Long term exposure to low level air pollution and mortality in eight European cohorts within the ELAPSE project: pooled analysis

Abstract

Objective To investigate the associations between air pollution and mortality, focusing on associations below current European Union, United States, and World Health Organization standards and guidelines. Design Pooled analysis of eight cohorts. Setting Multicentre project Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) in six European countries. Participants 325 367 adults from the general population recruited mostly in the 1990s or 2000s with detailed lifestyle data. Stratified Cox proportional hazard models were used to analyse the associations between air pollution and mortality. Western Europe-wide land use regression models were used to characterise residential air pollution concentrations of ambient fine particulate matter (PM 2.5 ), nitrogen dioxide, ozone, and black carbon. Main outcome measures Deaths due to natural causes and cause specific mortality. Results Of 325 367 adults followed-up for an average of 19.5 years, 47 131 deaths were observed. Higher exposure to PM 2.5 , nitrogen dioxide, and black carbon was associated with significantly increased risk of almost all outcomes. An increase of 5 µg/m 3 in PM 2.5 was associated with 13% (95% confidence interval 10.6% to 15.5%) increase in natural deaths; the corresponding figure for a 10 µg/m 3 increase in nitrogen dioxide was 8.6% (7% to 10.2%). Associations with PM 2.5 , nitrogen dioxide, and black carbon remained significant at low concentrations. For participants with exposures below the US standard of 12 µg/m 3 an increase of 5 µg/m 3 in PM 2.5 was associated with 29.6% (14% to 47.4%) increase in natural deaths. Conclusions Our study contributes to the evidence that outdoor air pollution is associated with mortality even at low pollution levels below the current European and North American standards and WHO guideline values. These findings are therefore an important contribution to the debate about revision of air quality limits, guidelines, and standards, and future assessments by the Global Burden of Disease.

Cut particulate air pollution, save lives

“…When combined with previous findings,3451011 the findings from this study confirm the direction of effect—increased long term exposure to PM 2.5 increases the risk of mortality, reduced long term exposure to PM 2.5 decreases the risk. The magnitude of the underlying causal effect remains uncertain, however, partly owing to the study’s design.…”

“…More research is needed to quantify the magnitude of the reported effects. Nonetheless, the study by Chen and colleagues adds to the now overwhelming body of evidence that long term exposure to PM 2.5 is associated with mortality,3451011 even in countries such as Canada where PM 2.5 levels are considered low by global comparisons. In response to this evidence, the World Health Organization recently introduced new air quality guidelines, which halved the recommended annual PM 2.5 limit (now 5 μg/m 3 ) 13.…”

“…If translated into policy and legislation, this change will put downward pressure on emissions and save lives. We must, however, remember that evidence of any threshold below which exposure to PM 2.5 is safe for health is lacking 1013…”

Changes in exposure to ambient fine particulate matter after relocating and long term survival in Canada: quasi-experimental study

“…For example, in a large cohort study comprising eight European cohorts, a positive association was observed between PM 2.5 level and deaths from natural causes. 46 In a US national cohort of about 1.6 million respondents to the national health interview surveys, higher PM 2.5 levels were associated with all cause mortality and mortality from cardiopulmonary causes and lung cancer. 47 Similar associations were reported in a Canadian study using the 2001 CanCHEC.…”

“…This study also linked increased PM 2.5 concentrations arising from residential mobility to increased mortality, which is in line with mounting evidence showing the impact of PM 2.5 on increasing mortality in diverse locations, including Europe and north America. For example, in a large cohort study comprising eight European cohorts, a positive association was observed between PM 2.5 level and deaths from natural causes 46. In a US national cohort of about 1.6 million respondents to the national health interview surveys, higher PM 2.5 levels were associated with all cause mortality and mortality from cardiopulmonary causes and lung cancer 47.…”