Environmental Factors: Air

Air is a mixture of gases; it consists mostly of nitrogen (78%) and oxygen (21%). In addition, there are the noble gas argon (0.9%) and carbon dioxide (0.04%), as well as smaller amounts of other substances (e.g. radon* , nitrogen oxides, etc.). * Other sources of radon are drinking water and natural gas; see below S1 Guideline: Environmental Medicine Guideline Radon in Indoor Areas The greatest change in air composition is the increase in carbon dioxide content. The concentration of CO2 has increased since about 1850 from 280 ppm (parts per million) to 407.8 ppm (particles per million particles). The World Meteorological Organization (WMO) reported in its 2019 annual greenhouse gas bulletin that CO2 concentrations have increased from 405.5 ppm to 407.8 ppm within a year. Responsible for the increase in carbon dioxide is:

  • Fossil fuel combustion (coal, oil, gas, gasoline).
  • Deforestation

Any substance that is not part of the natural composition of the air is called a pollutant. The following pollute the air or are considered air pollutants:

Gases

  • Carbon dioxide (CO2)*
  • Carbon monoxide (CO; colloquially known as carbon monoxide).
  • Methane
  • Nitrogen oxides (NOx)
  • Nitrogen dioxide (NO2)
  • Sulfur oxide
  • Benzene
  • Fluorocarbons
  • Chlorofluorocarbons (CFCs)
  • Sulfur hexafluoride
  • Ozone (O3)*

* Is a natural component of the air, but contributes to pollution by increasing! Fine dust / particles

  • Ash, soot
  • Dust – especially fine dust (road traffic – esp. diesel particles; toner from laser printers).

In 2015, air pollution caused 8.8 million premature deaths worldwide. This corresponds to an average reduction in per capita life expectancy of 2.9 years.

Gases

For indoor air quality (indoor air), only carbon dioxide (CO2), which is easy to determine, is usually measured. The goal is to not exceed a CO2 level of 800-1,000 ppm. 1,400 ppm is the upper limit for acceptable indoor air. For this to be achieved, ventilation must normally be active for 5-15 minutes every 2 to 4 hours. For outdoor room quality (outside air), nitrogen dioxide (NO2) is usually measured. In summer as well as in winter, so-called smog occurs, especially in large cities, due to the low wind conditions and dense population. This refers to air pollution and is caused, among other things, by exhaust gases from means of transport, combustion power plants (emissions) and UV radiation. Two-thirds of the main source of nitrogen dioxide (NO2) in Germany is road traffic. Three quarters of the nitrogen dioxide comes from the exhaust of diesel passenger cars. The EU limit value for nitrogen dioxide in outdoor air is 40 micrograms per cubic meter. Smog contains numerous pollutants in high concentrations that can be particularly dangerous for obese people, the elderly and children. These include sulfur dioxide, sulfurous acid, nitrogen dioxide, carbon monoxide, hydrogen peroxide and methane. Obese people show a decrease in lung function (decrease in one second capacity (FEV 1) and vital capacity (FVC)) with increasing concentrations of nitrogen dioxide and particulate matter in outdoor air. Smog and high ozone levels can lead to the following diseases or medical conditions:

Air pollution is especially hard on people with obesity (overweight). The risk of infants to develop sensitization to common everyday allergens in the first year of life increases with nitrogen dioxide pollution from outdoor air, according to the Canadian Healthy Infant Longitudinal Development Study (CHILD). Smog (particulate matter, nitrogen dioxide, sulfur dioxide) is further associated with apoplexy (stroke). Elevated nitrogen dioxide and particulate matter levels appear to be associated with increased myocardial infarction (heart attack) rates. Increased nitrogen dioxide pollution makes pollen of the ragweed (Ambrosia artemisiifolia) more aggressive, i.e. particularly large amounts of allergen are formed. The pollen of such plants also binds particularly strongly to specific IgE antibodies of ragweed allergy sufferers.

Particulate matter/fine dust

Particulate matter is defined as particles with a size of less than ten micrometers. Particulate matter with a diameter of less than 2.5 micrometers is considered particularly hazardous to health because it penetrates deep into the lungs as “respirable fine dust.” After inhalation, the fine dust enters the blood within a few hours, where it can still be detected three months later. The particles are taken up by the liver and accumulate in atherosclerotic lesions. Particulate matter in an overview

Particulate substances Abbreviation Description
Fine dust PM10 Particles with an aerodynamic diameter < 10 µm (measured as mass).
Fine particles PM2.5 Particles with an aerodynamic diameter < 2.5 µm (measured as mass)
Ultrafine particles UFP Particles with an aerodynamic diameter < 100 nm (measured as number).

If the average particulate matter load had been elevated throughout pregnancy, this resulted in a 19% increase in the risk of preterm birth. If the average particulate matter load during the third trimester (third trimester of pregnancy) was 15 µg/m3 or higher, preterm births occurred 28% more frequently.Women exposed to higher concentrations of respirable particulate matter during pregnancy gave birth to an above-average number of infants with a birth weight of less than 3,000 grams. The study examined 1,016 mothers and their children born in Munich between 1998 and 1999. Data from measurements at 40 locations in Munich confirmed the mothers’ exposure to traffic-related air pollutants, including respirable fine dust particles. People who live near busy roads are more likely to develop atherosclerosis. The cause of this has now been found by scientists at the University of California, Los Angeles (UCLA). In an in vitro experiment, they combined particles from diesel exhaust and the fatty acids found in LDL cholesterol, along with cells from the inner lining of human blood cells (endothelium). A few hours after the start of the experiment, the DNA of the cells was analyzed. The result showed that the genes that promote inflammation at the cellular level had been activated, i.e. switched on. Type 2 diabetes mellitus is also more common with exposure to particulate matter. Chronic inflammation is blamed for this. Likewise, the risk of coronary disease increases with long-term exposure to particulate matter. Long-term concentration of particulate matter is associated with the risk of apoplexy (stroke) and coronary event (e.g., myocardial infarction) independent of residential noise exposure. Fine particulate matter (PM2.5) and other air pollutants (nitrogen dioxide (NO2)) are associated with risk of hypertension (high blood pressure). Higher levels of particulate matter (PM2.5) were associated with a 4 percent increased risk of fracture (bone fracture risk). Particulate matter increases the risk of bronchial asthma: hazard ratio of 1.05 (1.03 to 1.07) for each 5 µg/m3 increase in particulate matter (PM2.5) concentration and of 1.04 (1.03 to 1.04) for a corresponding increase in PM10 concentration. People exposed to particulate matter from traffic exhaust over a long period of time (study duration: > 20 years) have an increased mortality risk (risk of death), even if concentrations are well below the currently applicable EU limits. A study of nearly 61 million people living in 39,716 locations in the United States demonstrated that exposure to particulate matter less than 25 μm in size (PM25) and ozone concentrations between 36.27 and 55.86 ppb leads to an increase in mortality (death rate):

  • With each 10 μg/m3 increase in PM25 exposure, mortality increases by 7.3% (95% confidence interval (CI) 7.1-7.5)
  • With each increase in ozone exposure of 10 ppb, mortality increases and 1.1% (CI 1.0-1.2)

Exposure to particulate matter (PM10 or PM2.5) increases mortality (mortality) even in the short term: increase in 2-day average PM10 concentration by 10 µg/m3 was associated with an increase in same-day all-cause mortality by 0.44% (95% confidence interval 0.39-0.50%). Particulate matter and ozone increase mortality risk (risk of death) in the elderly even below the applicable limits. Conclusion.Diesel particles, which are usually also coated with chemicals, can cause tissue damage and inflammation of the nose and lungs. Furthermore, they can lead to vascular inflammation, which in turn can be the cause of myocardial infarction (heart attack) and apoplexy (stroke). Another disease caused by diesel dust is coronary heart disease (CHD). Ischemic and thrombotic mechanisms are thought to be responsible for this. Increased exposure to particulate matter from road traffic in London during pregnancy increased the risk of deficient birth in a population-based cohort study. The number of infants who had low birth weight (LBW) or were too small for their gestational age (SGA) was associated with exposure to particulate matter: a 2-6% increased risk of LBW birth and a 1-3% increased risk of SGA birth. Of note, the average level of particulate matter in London’s air in 2006 and 2011 was 14 µg/m3 (and thus below the applicable EU limits of 25 µg/m3); some neighborhoods had levels significantly above this.

Household sprays

For household sprays, there is a clear dose-response relationship for the risk of bronchial asthma: people who used household sprays at least once a week had half the risk of asthma compared with participants who did not; four times a week use of household sprays already doubled the risk of asthma!