The most important law in Malaysia which directly relates to environmental pollution is the Environmental Quality Act (EQA) 1974 (amended 1985). With the passing of this Act, a Division of Environment now upgraded into the Department of Environment (DOE), under the Ministry of Science, Technology and Environment was established. The Act gives the mandate and the means to the Director-General of the Department of Environment to achieve national goals in environmental protection

In order to manage the air quality in Malaysia effort has been made to identify the various sources that can contribute to air pollution and in particular the severe haze episodes. The severe haze episodes that had occurred regularly since the early 1990's have increased awareness of air pollution and need for pollution control in Malaysia. The first concerted attempt to determine the air pollution status in Malaysia was undertaken under a technical cooperation with the government of Japan under the Japan International Cooperation Agency (JICA) under a program entitled "Air Quality Management Study for Klang Valley Region". An estimate of the air pollution load from various sources in the Klang Valley region for 1992 was done by the JICA study. From this estimate it can been seen that about 85% of SOx emission came from burning of heavy duty oil or coal in power stations and general factory boilers. In the case of NOx, CO, and HC, the main source of emission is from motor vehicles.

The impact of pesticides on human health arises from occupational exposure and ingestion of tainted foodstuff. Because of the toxic nature of pesticides, legislations are in place to safeguard human health and the environment from pesticide residues. In this regard, government agencies such as the Department of Agriculture, Department of Environment and Department of Health have been given the task to administer and enforce regulatory policies and laws pertaining to all aspects of pesticide use, such as the Pesticide Act, the Environmental Quality Act and the Food Act/Regulations. The impact of pesticides on the paddy-field ecosystem has been assessed primarily on acute laboratory toxicity tests conducted on fish commonly-found in the paddy-fields. In addition to toxic effects, many of the chemicals also result in bioaccumulation in biota, giving rise to transport of the chemical through the food chain. Severe phytotoxicity has also been observed as a result of improper herbicide usage and application and continuous adoption of a single weed control method resulting in serious weed-shifts. As a means to promote more judicious use of pesticides in the paddy-fields integrated pest management (IPM) strategies involving a variety of biological, physical and chemical methods have been adopted with varying degrees of success.

Industrial development has contributed significantly to the problems of pollution by toxic and hazardous waste which may in some ways pollute surface waters in rivers and lakes if not disposed properly. These wastes which include acids, asbestos and heavy metal sludge are outputs of the metal finishing industries, textile industries, gas processing, foundry and metal-works and asbestos factories. The specific problems related to drinking water in Malaysia are numerous. In most states of the Peninsular Malaysia, Sarawak and Sabah surface waters are the main sources of drinking water, i.e. from rivers and reservoirs. These rivers are administered by the state governments. The rapid development of industries has contributed considerable pollution to the rivers of the countries. Surface water pollution by organic matter is one of the major problems in most areas of the country. Organic matter sources include industrial discharge (agrobased and non-agrobased), domestic discharge, domestic sewage (partially treated and untreated) and animal waste (mainly from pig rearing). Suspended solids, largely from development activities (housing and urban), deforestation due to logging, is another significant contributor to surface water pollution. Water pollution is particularly serious in areas of high population density and where these are significant numbers of agrobased and other industries. The major organic chemicals used in large scale are the herbicides and pesticides. Other toxic chemicals such as phenolics and polychlorinated biphenyls (PCB) are also of concern.

The concern for the possible environmental effects of complex industrial and municipal discharges requires that more subtle techniques and potentially long-term effects have to be taken into account to an increasing degree in regulatory work. The testing for water quality is carried out by several government department and ministries. These are the DOE, DID, PWD and MOH. In addition, various other institutions both private and governmental also undertake monitoring but on a limited scale and for specific purposes mainly relating to particular project activities. The National Electricity Board, undertakes rainfall, river discharge and sediment monitoring, mainly in areas where hydroelectric power generation projects are undertaken. The Geological Survey Department conducts various studies to evaluate groundwater potential in various parts of the country. The Department of Environment currently operates 350 water-quality monitoring stations in the 49 water quality control regions throughout Peninsular Malaysia.