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

Abstract

Objective To investigate the association between changes in long term residential exposure to ambient fine particulate matter (PM 2.5 ) and premature mortality in Canada. Design Population based quasi-experimental study. Setting Canada. Participants 663 100 respondents to the 1996, 2001, and 2006 Canadian censuses aged 25-89 years who had consistently lived in areas with either high or low PM 2.5 levels over five years preceding census day and moved during the ensuing five years. Interventions Changes in long term exposure to PM 2.5 arising from residential mobility. Main outcome measures The primary outcome was deaths from natural causes. Secondary outcomes were deaths from any cardiometabolic cause, any respiratory cause, and any cancer cause. All outcomes were obtained from the national vital statistics database. Results Using a propensity score matching technique with numerous personal, socioeconomic, health, and environment related covariates, each participant who moved to a different PM 2.5 area was matched with up to three participants who moved within the same PM 2.5 area. In the matched groups that moved from high to intermediate or low PM 2.5 areas, residential mobility was associated with a decline in annual PM 2.5 exposure from 10.6 μg/m 3 to 7.4 and 5.0 μg/m 3 , respectively. Conversely, in the matched groups that moved from low to intermediate or high PM 2.5 areas, annual PM 2.5 increased from 4.6 μg/m 3 to 6.7 and 9.2 μg/m 3 . Five years after moving, individuals who experienced a reduction in exposure to PM 2.5 from high to intermediate levels showed a 6.8% (95% confidence interval 1.7% to 11.7%) reduction in mortality (2510 deaths in 56 025 v 4925 deaths in 101 960). A greater decline in mortality occurred among those exposed to a larger reduction in PM 2.5 . Increased mortality was found with exposure to PM 2.5 from low to high levels, and to a lesser degree from low to intermediate levels. Furthermore, the decreases in PM 2.5 exposure were most strongly associated with reductions in cardiometabolic deaths, whereas the increases in PM 2.5 exposure were mostly related to respiratory deaths. No strong evidence was found for the changes in PM 2.5 exposure with cancer related deaths. Conclusions In Canada, decreases in PM 2.5 were associated with lower mortality, whereas increases in PM 2.5 were associated with higher mortality. These results were observed at PM 2.5 levels considerably lower than many other countries, providing support for continuously improving air quality.

Trends in Excess Winter Mortality (EWM) From 1900/01 to 2019/20—Evidence for a Complex System of Multiple Long-Term Trends

“…Air pollution (especially in large cities with population growth) -Air pollution is well recognized for its ability to increase systemic inflammation [109], alter aspects of immune function [110], increase incidence of ILI [111], and increase the proportion of persons infected with influenza [112]. It also interferes with influenza vaccination efficiency and is a risk factor for influenza mortality [113].…”

Trends in Excess Winter Mortality (EWM) From 1900/01 to 2019/20—Evidence for a Complex System of Multiple Long-Term Trends

“…Cancer survivors are at far higher risk of influenza mortality [105]. Mortality is reduced by influenza vaccination [106] Air pollution (especially in large cities with population growth) -Air pollution is well recognized for its ability to increase systemic inflammation [107], alter aspects of immune function [108], increase incidence of ILI [109], and increase the proportion of persons infected with influenza [110]. It also interferes with influenza vaccination efficiency and is a risk factor for influenza mortality [111].…”

Memo to COP26 leaders: abandon your hubris, politics, and pride and see the future through young people’s eyes

“…An ingenious study by Canadian researchers supports a direct relation between particulate air pollution, in the form of PM 2.5 concentrations, and death (doi:10.1136/bmj.n2368). 2 Five year mortality in people who moved from highly polluted to less polluted areas fell by up to 13%. The reverse effect was seen in people who moved to more highly polluted areas.…”