Weekly journal scan: every breath you take, air pollution impacts your cardiovascular health

Key Points• In this population-based cohort study, the authors estimated exposure-response associations between chronic exposure to fine particulate matter <2.5 μm in diameter (PM 2.5 ), a critical component of air pollution, and the risks of a first hospital admission for seven major cardiovascular disease (CVD) subtypes [ischaemic heart disease (IHD), cerebrovascular disease, heart failure (HF), cardiomyopathy (CMP), arrhythmias (AR), valvular heart disease (VHD), and thoracic and abdominal aortic aneurysms (AA)] or a composite of these CVD.Subgroup analyses were performed based on individual-and neighbourhood-level factors to identify susceptible groups. 1 • The study included nearly 60 million Medicare beneficiaries aged ≥65 years (most aged 65-74 years at study entry; 84% white; 55% female) who resided in the contiguous USA and had enrolled in the fee-for-service programme during 2000-16.Drawing from a variety of air pollution data sources (such as satellite data, meteorology, land use variables, and chemical transport model simulations), calibrated predictive maps of PM 2.5 levels were linked to each participant's residential zip code as a proxy for exposure measurements.The researchers followed the individuals annually until their first hospitalization for any subtype of CVD.For exposure-response estimations, a causal framework was developed against confounding bias and bias resulting from errors in exposure measurements.Both relative and absolute effects were assessed.• Three-year average exposure to PM 2.5 was associated with increased relative risk (RR) of first hospital admissions for IHD, cerebrovascular disease, HF, CMP, AR, and AA.Ischaemic heart disease was the most prevalent CVD resulting in hospitalization (8.8%) followed by cerebrovascular disease (7.7%), HF (6.6%), and AR (6.5%).Notably, the curve for HF showed the steepest slope, with the RR for a first hospitalization ranging from 1.19 [95% confidence interval (CI), 1.17-1.22]for the exposure interval 5-6 µg/m 3 to 2.31 (95% CI, 2.28-2.35)for the highest exposure interval (>14 µg/m 3 ).• Overall, 22% of subjects had a composite CVD-related hospital admission.No safe threshold for chronic exposure to PM 2.5 was identified.The exposure-response curve showed a monotonic increase in risk associated with PM 2.5 .Compared with the lowest exposure interval ≤ 5 µg/m 3 [World Health Organization (WHO) air quality guidelines], the RR of hospital admission was already raised for exposures between 5 and 6 µg/m 3 .The RR for exposures between 9 and 10 µg/m 3 , which included the US national average of 9.7 µg/m 3 during the study period, was 1.29 (95% CI, 1.28-1.30).On an absolute scale, the risk of hospitalization for composite CVD increased from 2.6% with exposures ≤ 5 µg/m 3 to 3.4% for exposures ranging between 9 and 10 µg/m 3 and then up to 4.7% for the highest levels of exposure (>14 µg/m 3 ).The effects persisted for at least 3 years after exposure to PM 2.5 .Age, education, accessibility to healthcare facilities, and the level of neighbourhood-related deprivation appeared to have an impact on susceptibility to PM 2.5 .