The Health Consequences of Exposure to Fine Particulate Matter

Though heavy air pollution in Germany is a thing of the past, even today the air quality threshold in the country exceeds. Solutions discussed include bypass roads, low emission zones, personal lifestyle interventions, industrial restrictions, etc. Further, a significant change in the quality of air pollution exists due to several factors including effective filtering of larger particles. This has caused a relative increase in smaller reparable particles.

Numerous studies revealing the adverse health effects caused by these particulate matter made the U.S. Environmental Protection Agency to reconsider its standards in 2013. Thus, the long-term threshold for reparable particulate matter with an aerodynamic diameter below 2.5 µm (PM2.5) was reset as 12 µg/m3 from 15 µg/m3. The roughly comparable value in the European Union (EU) is 25 µg/m3 now.
Though many researches in the recent years have reported associations between air pollution and total mortality along with respiratory and cardiovascular mortality, the correlation with stroke incidence has been researched less and has generated conflicting results. Further, many studies have revealed a correlation between cardiovascular disease and chronic noise exposure, which frequently co-occur with high degree of air pollution. However, studies investigating both air pollution and noise exposure are rare.

This concept deserves global attention from both public health and research communities because of its big relevance to human population. The EU funded a huge multicenter study called the European Study of Cohorts on Air Pollution Effects (ESCAPE) to examine the health impact of long-term exposure to the current concentrations of air pollutants in Europe.

The current study, known as the German Heinz Nixdorf Recall (HNR), has been based on ESCAPE, and done by Barbara Hoffmann and her coauthors in Deutsches Ärzteblatt International. It sought to find the long-term air and noise pollution on coronary events and stroke in the German Ruhr region.

The participants and methods
The cohort research, which was conducted from 2000 to 2003, studied the effect of long-term exposure to fine-particle dust (carbon black content) and traffic noise on the Ruhr population. The important sources of particulate matter are agriculture, industry, traffic, earth crust material and heating.

Over 4400 residents, aged between 45 and 74 years, from Mülheim an der Ruhr, Essen and Bochum participated in the study. Land-use regression and dispersion models were used to determine the fine-particle dust (PM10 and PM2.5) and traffic noise, respectively, at the home addresses of the participants. Patient records were used to ascertain events of coronary diseases and strokes annually. Cox regression analysis was used to calculate the adjusted hazard ratio (HR) for a hike in concentration from the 5th to the 95th percentile for each exposure.

Results and discussion
Air pollution concentration currently in Germany is only about a quarter of what it was in the 1970s. Even in today’s lower pollution concentration, the current study shows a correlation between long-term air pollution and stroke irrespective of noise pollution’s presence. It has been found that stroke incidence occurs with PM10 and PM2.5, the two PM fractions regulated currently EU wide. Additionally, the particulate dust’s soot content also seems to be connected with risk of both coronary and stroke events.
There was less clear results for coronary events, and no clear effect for exposure to noise pollution. Stroke incidence was 2.03 per 1000 person-years (PY), and coronary events incidence was 3.87 per 1000 PY. However, the data suggests a likelihood for increased risk of cardiovascular disease through particulate matter exposure, says the authors.
The suspected biological etiologies are direct impacts from absorbed pollutants, systemic and pulmonary inflammation, endothelial dysfunction and vasoconstriction, oxidative stress, prothrombotic changes, and autonomic nervous system imbalance. Early subclinical effects were systemic and pulmonary markers of inflammation, and increased blood pressure. Further, accelerated atherosclerotic progression, impaired pulmonary function, and worsened glucose metabolism were also present. Short-term increases to particulate matter on a daily basis and long-term residential exposure to the same caused an increased mortality rate. Life expectancy also extends with decreased exposure to particulate matter.
There is a greater risk of stroke associated with long-term exposure to fine-particle matter, both PM2.5 and PM10, irrespective of the individual’s exposure to noise at his or her residence. And, though there are less clear results for coronary events, they still indicate an increased risk. So, concreted action is required across Europe to reduce further exposure to particulate matter.

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