Sources of Household Air Pollution & its Health Effects, Strategies to Deal With it, Risks

Around 3 billion people in the world use the traditional methods of cooking, i.e., burning solid fuels (wood, crop wastes, charcoal, coal, and dung) and kerosene in open fires and inefficient stoves, out of which 3.8 million people a year die prematurely. The majority of such populations are from poor, low, and middle-income countries such as South East Asia. The inefficient use of fuels and technologies in cooking practices have produced high levels of household air pollution. It has resulted in the formation of health-damaging pollutants majorly small soot particles that can penetrate deep into the lungs.

This indoor smoke is 100 times higher than the acceptable levels of fine particles. Exposure is found maximum in women and young children who spend the most time in the home. Other than cooking fuel, there are more than sixty sources of household air pollution varying from country to country. Indoor tobacco smoking, construction material used in buildings, use of incense sticks, mosquito repellents, pesticides, and chemicals for home cleaning, artificial fragrances are some of the top list household air pollutants.^[1][4]

Household air pollution is defined as the third leading cause of disability-adjusted life years globally. Life is affected at all stages from preconception to old age due to this indoor pollution. Exposure at any age can resonate for an entire lifetime. The respiratory system bears the maximum brunt, but effects on the heart, endocrine system, and nervous system cannot be forbidden. Therefore, the foremost challenge in preparing someone to battle against household air pollution is to provide the complete knowledge of household air pollutants and their health implications.^[2][3]

The purpose of this article is to get a thorough knowledge of various sources of household pollutants, its effect on health, and strategies to deal with the risk associated with household pollution. Further, the impact of indoor pollution on development and WHO response towards mitigating the risk of household pollution has been discussed.

Cooking: Fuels used in cooking such as biomass (wood, crop residue, animal dung cakes, and wood charcoal) are the major pollutants in rural households. China alone is responsible for 420,000 deaths annually due to the indoor pollution caused by the use of solid fuels. In developed and developing countries, the use of electricity, natural gas, or clean LPG is responsible for household air pollution.

Smoking: Smoking tobacco within the premises of the house is considered another primary source of household air pollution. Cigarettes contain around 7,357 chemical compounds, benzene, CO, PAHs, heterocyclic amines, cyanide, formaldehyde, terpenoids, phenols, nicotine, and heavy metals top the list. The effect of these harmful chemicals is not limited to the smoking person only. Tobacco smoke is classified as

• First-hand smoke: a person who is smoking is exposed to the smoke
• Second-hand smoke: other occupants of the house who are inhaling these fumes but not smoking themselves
• Third-hand smoke: particles emitted during smoking get settled on the hairs, clothes, floor, and ceilings. These suspended particles remain for a long time in the air even after the exit of the primary smoker.

Temperature Control: Air conditioners used in households for temperature and humidity control are the reason for the accumulation of particulate matter pollutants inside the premises. Preventing the temperature-controlled air from escaping the closed environment further complicates the situation. Also, inadequately cleaned air conditioning units can quickly become the breeding grounds for several fungi and bacteria.

Insecticides and Pesticides: Two billion people across the globe use mosquito coils to battle against the dangerous and widely spread mosquito-borne diseases such as malaria and dengue. The standard composition of a mosquito coil is 0.1% of the active repellent pyrethroids; rest 99.9% contains binders, resins, and flammable material such as coal dust and coconut husks. Burning off one mosquito coil emits particulate matter equivalent to the burning of 100 cigarettes; hence, use of coils can also be a primary cause of household air pollution.

Perfumes, Deodorants, and Cleaning Agents: The air fresheners, laundry items, personal care products, and cleaning agents used in the houses contain around 150 different volatile organic compounds out of which 42 have been already stated as toxic by the US Food and Drug Administration. PAHs, benzene, nitrous oxide, and CO tops the list when fragrances such as incense sticks are burnt.

Construction Material: Paints and varnishes, particulate board furniture, and insulation material used in buildings have been implicated in emitting volatile organic compounds, hence, increasing the burden of household air pollutants.

Excess Moisture: Moisture is often one of the least recognized but important household air pollutants. The problem arises when warm moist air from outside enters the house strikes on cooler surfaces such as mirrors, windows, or walls. Cooler air can hold less moisture, so the excess water gets condensate in the form of droplets on the surface. The collected moisture on the surfaces invites the mould, mildew, and dust mites, leading to several kinds of allergies or asthma.

Radon: It is a radioactive gas generated naturally in the soil, hence, enters the house from the ground. Radon is considered the second leading cause of lung cancer in the US.^[1]

Pneumonia: Exposure to household air pollution doubles the risk for childhood pneumonia. 45% of deaths due to pneumonia in children less than five years old are found to be due to indoor pollution only. It is also the risk for acute lower respiratory infections (pneumonia) in adults and contributes a reason to 28% deaths in them.

Chronic Obstructive Pulmonary Disorder: Household air pollution contributes towards 25% of death in adults in low- and middle- income countries due to chronic obstructive pulmonary disorder (COPD). Indoor smoke is more damaging than cleaning agents or other household pollutants COPD patients.

Stroke: Household air pollution from cooking using solid fuels and kerosene contributes to 12% of deaths due to stroke.

Ischemic Heart Disease: Exposure to household air pollution can be accounted for in terms of millions of premature deaths annually, out of which 11% are from ischemic heart disease only.

Lung Cancer: The exposure to carcinogens from household air pollution (emitted from cooking with kerosene or solid fuels) can account for 17% of deaths in adults due to lung cancer.

Other Health Impacts: The particulate matter released from the smoke can easily find their entry in airways and lungs which can impair the immune responses of the body or reduce the oxygen-carrying capacity of the blood. The evidence of strong links between household air pollution and low birth weight, tuberculosis, cataract, nasopharyngeal, and laryngeal cancers have also been established.^[2][3][4]

The three fundamental strategies that can be adopted to improve indoor air quality are:

• Source control
• Improved ventilation
• Air cleaners

The solution to every problem is to remove the cause. Similarly, eliminating the sources responsible for household air pollution or reducing their emissions is considered the most effective way to improve indoor air quality. For example, asbestos can be sealed or enclosed; or gas stoves can be adjusted to minimize the emission. Source control is also a cost-effective strategy, as increasing ventilation will also increase your pocket costs.

Another optimum strategy to reduce the concentration of household air pollutants is to increase the amount of outdoor air entering the premises. It can be done through the following ways:

• Use of windows and doors, i.e., natural ventilation
• Mechanical means such as air conditioning
• Infiltration, a process in which outdoor air can flow inside the house through openings, joints, and cracks in the walls, floors, and ceilings, or windows and doors

The effectiveness of an air conditioner is decided by its percentage efficiency rate, i.e., how efficiently it collects indoor air pollutants. Also, how much air it can draw through the cleaning or filtering element (expressed in cubic feet per minute) decides the efficiency of your chosen air conditioner.^[6]

According to the 2017 report of the International Energy Agency, without the noticeable changes in the current policies concerning the control of household air pollution, the total number of people who are lacking access to clean fuel and technologies will remain largely unchanged by 2030. Hence, hindering the achievement of 2030 Agenda for Sustainable Development.^[5]

WHO plays a crucial role in providing technical support to countries for evaluations and scale-up of health-promoting household fuels and technologies at regional levels. The Clean Household Energy Solutions Toolkit (CHEST), a set of resources that help countries in identifying stakeholders working on public health or household energy, is currently supporting the implementation of WHO Guidelines for indoor air quality Household fuel combustion. These guidelines provide the following health-based recommendations:

• Types of fuels and technologies to be used to protect health and reduce household air pollution
• Build strategies for effective dissemination and adoption of optimum household energy technologies.^[6]

Despite the deep understanding of household air pollution, there is still room for further research on newer sources of indoor pollution. Based on current knowledge, the long-term measures taken to curb the health effects associated with household air pollution have remained grossly insufficient. However, the support of CHEST in the implementation of WHO guidelines on indoor air quality and integrated support from the healthcare profession, industry, and healthcare policymakers can produce better effects in controlling household air pollution and its impact on health in the future.

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