Climate National Centre, Meteorological Institute, Havana, Cuba. ABSTRACT. In this paper is shown the values obtained from the air quality in an experimental ...
AIR QUALITY COMPARATION IN OUTDOOR AND INDOOR ENVIRONMENT IN HUMID TROPIC (CUBA) O. Cuesta-Santos1, M. González1, P. Sánchez1, A. Collazo1, A. Wallo1, A. Guevara2 1 2
Atmospheric Environment Research Centre, Meteorological Institute, Havana, Cuba Climate National Centre, Meteorological Institute, Havana, Cuba
ABSTRACT In this paper is shown the values obtained from the air quality in an experimental way in a zone of Havana City with strong industrial influence and motor traffic. The levels of SO2 and the Total Suspended Particles (TSP) are one-third superior in outdoor environment. While NO2, NH3 and H2S registered higher values in indoors. The concentration of SO2 and the TSP surpass in this zone the maximum admissible concentration according to the Cuban standards and the recommended criteria by the Health World Organisation. In this zone the prevalence of affected people by respiratory infections (bronchial asthma) is higher than the city values. The meteorological variables, relative humidity and temperature, showed values slightly higher in indoor environment. While the wind speed was approximately twice higher in outdoors.
INTRODUCTION In the wet tropic as a general rule the constructions are designed to obtain adequate ventilation and achieve an acceptable indoor comfort for the high temperature and humidity conditions. In these cases the problems of existing air pollution in human settlements due to the emissions of industries and vehicle pollution travel with greater ease toward the indoor environments with their harmful effects on the human health and to the environment. The requirements to be satisfied in the design and construction of a building in a warm-wet climate are the following: Provision of continuous and efficient ventilation; protection against the sun and the rain; prevention of internal temperature elevation during the day and minimization during the evening and night [1]. The heat capacity of the building should be as low as possible in order to prevent accumulation of heat during the daytime, which would elevate the indoor temperature during the night when the external wind speed is usually at its lowest values. One disadvantage of ventilated buildings in tropical regions is the penetration of the external pollutants and the heating of the internal mass of the building by the outdoors warn air, with consequent higher indoor temperatures at night. The situation is different in buildings where a high level of daylighting is required, such as schools, offices, etc; there the windows have to be much larger than in residences. Indoor temperature cannot be reduced below that outdoors on account of the considerable heat gained through the windows, and in most cases they are even higher.
The predominance of high humidity necessitates a correspondingly high air velocity to increase the efficiency of sweat evaporation, and to avoid as far as possible the discomfort due to moisture on skin and clothes. This paper intends to know in a experimental way the behaviour of the principal variables of the indoor and outdoor atmospheric environment of an educational building set in a residential zone with antropic strong influence. As well as the possible impacts which can be derived from this influence. METHODS AND MATERIALS The experiment is developed during a month in the high-school building whose construction is characterised by wide windows and doors in its frontal part and an open interior courtyard, which permits good ventilation. Generally the constructions in the wet tropic possess wide windows and doors to improve the ventilation in order to mitigate the effect of the high temperatures and humidity. The outdoor place of measurement was in the sidewalk, out of the high-school "Julio A. Mella", at a meter of distance of the street and at 1,5 meters of height. The indoor place of measurement was located in the open interior courtyard next to the classrooms. The height of the sampling was equal to outdoor point. This school is located in Regla town, in the City of Havana. This town is at the South Southeast side of the bay of the Havana, a port and industrial zone (Figure 1).
Figure 1. Map of measurement zone and pollution sources In its margins, two-power station and an oil refinery are seated, as well as other small industries, which also contribute with their emissions to the air pollution. Narrow streets characterise this urban sector and it is a zone located within few meters on the mean sea level (MSL), something that facilitates the accumulation of pollutants when there are light wind and calms [2]. The proximity of these potent source pollutants, as well as the increase of the vehicle circulation and the density of the population, makes zone of the most contaminate within Havana City [3].
The pollutants studied were the SO2, NO2, NOx and Total Suspended Particles (TSP) which are among the principal pollutants studied in urban zones, in addition to H2S and the NH3, whose emissions exert important effects in the studied zone. Daily samples were taken. The obtained values from the measurements and chemical analysis of the evaluated pollutants were accomplished according to the methodologies of the Atmospheric Environment Research Centre (AERC) of the Meteorological Institute. In general the recommendations of the World Health Organization (WHO) and the World Meteorological Organization (WMO) for the sampling, chemical analysis and processing of the information [4,5,6] govern those. The data on meteorological variables, obtained with calibrated equipment were taken following the prescriptions existing for their allocation, so that they will be representative of the mean characteristics [7,8]. The measurements were taken in a continuous way. RESULTS AND DISCUSSION For the principal pollutants in urban zones, the SO2, NO2 and TSP it was found (Figure 2 and 3) that in outdoor environments the concentrations are greater than indoor environments. Although a great difference does not exist, due to the good ventilation characteristics previously mentioned of the constructions in warm-wet climate. On the other hand the NH3 and H2S present highest concentrations in indoor conditions. Everything seems to indicate that the concentrations of these pollutants in the indoor environment increase due to biogenic emissions related with the human being and their waste.
300,00
250,00 C(µ g/ m 200,00 )
3
150,00
100,00
Outdoor
50,00
0,00
Indoor SO2 H2S TSP
Figure 2. Outdoor and Indoor measurements of Sulphur's Compound and TSP
In both environment the admissible maximum concentrations established in the Cuban Standard for the SO2 and TSP are surpassed, something motivated by the nearness of potent sources of these pollutants. In the case of SO2, the value of Cuban standard (50µg/m 3) was overcame the 62% of the total of samples considered in the experiment, while WHO
criterion were overcame in more than of 50% of the cases. For TSP, the Cuban Standards (150µg/m 3), was overcame by the 67% of the cases. These high concentrations can provoke various injurious effects on health. According to the World Health Organization (WHO), people living in areas where the level of SO2 is of 100 µg/m 3, a present pulmonary functions that are worse on the averages in 4 - 7% that those of a population in places where the concentration is of 50 µg/m 3 [5]. Also when concentrations of TSP are over 100 µg/m 3 give as a result increases of respiratory sickness in children.
30,00
C( µg/ 25,00 m3 )
20,00
15,00
10,00 Indoor 5,00
0,00
Outdoor NO2 NOX NH3
Figure 3. Outdoor and Indoor measurements of Nitrogen's Compound
In subtropical climate countries, the found results in outdoor environments are bad indicators of expositions, due to people stay most of the time in indoor environments [9,10]. In Cuba, this relationship is much better because there are less differences between outdoor and indoor environments. Bronchial Asthma in Cuba is characterised by a prevalence of 8.58% in urban zones, 7.5% for rural zones and 8.2% for the total population. Another aspect in Bronchial Asthma is that occupies 13.6% of all the urgencies in the hospitals; in the case of children it is 6.8% [11]. This disease is a health problem in Cuba. In developed countries, the number of bronchial asthma medical consult oscillates among 20-40% of the total of all the medical consults offered in Children's Hospital. In our studied zone, we have that bronchial asthma presents a prevalence of 10,0%. These values reflect a higher incidence than the reported average for urban zones. This is something, which can be attributed among other causes to greater air pollution. This information was gathered through Health System of the Family's Doctor.
Specifically in the Family's Doctor zone, where J.A. Mella High School is there exists a prevalence of 10,2% of bronchial asthma and in the nearest clinic to Regla's power station, the percent of asthmatics is 13,1. This greater incidence can also be attributed to the deterioration conditions of air quality. As it is seen in Table 1, temperature and relative humidity are slightly higher in indoor environment. While wind speed is approximately twice higher in outdoor environment. Table 1. Values of meteorological variables Variable Temperature (Celsius degree) Relative humidity (percent) Wind speed (meter per second)
Indoor
Outdoor
29,9 79 0,8
27,9 78 1,7
These differences are stressed during the night when temperature and relative humidity tend to increase in indoor environment. As a general rule, only in hours of the morning and early in the afternoon the temperature and relative humidity were less high in the indoor environment. For the study of the influence of the atmospheric environment on human being are used different bioclimatic indexes that have a complex character, since they link two or more climatic elements [12,13]. Effective Temperature (ET) or index of lack of comfort, is one of them, it is used for indoor conditions evaluation and do it includes temperature and relative humidity. Calculations of the effective temperature permitted to know that during the experiment in outdoor environment, thermal comfort sensation was distributed in the following form: 7% very warm sensation, 83% warm sensation and 10% comfortable sensation. On the other hand, indoor environments obtained that 60% of the time very warm sensation and 40% warm sensation, without the presence of comfortable sensation. The studies related to the air quality and the climate in Cuba indoor environments should be followed in order to project a fitting environmental policy. These experimental studies are very important to improve living conditions in schools, offices and residences. The air quality is also important to rise the people standard of life. ACKNOWLEDGEMENTS We want to thank Education Ministry Delegation and local government, by the facilities offered for the execution of this paper, as well as to the Environment Agency by the granted financing.
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