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Environmental Quality

 

Air Quality

The analysis of environmental problems in the country shows a distinct relation between pollution, mountain geography, the size and dynamics of human settlements, and economic growth. Pressure generated by demographic and industrial concentration, plus a lack of integral planning for the use of land and it's resources has caused an environmentally unbalanced development.

Atmospheric pollution is a consequence of such type of development, and as an example of the influence of orographic conditions, it may be stated that over 60% of the nation's population reside in place located at more than 500 meters above sea level, where environmental conditions are least favorable. Three sections of the country produce 40% of the atmospheric emissions: the metropolitan area of the cities of Mexico, Guadalajara, and Monterrey. As to the first, the largest urban and industrial concentration, the growing use of motor vehicles, the existence of large eroded areas and seasonal farmlands, as well as excessive energy demand have all contributed to the detriment of air quality; in addition, the geomorphology of the region does not help to the circulation of pollutants, for in addition to being located over 2 000 meters above sea level it forms a closed valley, favoring the concentration of pollutants.

 

Table 3 Inventory of emissions, 1989 (percentages)
Sector	Sources	SO	NOx	HC	CO	TSP	Total
Energy	PEMEX	7.2	1.8	5.5	1.8	0.3	2.4
	Thermoelectric plants	28.3	3.7	0.0	0.0	0.8	1.6
Industry and Services	Industry	32.0	16.3	7.0	0.5	2.3	3.7
	Trade	10.7	2.2	0.0	0.0	0.5	0.7
Transport	Automobiles:
	Private	1.7	23.7	24.7	45.0	1.0	34.9
	Taxis	0.4	5.4	5.6	10.2	0.2	7.9
	Minivans and minibuses	0.4	5.7	7.5	13.7	0.2	10.5
	R-100	2.5	4.5	0.4	0.2	0.1	0.5
	Cargo trucks:
	State of Mexico	6.3	10.3	0.9	0.4	0.1	1.1
	Gsoline trucks	0.5	9.6	11.9	26.4	0.3	19.9
	Diesel	9.8	14.7	1.3	0.6	0.2	1.6
	Others	0.1	1.5	0.3	0.2	0.0	0.2
Ecological impairment	Erosed areas	0.0	0.0	0.0	0.0	93.1	9.6
	Fires and other processes	0.1	0.5	34.9	0.9	0.9	5.3
	Total	100.0	100.0	100.0	100.0	100.0	100.0
	Totales (ton/year)	205 725	177 339	572 101	2 950 627	450 599	4 356 391
Source: Integral Program against atmospheric pollution, technical intergovernamental secretariat, october, 1990

 

The other two urban areas are in similar, yet less dramatic, conditions. In Monterrey, industrial activity is represented by over 7 000 firms, and the utilization of non-metallic mineral resources has been decisive both in the development and in the pollution of the region.

Oil and docking industries in the Gulf of Mexico have brought important benefits to the country, however, the concentration of related activities has had a significant effect on the region. The same may be said for the industrial corridor of the Central Plateau and for the Tula-Vito-Apasco zone, where petrochemical industry and electrical energy generation have surpassed the environment's assimilation capacity,emitting 350 000 tons a year; the most abundant of these pollutants being sulfur dioxide and suspended particles (80 percent). The accelerated industrialization process in the border area of the north of the country has produced air related environmental effects, which are worth considering. Solid waste disposal is also of concern, for only 30% of all generated wastes are presently returned to their country of origin.

Furthermore, the creation of approximately 1 500 industries in the border area has prompted an accelerated demographic concentration that will generate new sources of pollution. A common factor in the deterioration of this area is a high fuel consumption for industrial, commercial and service purposes.

MEXICO CITY'S METROPOLITAN AREA (MCMA). Air pollution in this zone is a result of a high demographic concentration. It is important o consider that the MCMA houses more than 15 million people which generate over 36% of the country's national product, and consume 17% of the nation's electricity. An estimated 12 000 service establishments that use combustion and incineration processes operate in the MCMA.

The thermoelectric centrals of Jorge Luque and Valle de Mexico combined produce more than 9% of the total industrial, commercial, and service related emission of pollutants; production, storage, and distribution of fuels generate around 14% of the pollution from stationary sources, while motor vehicle pollution represents 76% of the total atmospheric emissions in Mexico City (Table 3).

Thermal inversion is one of the elements that more directly contributes to the accumulation of atmospheric pollutants; these occur practically every day of winter in the MCMA. Moreover, this season brings other meteorological phenomena that increase the concentration of pollutants, like the presence of high pressure systems that further limit their dispersion. The main pollutants in the metropolitan area of Mexico City are carbon monoxide, sulfur dioxide, nitrogen oxides, ozone, suspended particles, and lead.

The standards by which these pollutants are measured (table 4) were established by the health sector through a decree published on November 29, 1982. This decree considers man as the foundation and objective of these standards.

In order to evaluate air quality in the MCMA, a system of monitoring stations has been implemented; they form the Automatic Network for Atmospheric Monitoring (ANAM) and the Manual Atmospheric Monitoring Network. The first of these has 25 stations that evaluate seven pollutants and four meteorological parameters. The second comprises 19 stations that evaluate total suspended particles, or TSP (five), breathable suspended particles (BIP), 80)4, N03, and heavy metals (lead, cadmium, copper, zinc, and nickel). In order to enhance the ANAM's coverage, there is a financing project from the World Bank, to extend and reinforce the present network.

The SEDESOL published.in 1986, the Metropolitan Index of the Quality of Air (IMECA in Spanish) on a daily basis, in order to inform on the levels of pollution in the MCMA. This index shows the relation to a standard of 100 for pollutants in each one of five metropolitan zones (northeast, northwest, central, southeast, and southwest).

The Environmental Contingency Program has been applied on several occasions since 1987. This program foresees critical situations for all pollutants; it's actions are directed towards reducing the emission from sources of ozone, thus reducing these pollutant's concentration in the short term.

ACTIONS. As a result of the information gathered on the main causes and processes that affect atmospheric conditions, several actions have been implemented at sectorial and inter-institutional level in order to prevent and control the impairment of the quality of air. Among these actions are: the creation of a regulating framework for the Motor Vehicle Emission Verification Programs, and their establishment in the MCMA with a mandatory nature; the application of the no circulation ("Hoy no circula") program in the MCMA for the winter season 1989-1990; compulsory use of the most advanced and accessible technology for the control of vehicle emissions of new automobiles; the improvement of gasoline and it's combustion by adding oxygenated compounds like methyl-therbutylic ether (MTBE); total substitution of heavy fuels by natural gas in both thermoelectric centrals; the implementation of the Program for the Control of Vapor Emission in PEMEX Storage Tanks and Distribution Vehicles; completion of 118 agreements with the industry for the installation of control devices for nitrogen oxide emission.

 

Water Quality

In Mexico, like in many other countries, the main water pollution sources have been grouped inside three sectors, according to their origin:

— Social origin, which correspond to domestic discharges and constitute municipal wastewater.

— Agricultural, generated by the runoff from installations for breeding and fattening of large and small cattle, and residual waters from agricultural farmland.

— Industrial, generated by discharges from resource extraction and transformation activities (into consumable goods).

EXISTING TREATMENT SYSTEMS. There are presently 361 municipal wastewater treatment plants, with an installed capacity of 29.10 mVs; there are also approximately 282 industrial wastewater treatment plants, with an approximate installed capacity of 20 m-Vs. This shows that, from the total municipal wastewater discharge of 105 mVs, only 24% can be presently treated; besides, approximately half of the treated water is for reuse, and not for pollution control. As to industrial wastewaters, with a total discharge of 79 mVs, only 25.3% is treated.

 

Table 4
Air Quality Evaluation Criteria
Pollutant	Criteria (standard)
Carbon monoxide	13ppm in 8 hours
Sulfur dioxide	0.13 ppm in 24 hours
Nitrogen dioxide	0.21 ppm in 1 hour
Ozone	011 ppm in 1 hour
Particles (less than 10 microns)*	150 ug/m in 24 hours
Total suspended particles	275 ug/m3 in 24 hours
Lead	1.5 ug/m3 (3 month average)
Source: integral program against atmosphere pollution. Technical intergovernamental Secretariat, October, 1990 *International criteria

 

The existing municipal treatment plants mainly use processes based on stabilization containers and active mud, while the industrial treatments systems mostly use active mud processes with chemical coagulation.

HYDROLOGICAL BASINS. The hydrological basins where sanitation measures are being taken are: Lerma-Chapala, Balsas river, San Juan river, Blanco and Panuco river basins, as well as Patzcuaro lake and the border area. The need for keeping a continuous and systematic record of water quality in the main bodies of water of the country was determined as a result of specific studies, leading to the creation of the Water Quality Monitoring Network (which presently has 364 stations). With the help of this network, sampling and periodical analysis of superficial, underground and coastal waters has been carried out, including physical,chemical and bacteriological studies from strategic locations throughout the country.

In accordance with the National Environmental Protection Program for 1990-1994, laboratories for analysis are being continually equipped, and pollution sources are being constantly inventoried. The SEDESOL has been developing and implementing a series of techniques and methods to determine the degree of toxicity of water in the fastest and safest way possible,with the intention of evaluating the presence of toxic pollutants in superficial and residual waters, as well as for establishing the potential threat these represent to the users of the resources and to aquatic ecosystems in general.

LEGISLATION. The ecological criteria for water quality were published on December 13, 1989, in the Official Journal of the Federation. These include a total of 24 parameters and 98 substances that, due to their negative effects on human health or the ecosystems, have been considered of top importance. These criteria establish the minimum quality required for use and consumption of water, and the technical ecological standards which establish the prerequisites that must be observed to guarantee the population's well being, as well as assure the preservation and restoration of ecological balance and the protection of all the country's water sources. Between 1988 and 1989, a total of 33 technical standards for the control of industrial wastewater discharges into the sewage and agricultural runoff reuse were published.

 

EVALUATION AND CONTROL OF TOXIC SUBSTANCES.

In 1989, a National Program for the Control and Evaluation of Toxic Substances in Superficial Waters was established, with the main objective of determining the degree of pollution in our superficial waters due to these type of substances, as well as for implementing the necessary policies for the prevention and control of pollution due to toxic substances. In coordination with this program, studies are presently being conducted in the five main basins; these studies regard, among other aspects, both the degree oftoxicity of the waters, as well as their metal and pesticide content. In the same way, the program coordinates studies that focus on the adequate technologies for their elimination from wastewaters. In order to confirm the absence of toxics in both industrial discharges and bodies of water, the SEDESOL has been devising the appropriate technologies (biotests) that will permit the detection of these types of compounds in a fast and safe manner. A laboratory has been created for this purpose, where acute toxicity tests are carried out under the methodology proposed by the Pan-American Center of Sanitation Engineering and Environmental Science, and the Latin American Regional Project for the Control of Toxic Substances.

 

Municipal Solid Waste

Solid wastes are classified according to their source in: municipal, industrial, hazardous, or non-hazardous. In the first two cases they are categorized depending on the source of generation, and in the third case, division is made according to the handling, treatment, and disposal requirements of this particular type of waste.

According to the last population census (National Statistical, Geographical and Informative Institute -INEGI-, 1990), the country has a population of 82 763 740 inhabitants, which generate 59 085 tons of solid waste a day, with a total of 21 566 025 tons generated every year.

The efficiency of the disposal systems is moderate,with an estimated 41 359 tons/day collected, (70% of the total), adding up to 15 096 035 tons a year. Of these, 12 407 tons/day are deposited in landfills -30% of the collected waste- or 4 528 810 tons a year; the remaining 28 952 tons collected daily are disposed of in open dumps and reach a total of 10 567 480 tons a year.

As to standard setting, 17 official standards regarding solid waste disposal have been published in our country. Integral management of municipal solid waste disposal faces a difficult situation due to the need for establishing a self-supporting tax system, so that waste management may be efficient, punctual, and organized.

 

Hazardous Wastes

According to international terminology, Mexico has adopted the so called CRETI code for the categorization of hazardous wastes (corrosive, reactive, explosive, toxic and ignitable), besides the infectious wastes, generated in hospitals, clinical analysis labs, as well as research and higher education centers.

GENERATION. Industrial wastes generated nationwide amount to approximately 450,000 tons a day, of which 337,500 correspond to extractive mining and melting of non-ferrous metals; 81,000 tons correspond to processes from basic chemical, organic and inorganic, industries; 31,500 are due to agro-industrial wastes,among which the more important ones are the sugarcane industry, the coffee industry, and the juice and oil concentrating industries. All of the above generate a total of 164,250,000 tons a year of industrial waste. Of this figure, 14,500 tons a day (the equivalent of 5,292,500 tons a year), are wastes considered to be hazardous, which a primarily generated in the chemical industry -both organic and inorganic-, as well as in the petrochemical industry. Heavy metals are produced by the smelting of ore, in the concentration of certain non-ferrous metals (like precious metals), and in the production of agrochemicals. Mexico City generates approximately 173,520 tons a month of industrial waste.

FINAL DISPOSAL OF HAZARDOUS WASTE. Mishandling of hazardous wastes, like their unauthorized disposal in abandoned dump yards or sites, in river beds, estuaries, or in the sea, causes substantial damage to the environment and it's resources and, given the persistence of many of these pollutants, they can enter the human food chain, gravely affecting human quality of life.

The strategy adopted by SEDESOL for the control of toxic and hazardous substances establishes, in it's first stage, the need for reducing their generation by recycling, their physical, chemical and biological treatment, as well as their incineration and controlled impoundment. Through concertation, the institution has convinced several private industries of installing plants for the treatment and disposal of the wastes they generate. Another fundamental measure of control in the future will be the exclusive authorization of new plants with clean technology within their processes, in order to reduce waste generation.

 

Health and Safety

ENVIRONMENTAL HEALTH. Human health is directly linked to environmental quality and conditions and, particularly, with the distribution of drinkable water,water management, the disposal of human and municipal wastes, the presence of noxious organisms, and physical, chemical and biological pollution. All this is reflected in each society's health and death patterns.

Mexico presents an epidemic transmission phenomenon, where several transmissible diseases coexist, among them acute respiratory diseases and diarrhea, as well as those associated with modem urban and industrial life, like cancer; this emphasizes the need for facing both basic sanitation problems, as well as those derived from other activities that generate different factors that jeopardize human health. The above implies that traditional sanitation schemes must be expanded to evaluate a wider range of environmental effects on health, studying the adverse effect of physical and chemical pollutants on the population, an area that is still incipient in our country.

DRINKING WATER AND SANITATION. Dysenteric diseases are among the most frequent causes of illness and death in Mexico. The crucial lack of water in most of the territory has made it necessary to employ wastewater for irrigation, which has had a positive fertilizing effect in arid soils. However, such use poses a threat to human health, specially when used on vegetables, which are eaten raw, due to the presence of pathogen organisms like viruses, bacteria, protozoons, and helmith worms which are the cause of diseases considered a public health in Mexico. In addition to this risk, there is the hazard of human exposure to persistent materials that are subject to accumulation, like heavy metals; this risk is accounted for by industrial effluents that carry potentially toxic chemical compounds, which flow to water reserves used for irrigation. Consequently, the Secretariat of Health (SSA) has issued sanitation criteria where the Technical Ecological Standard is supported, prohibiting the use of wastewater for the irrigation of crops that grow at ground level and that are eaten raw.

The importance water-related and basic sanitation problems have for the Mexican government is patent in the National Strategy for the Observance of Water Pollution Problems, and in the Clean Water Program, upheld by president Carlos Salinas de Gortari, who has pointed out that to act against pollution problems is to forestall health problems, for it would be illogical to channel extraordinary investments for hospitals and health care for the Mexican people if efforts were not also made to counter the origin of these health problems.

ATMOSPHERIC POLLUTION. Knowledge of the effects of atmospheric pollution on the population is a fundamental element in the definition of maximum permissible limits of pollutants in the atmosphere, as well as for optimizing actions that involve an intersectorial emergency response. The SSA is therefore carrying out studies and collating information to evaluate such effects on the inhabitants of urban areas like the MCMA.

There are studies on: evaluation of the effects, and control of exposure to lead; arsenic and fluoride pollution; health risks due to exposure to hazardous wastes; danger of intoxication from pesticides; prevention and control of toxic related accidents; environmental health problems in the northern border,and; the importance of personal health care in the prevention of environmental hazards, among others.

Three fundamental elements have been emphasized for the safekeeping of human health against negative effects from environmental pollution: implementation of an adequate regulative framework; the development of control measures, and; public education.

 

Noise

Noise is a characteristic pollutant of large urban centers. It can cause disorders and diverse disturbances like stress, and may even cause physiological damage.The main sources of noise pollution are industrial and commercial activities, besides air and land transportation.

In order to reduce this type of pollution, different levels of government have included various actions in their programs. For example, different cities in the country have carried out noise reduction programs, consisting of obligatory engine changes to motor vehicles and control of exhaust systems, specially in diesel engines.

 

Environmental Impact and Risk

Evaluation of environmental impact is one of the most efficient means available to the State for the implementation of ecological policy and environmental planning for the country's development. It's importance is directly related to the damage that may be prevented to the direct ecological vicinity of it's action. The evaluation of a project or activity subject to an environmental impact study considers the magnitude and nature of possible environmental effects generated by it's own construction or activity. Roughly, the following aspects are taken into account: characteristics of the projected work or activity; chosen location for it's development; required input; general socioeconomic and natural environment conditions; relation with standards and regulations for land use; recognition of environmental impacts; prevention and mitigation measures to be implemented, and; the environmental scenario after the conclusion of the work or activity.

The declaration of environmental impact must be made before SEDESOL by those responsible of all public or private works that lie within the legislative framework of the General Law of Ecological Balance and Environmental Protection, in effect as of march 1, 1988. The agendas of different productive sectors, like tourism, energy, transport and fishing have been looked into.

 

Environmental Emergencies and Contingencies

In broad terms, to talk about environmental emergencies and contingencies is to talk about technical criteria of classification, as well as measurement, prevention and control of incidents of water, air, land, and natural resource pollution, alongside their effects on human health.

ENVIRONMENTAL EMERGENCY AND CONTINGENCY PROGRAMS. Among the most important environmental emergency and contingency plans and programs in the country are: Joint Response Program for Hazardous Waste Spills in the Border Area (within the Mexico-USA treaty); National Contingency Plan for the Control and Containment of Hydrocarbons and other Noxious Substances in the Sea; Bilateral Agreement on Pollution of the Marine Environment by Hydrocarbon Spills and other Harmful Substances (Mexico-USA); Plan for the Tacana Volcano; External Radiological Emergency Plan; International Agreement for the Prevention of Hydrocarbon Sea Water Pollution; London Agreement on Prevention of Pollution of the Sea form Waste Spills and other Substances; Agreement for the Protection and Development of the Marine Environment of the Greater Caribbean Region; the Contingency and Emergency Programs for Atmospheric Pollution Incidents in the MCMA.

CONTINGENCY PROGRAM FOR ATMOSPHERIC POLLUTION INCIDENTS IN THE MCMA. Agreed by all the involved sectors and within the framework of the National Civil Protection System,this program consists of the adoption of sectorial measures to decrease dangerous levels of pollution and, simultaneously, spread adequate and prompt information to the public as part of an emergency situation. The participating sectors are: government, private, social and the general public.

The Program considers, by means of the actions it establishes, the reduction of industrial and motor vehicle atmospheric emissions, which lead, with the objective of protecting the population, to a virtual interruption or suspension of activities. The Program may be enacted during any season of the year.

Measures have been divided into three phases,depending on the seriousness of the situation:

Phase I.If the level of pollution fluctuates around 250 points IMECA in large areas of the city, and atmospheric forecasts are unfavorable.

Phase II.Becomes active when pollution reaches 350 points IMECA, depending once again on how generalized the problem is and an meteorological forecasts.

Phase III. It would be enacted in the case of a critical situation, with over 450 points IMECA and an adverse atmospheric forecast. In this phase, there would be an additional suspension of activities, similar to a national holiday.

EMERGENCY PROGRAM FOR ATMOSPHERIC POLLUTION INCIDENTS IN THE MCMA. It will be applied in the unlikely, although not impossible event of a failure of the contingency program to produce satisfactory results in the reduction of pollutant concentration within a specific area of the city. Linked to the contingency program, it is designed to radically and immediately confront any serious pollution problem in the Metropolitan Area of Mexico City.