The objective is to find any correlations between meteorological factors and air pollution levels in Bishkek, Kyrgyzstan.
What is a Particulate Matter?
#Source: https://en.wikipedia.org/wiki/Particulates
Atmospheric particulate matter (PM) are microscopic particles of solid or liquid matter suspended in the air. The term aerosol commonly refers to the particulate/air mixture, as opposed to the particulate matter alone. Sources of particulate matter can be natural or anthropogenic. They have impacts on climate and precipitation that adversely affect human health, in ways additional to direct inhalation.
Types of atmospheric particles include suspended particulate matter; thoracic and respirable particles; inhalable coarse particles, designated PM10, which are coarse particles with a diameter of 10 micrometers (μm) or less; fine particles, designated PM2.5, with a diameter of 2.5 μm or less; ultrafine particles, with a diameter of 100 nm or less; and soot.
Why high concentration of pollutants (PM, Nitrogen Oxides, SOx, etc.) in air is dangerous for health?
#Source: https://ww2.arb.ca.gov/resources/inhalable-particulate-matter-and-health
Both PM2.5 and PM10 can be inhaled, with some depositing throughout the airways, though the locations of particle deposition in the lung depend on particle size. PM2.5 is more likely to travel into and deposit on the surface of the deeper parts of the lung, while PM10 is more likely to deposit on the surfaces of the larger airways of the upper region of the lung. Particles deposited on the lung surface can induce tissue damage, and lung inflammation.
#Source: https://en.wikipedia.org/wiki/Particulate_pollution
Living under high concentrations of pollutants can lead to headaches, fatigue, lung disease, asthma, and throat and eye irritation. One of the most common diseases among those living among pollutants is chronic obstructive pulmonary disease (COPD). Exposure to wood and charcoal smoke is significantly associated with COPD diagnoses among those living in developing and developed countries. Exposure to woodsmoke intensifies the respiratory systems and increases the risk of hospital admissions.
(Direct quotations from the research are translated using DeepL. Thank you DeepL:))
The research provides information on the broad number of topics related to the problem of poor air quality levels in Bishkek; such as major sources of air pollution, policy framework for air quality management, affects of air pollution on human health, scientific rationale of the problem, etc. Further, we will mainly focus on the exploration of scientific review.
The influence of meteorological factors on air quality is touched upon in the research. Therefore, we can highlight key takeaways:
#WindFactor #PBL
Wind rose: frequency of winds recurrence on the sides of the horizon (in percent) in Bishkek.
The dispersion of air pollutants occurs mainly in the lower part of the atmosphere, called the planetary boundary layer. The height of the boundary layer determines the volume of air in which emitted pollutants can disperse and mix with the air. The greater the boundary layer height, the better the mixing conditions for pollutants. The height of the boundary layer varies depending on meteorological conditions and the time of year. During night and winter, when solar radiation is absent or insignificant, the boundary layer height is usually less than 200 meters, but in summer it can reach more than 500 meters. The wind regime of the boundary layer roughly determines the direction of transport of pollutants in the air, but the turbulence of the air currents in the boundary layer and its height significantly influence the direction of transport of pollutants in the air. The wind regime of the boundary layer roughly determines the direction of pollutant transport in the air, but air turbulence in the boundary layer and its height significantly influence the mixing of pollutants and dilution of their concentrations. Thus, the key meteorological variables for the dispersion of pollutants are the direction and velocity of the boundary layer. The key meteorological variables for pollutant dispersion are wind direction and speed, a value characterizing the stability of the atmosphere, and the height of the mixing layer.
Meteorological conditions of air mass mixing in Bishkek by months:
Since no radiosonde data were available, the vertical profiles of temperature and wind were estimated from surface observations. Air mass mixing in Bishkek is generally weak, 50 percent of the time in the summer season and more than 85 percent of the time in the winter season.
Distribution of boundary layer height in Bishkek by months:
The figure shows that the height of the mixing layer in Bishkek in January and December ranges from 100 to 200 meters in 80 percent of cases. Weak mixing of air masses and low mixing layer heights cause higher air pollution levels in winter, as the volume in which air can mix is smaller than at other times of the year. Emissions from the ground also tend to be higher in winter, further degrading air quality. Periods of strong to moderate air mass mixing increase during the spring months, and the best conditions occur during the summer months. The figure does not contain 59 data for mixing layer heights less than 100 meters. This is due to the lack of sounding data in the Bishkek area. The lowest heights of the mixing layer cannot be determined by the calculation method, which is based on wind measurements from meteorological stations in Bishkek. For a more detailed vertical profile of the atmosphere, sounding data are needed.
In Bishkek, the proximity of mountains affects meteorological conditions of atmospheric air mixing in different ways. of atmospheric air. Mountains can cause thermal inversion, in which cold air descends from higher elevations and causes a decrease in the height of the boundary layer. This can lead to higher concentrations of pollutants near the surface as air pollution is trapped in smaller air masses. Mountains can also block winds and thus worsen air mixing conditions. In addition, orographic precipitation falls in the mountains south of Bishkek. Most of it falls on the windward (in this case southern) side of the mountains, while the leeward side tends to remain dry. Orographic precipitation decreases relative humidity and increases temperature on the dry side of the mountains. Because Bishkek receives less precipitation due to the proximity of the mountains, air quality is worse than in the flatlands, as precipitation clears the atmosphere of pollutants through wet deposition.
"Current climate of Bishkek, Chui Valley and the Northern Slope of the Kyrgyz Ridge" by O.A. Podrezov
(Direct quotations from the climate manual are translated using DeepL. Thank you DeepL:))
In this collection of studies O.A. Podrezov and his colleagues have researched geographical and climate peculiarities of Bishkek, the Chui Valley and the northern slope of the Kyrgyz Ridge framing it from the south.
Moreover, author has touched upon the problem of atmospheric air pollution of Chui valley cities. Therefore, we can highlight key takeaways:
#MeteorologicalFactors #WindFactor #PrecipitationFactor
The atmosphere of the Chui Valley, especially the atmosphere of its cities, as well as of Central Asia as a whole, is characterized by a high level of pollution. Dry, hot summer climate with surrounding deserts and semi-deserts predetermine a large natural dustiness of the atmosphere. This is overlaid by significant anthropogenic emissions from motor transport, thermal power plants, various industrial enterprises and the household sector.
Meteorological conditions favorable for atmospheric pollution are weak winds or calm winds, fogs, temperature inversions (when it increases with altitude, preventing vertical mixing) and absence of precipitation that washes out impurities. Impurities are fairly well dispersed in the atmosphere and it is self-cleaning at higher wind speeds (more than 5-6 m/s) and heavy precipitation when it exceeds the lower threshold value of 0.5 mm.
Here we can ask stupid and brave, where one does not exclude another, questions; as such questions might lead us to something new and unknown.
In his studies O.A. Podrezov has mentioned weak or calm winds as one of the meteorological conditions, which contribute to air pollution; while classifying high wind speeds as one of the factors relevant to dispersion of impurities in the air. Further, based on the nature of ventilation of planetary boundary layer, we can argue that winds heavily influence the quality of the air we breathe.
In further questions we will try to provide numerical representations of the correlation, if any, between wind and air pollution. However, one has to understand imprecisions of the analysis, as the consequence of the following reasons:
- limited set of data;
- constraints put by the difference in locations of weather and air quality stations. You can find the data files used for analysis here.
In his collection of studies O.A. Podrezov has mentioned a threshold for the wind speed, for which impurities in the atmosphere are fairly well dispersed, that is above 5-6 m/s (18-21.6 km/h).
Here we would like to investigate the effect that all of the spectrum of wind speeds in Bishkek has on raw concentration of PM2.5 in the air. We will look whether there are any reductions in concentration of PM2.5 in case of winds of varying speeds.