much
Pollutants of current interest: ozone, particulates, nitrogen dioxide
Now that the concentration of sulphur dioxide has decreased strikingly, attention has shifted to ozone, nitrogen dioxide, and particulates. Before discussing these pollutants in more detail, some qualification is needed to put our discussion in a wider global perspective. For millions of people living in rural areas in developing countries, indoor pollution from the use of biomass fuels occurs at concentrations that are orders of magnitude higher than currently seen in the developed world.36, 37
Short-term studies
There have been abundant studies on the short-term effects of air pollution on health, with emphasis on mortality and hospital admissions. Panel studies have been done in volunteers, which have provided data on health endpoints such as respiratory and cardiovascular symptoms, and objective measures of lung or cardiac function on a daily or weekly basis. Large, collaborative efforts are under way in Europe and the USA which will be summarised.
In Europe, the APHEA (Air Pollution and Health: a
Mechanisms
Chamber studies provide a method by which to pursue the acute mechanisms of individual air pollutants, but do not reproduce either the mixtures or temporal variation that occur in natural exposures. Although individual air pollutants can exert their own specific individual toxic effects on the respiratory and cardiovascular systems, ozone, oxides of nitrogen, and suspended particulates all share a common property of being potent oxidants, either through direct effects on lipids and proteins or
Air quality guidelines and standards
Several guidelines and standards exist for ozone, nitrogen dioxide, and particulate matter in ambient air. The table lists the most recent air quality guidelines and standards recommended by WHO, the US Environmental Protection Agency, and the European Union (EU). The EU standards are targets to be reached in 2005 or 2010. The most remarkable difference lies in the annual value for nitrogen dioxide. The WHO and EU value is only 40% of the US value.
WHO has not proposed guidelines for particulate
Thresholds
A key question is whether threshold concentrations exist below which air pollution has no effect on population health. If such a threshold could be identified, no additional public-health benefits would be expected from bringing air pollution concentrations far below this level. Theoretical and empirical work has been done to shed light on this issue.108, 109 In an analysis of NMMAPS data, no evidence was found for a threshold for PM10 and daily all-cause and cardiorespiratory mortality.109 By
Disputing the evidence
In view of the potentially large costs and benefits associated with abatement of air pollution, questions surrounding the relation between air pollution and health have been an area of fierce debate in the past decade. The early time-series studies have been criticised for their analytical approach and inadequate control for confounding by weather variables etc, whereas the US cohort studies have been criticised for inadequate confounder and co-pollutant control. Reanalyses of such studies were
Concluding remarks
An excess risk of death of “0·5% per 10 μg/m3 PM10” requires some translation before the effect on public health becomes clear. For the Netherlands (16 million inhabitants, about 140 000 deaths per year, and an average PM10 concentration of >30 μg/m3), the number of deaths attributable to day-to-day variations in PM10 would translate into at least 2100 deaths brought forward by air pollution per year—almost twice the number of deaths due to traffic accidents. Estimates derived from the cohort
Search strategy and selection criteria
References (147)
- et al.
The Meuse Valley fog of 1930: an air pollution disaster
Lancet
(2001) Air pollution and asthma
J Allergy Clin Immunol
(1999)Air pollution in asthma: effect of pollutants on airway inflammation
Ann Allergy Asthma Immunol
(2001)- et al.
Indoor air pollution from biomass combustion and acute respiratory infections in Kenya: an exposure-response study
Lancet
(2001) - et al.
Increased plasma viscosity during an air pollution episode: a link to mortality?
Lancet
(1997) - et al.
Long-term ambient ozone concentration and the incidence of asthma in nonsmoking adults: the AHSMOG Study
Environ Res
(1999) - et al.
Asthma in exercising children exposed to ozone: a cohort study
Lancet
(2002) - et al.
Effect of ozone and nitrogen dioxide on the release of proinflammatory mediators from bronchial epithelial cells of nonatopic nonasthmatic subjects and atopic asthmatic patients in vitro
J Allergy Clin Immunol
(2001) - et al.
Effect of domestic concentrations of nitrogen dioxide on airway responses to inhaled allergen in asthmatic patients
Lancet
(1994) - et al.
Human alveolar macrophage phagocytic function is impaired by aggregates of ultrafine carbon particles
Environ Res
(2001)