Long-term exposure to airborne particulate matter of 1 μm or less and blood pressure in healthy young adults: A national study with 1.2 million pregnancy planners

No evidence exists concerning the effect of airborne particulate matter of 1 μm or less (PM₁) on blood pressure of young adults planning for pregnancy. We collected health examination information of about 1.2 million couples (aged 18–45 years) from a national birth cohort in China from Jan 1, 2013 to Oct 1, 2014 and matched their home address to daily PM₁ and PM_2.5 concentrations, which were predicted by remote sensing information. Generalized additive mixed models were used to analyze associations between long-term exposure to PM and blood pressure, after controlling for individual factors. A 10 μg/m³ increase in PM₁ was associated with increased systolic blood pressure (SBP) for 0.26 (95%CI: 0.24, 0.29) mmHg in females and 0.29 (95%CI: 0.26, 0.31) mmHg in males, respectively. PM₁ was also associated with increased DBP for 0.22 (95%CI: 0.20, 0.23) mmHg in females and 0.17 (95%CI: 0.15, 0.19) mmHg in males, respectively. Similar effects on blood pressure were found for PM_2.5, meanwhile, the effect of PM_2.5 on SBP increased with the scale of PM₁ included in PM_2.5 (p for interaction term <0.01). In summary, long-term exposure to PM₁ as well as PM_2.5 was associated with increased SBP and DBP of Chinese young adults planning for pregnancy.