Benz(a)pyrenes are aromatic polycyclic hydrocarbons. In the pictures in school chemistry textbooks they are depicted as a group of benzene rings linked together. The compounds belong to substances of the 1st hazard class, since they are carcinogens and provoke the development of cancer.
Sources of the formation of benz (a) pyrene:
industries associated with the combustion process, smoldering urban landfills;
The substance is also formed during the frying and smoking of products.
To determine the concentration of the substance in the laboratory, an analysis of the air for the presence of this carcinogen is carried out, food products are examined. If indicators of a toxic substance exceed the maximum permissible concentrations, measures are being developed to improve working conditions and reduce atmospheric emissions.
Benzene (a) pyrene accumulates in the human body, so getting it even in small doses is dangerous to health. Under the influence of a carcinogen, cells begin to abnormally divide, causing cancerous tumors. Other manifestations of negative effects on the human body:
the development of vascular atherosclerosis;
strokes and heart attacks.
The degree of danger of poisoning by a substance does not depend on how it got into the body. Non-smoking people, adherents of a healthy lifestyle are not excluded from the risk zone, as they can breathe air with exhaust fumes.
The fact of bioaccumulation of benz (a) pyrene is proved. The substance has the ability to integrate into DNA strands, cause gene mutations that can manifest itself after several generations.
There are no methods to cleanse the body of this toxic substance. But you can avoid its harmful effects:
limit the consumption of smoked and fried foods, canned foods;
be interested in the concentration of the substance in the air of the working area, near the place of residence.
Researchers from Canada found that a high concentration of ultrafine particles in the air, which are formed as a result of combustion processes, especially diesel fuel, increases the risk of developing tumors in the brain.
Emissions from plants affect lung cancer incidence. The composition of these emissions includes ultrafine particles. Scientists have recently begun to study the effect of these particles on the brain.
Specialists from McGill University analyzed the data of 2 million people from Montreal and Toronto from 2001 to 2016 who were diagnosed with a brain tumor. They looked in the area in which these people lived, as well as how the ultrafine particles were distributed on the ground.
Respondents who were most exposed to ultrafine particles have a greater risk of developing a brain tumor than people who have undergone minimal exposure. Scientists believe that increasing the concentration of these particles in the air on a global scale will increase the number of cancer cases, reports Epidemiology.
It is an air pollutant that contains both solid microparticles and tiny droplets of liquids. Both those and the size of about 10 nm to 2.5 microns. Other designations and names of PM2.5 particles: FSP (fine suspended particles), fine particles, fine particulate matter, fine suspended particles, fine dust.
By source type, PM2.5 particles are divided into:
The main anthropogenic source of particles is transport. Internal combustion engines and industrial processes with the burning of solid fuels (coal, brown coal, oil), construction, mining, many types of production (especially the production of cement, ceramics, brick, smelting), in cities the source may be road surface erosion and erasing brake pads and tires. Even agriculture is a source of ammonia, from which secondary PM2.5 can form.
Sources: soil erosion in arid areas and organic fumes.
Mass concentration of PM2.5 is a key parameter for assessing air quality and its threat to human health. According to the standards of the World Health Organization (WHO), the average annual level of PM2.5 should be no more than 10 μg / m3
In urban air, in principle, there are many different particles: small and large, light and heavy. Only heavy particles "fall" to the ground over time (remember the black snow next to some plant), and light PM2.5 practically do not settle. It is more difficult for small particles to overcome the resistance of the medium and "fall" to the ground. And for the smallest particles, the Brownian motion also exerts resistance.
|diameter, um||míra vypořádání/ settling rate, m/sek|
As can be seen from the table, for PM2.5 particles, the sedimentation rate is 15 times lower than for PM10 and is approximately 0.2 mm / s. This value is compensated even by a slight upward flow of air. And for the so-called PM0.1 ultrafine particles (with a diameter of up to 0.1 μm), the Brownian motion completely prevails over the sedimentation rate. Therefore, this smallest fraction of particles can never settle at all.
PM2.5 particles are also called respirable, respirable fraction. They are so small that they pass through biological barriers in our body: nasal cavity, upper respiratory tract, bronchi. PM2.5 together with air enter directly into the alveoli - vesicles in which gas exchange occurs between the lungs and blood vessels.
Úroveň CO2 ve vzduchu se měří pomocí jednotky ppm (parts per million).
350 - 450 ppm hodnota totožná s běžným vnějším prostředím
do 1000 ppm doporučená úroveň CO2 ve vnitřních prostorách
1200 až 1500 ppm doporučená MAXIMÁLNÍ úroveň CO2 ve vnitřních prostorách
nad 1500 ppm nastávají příznaky únavy, snižování koncentrace, bolest hlavy
nad 5000 ppm maximální bezpečná koncentrace bez zdravotních rizik
více než 5000 ppm nevolnost a zvýšený tep
více než 15000 ppm dýchací potíže
více než 40000 ppm možná ztráta vědomí
The level of CO2 in the air is measured by ppm (parts per million).
350 - 450 ppm value identical to normal external environment
Up to 1000 ppm recommended CO2 level indoors
1200 to 1500 ppm recommended MAXIMUM CO2 level indoors
Over 1500 ppm there are signs of fatigue, decreased concentration, headache
Above 5000 ppm maximum safe concentration without health risks
More than 5000 ppm nausea and increased heart rate
More than 15000 ppm respiratory problems
More than 40,000 ppm possible loss of consciousness
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