Long-term exposure to traffic emissions and fine particulate matter and lung function decline in the Framingham heart study

Abstract

Rationale: Few studies have examined associations between long-term exposure to fine particulate matter (PM2.5) and lung function decline in adults.

Objectives: To determine if exposure to traffic and PM2.5 is associated with longitudinal changes in lung function in a population-based cohort in the Northeastern United States, where pollution levels are relatively low.

Methods: FEV1 and FVC were measured up to two times between 1995 and 2011 among 6,339 participants of the Framingham Offspring or Third Generation studies. We tested associations between residential proximity to a major roadway and PM2.5 exposure in 2001 (estimated by a land-use model using satellite measurements of aerosol optical thickness) and lung function. We examined differences in average lung function using mixed-effects models and differences in lung function decline using linear regression models. Current smokers were excluded. Models were adjusted for age, sex, height, weight, pack-years, socioeconomic status indicators, cohort, time, season, and weather.

Measurements and main results: Living less than 100 m from a major roadway was associated with a 23.2 ml (95% confidence interval [CI], -44.4 to -1.9) lower FEV1 and a 5.0 ml/yr (95% CI, -9.0 to -0.9) faster decline in FEV1 compared with more than 400 m. Each 2 μg/m(3) increase in average of PM2.5 was associated with a 13.5 ml (95% CI, -26.6 to -0.3) lower FEV1 and a 2.1 ml/yr (95% CI, -4.1 to -0.2) faster decline in FEV1. There were similar associations with FVC. Associations with FEV1/FVC ratio were weak or absent.

Conclusions: Long-term exposure to traffic and PM2.5, at relatively low levels, was associated with lower FEV1 and FVC and an accelerated rate of lung function decline.

Keywords: air pollution; asthma; chronic obstructive pulmonary disease; particulate matter; respiratory function tests.

Figure 1.

Differences in average lung function (and 95% confidence intervals) by distance-to-roadway category compared with the 400- to 1,000-m reference group. Adjusted for sex, age, height, weight, pack-years, education (no high school diploma, completed high school, some college, college degree or higher), median household income from 2000 census tract, cohort, date of examination, weekday, season (as a sine and cosine function of date), and relative humidity and temperature the day before the examination.

Figure 2.

Differences in the rate of change in lung function (and 95% confidence intervals) by distance-to-roadway category compared with the 400- to 1,000-m reference group. Adjusted for sex, age, height, weight, pack-years, education (no high school diploma, completed high school, some college, college degree or higher), median household income from 2000 census tract, cohort, date of examination, weekday, season (as a sine and cosine function of date), and relative humidity and temperature the day before the examination.