Indoor Air Pollution (IAP)

Overview

Indoor air pollution (IAP) also called household air pollution (HAP) in developing countries is a major environmental and public health challenge. According to data from the World Health organisation as many as 4.3 million people died in 2012 as a result of it worldwide. This can be compared with one death every 8 seconds. Most of the death occur in middle and low income countries in South East Asia with 1.69 million death, followed by the Western Pacific regions 1.62 million, Africa 600,000, Eastern Mediterranean region 200,000, Europe 99,000, and in the Americas 81,000 death. In high income countries 19,000 people died because of IAP. IAP/HAP has to be distinguished from outdoor ambient air pollution (AAP) which supposedly caused the death of another 3.7 million people in 2012.
Indoor sources of IAP/HAP are cooking and heating with solid fuels, burning candles or oil lamps, fuel-burning space heaters and tobacco smoke. Of special importance is inefficient and insufficiently vented cooking and heating with solid fuels (biomass and coal) on simple stoves or open fires. Burning these fuels in inefficient stoves results in poor combustion efficiency and high levels of emissions of health-damaging pollutants including both fine and coarse particulate matter, carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), and a variety of organic air pollutants (e.g., formaldehyde, 1,3-butadiene, benzene, acetaldehyde, acrolein, phenols, pyrene, benzopyrene, benzo(a)pyrene, dibenzopyrenes, dibenzocarbazoles, and cresols). In a typical solid fuel stove, about 6–20% of the solid fuel is converted into toxic emissions (by mass). The exact quantity and relative composition of the emissions is determined by various factors such as the fuel type and moisture content, stove type and the way the stove and fuel is used by the cook. Most measurements of emissions and the corresponding literature focus on the concentration of particulate matter of different sizes (e.g., PM_2.5, PM₁₀) and carbon monoxide (CO), which are main products of incomplete combustion and are considered to pose the greatest health risk. According to estimations 2.9 billion people used solid fuels (mainly biomass, in the form of wood, charcol, dung, and crop residue) for cooking and other heating purposes in 2012 . Around 80% of them reside in rural and 20% in urban areas. Because much of the burning of solid fuels is carried out indoors in environments with insufficient ventilation, millions of people, primarily poor women and children face serious health risks.

Health Effects

According to WHO there is consistent evidence that exposure to household air pollution is a major risk factor leading to acute lower respiratory infections (ALRI) in children under five, and ischaemic heart disease (IHD), stroke, chronic obstructive pulmonary disease (COPD) and lung cancer (LC) in adults.In addition, the smoke from burning biomass is also causing eye irritations.
Smoke in form of particulate matter with particle diameters of less than 10 micrometers in diameter penetrate deep into the lungs. At sizes of 2.5 micrometers particles can enter the finest parts of the lungs. Ultrafine particles get even into the bloodstream. Exposure to particulate matter has short-term effects such as nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath as well as more severe effects on the respiratory system such as pneumonia and asthma. Children are especially affected by ALRI. A child exposed to smoke in the home is two to three times more likely to catch pneumonia. Globally, pneumonia and other acute lower respiratory infections represent the single most important cause of death in children under five years. Exposure to IAP more than doubles the risk of pneumonia. Women exposed to indoor smoke are three times as likely to suffer from chronic bronchitis and other obstructive pulmonary diseases (COPD) than women who cook and heat with electricity, gas and other cleaner fuels. In addition, there are indications, that indoor smoke is also causing tuberculosis, cataracts, low birth weight and high infant mortality. Most of the victims of IAP are women and children, as they are exposed to the source of indoor smoke and the large associated health risks the most. Women spend daily three to seven hours near the stove with their kids breathing polluted air during cooking. At the early age of the children, when they are newborns or infants, their immature lungs and immune systems make them particularly vulnerable. Over 10 million children aged under five years die every year – 99% of them in developing countries. According to Global Disease Study 2010 the relationship between exposure to pollutants and health effects is often not linear. In the case of PM_2.5 an exposure response model estimating health effects by using relative risk (RR) information for ALRI, IHD,stroke, COPD, and LC is assuming a kind of exponential saturation curve. The health risks rise significantly with increasing concentrations of PM_2.5at lower levels. The effect becomes less pronounced at higher PM_2.5 exposure levels. This has major implications for strategies to reduce health risks by controlling air pollution at high exposure concentration levels.

Regulations and Recommended Maximum Concentrations of PM and CO

Due to the severe health risks of air pollutants, many governments and international organisations have defined maximum concentrations of pollutants for emissions allowed from certain types of pollution sources, for the ambient air (immissions) and for workplaces or short periods of exposure. This chapter only presents the data for PM and CO as they are most widely used to measure the degree of air pollution.
The following table gives an overview about current standards.

Pollutant	Standard	Averaging Time	Country/Region
PM10	150 μg/m³	24-hour	USA
	50 μg/m³	24-hour	EU
	40 μg/m³	annual	EU
	150 μg/m³	24 hrs	China
	70 μg/m³	annual	China
	50 μg/m³	24 hrs	WHO
	20 μg/m³	annual	WHO
PM2.5	35 μg/m³	24-hour	USA
	15 μg/m³c	annual	USA
	25 μg/m³c	annual	EU
	75 μg/m³c	24 hours	China
	35 μg/m³c	annual	China
	25 μg/m³c	24 hrs	WHO
	10 μg/m³c	annual	WHO
CO	35 ppm (40 mg/m³)	1-hour	USA
	9 ppm (10 mg/m³)	8-hour	USA
	9 ppm (10 mg/m³)	1-hour	EU
	10-20 mg/m³	1-hour	China
	35 mg/m³	1-hour	WHO
	10 mg/m³	8-hours	WHO

The table shows a certain variability of the air quality standards in different countries and regions. The variability is mainly caused by different short and long term air quality targets of the countries, the path to obtain these targets considering resources, location, economic structure etc..
In the case of PM2.5 WHO has defined three interim air quality targets for annual outdoor PM2.5., taking into consideration that achieving the full target will not be realistic for most developing countries in a short period of time. The interim air quality targets are: Level 1: 35, level 2: 25, and level 3: 15 μg/m3 per year.

IAP/HAP and Cooking Systems

According to estimates more than 2 billion people use solid fuels (wood, dung, crop wastes, charcoal, coal, etc.) and simple stoves with incomplete combustion of the fuel for cooking and heating. Hundreds of million households light their homes with kerosene and simple wick lamps. Both practices produce high levels of pollutant emissions and as a general result considerable indoor/household air pollution. However, high emissions do not necessarily lead to high air pollution (immissions) or high exposure levels. Pollutants emitted into the air diffuse throughout the surrounding space or are transported to other air spaces and diluted. This can happen inside the kitchen, between kitchen and living rooms and to the outside air. The resulting immssions are a mixture of ambient air pollution and the household air pollution.The exposure level again depends on the activity pattern, length and frequency of a person being exposed to the immissions in specific rooms or areas.

The typical 24-hour levels of PM10 in biomass-using homes in Africa, Asia or Latin America range from 300 to 3,000ig/m3. Peaks during cooking may be as high as 10,000ig/m³ especially during the beginning ignition process when combustion is especially incomplete.

Remote rural areas are likely to have better ambient air quality (even when biomass use is higher) than urban or periurban or well-connected rural locations where a more intensive use of commercial fuels and the higher traffic affect stronger the ambient air quality.

Reducing Indoor Air Pollution (IAP)

Measures to reduce IAP in developing countries:

• Changes in energy technology, switching to cleaner alternatives (kerosene, liquid petroleum gas, biogas, electricity or solar energy)
• Improving the design and construction of traditional stoves (improved stoves or smoke hoods that vent pollutants to the outside
• Behavioral changes using a pot lid when cooking to speeds up the cooking, drying wood before burning it, awareness-raising activities)
• Change the living environment (kitchen ventilation)

Cleaner Fuels / Improved Cookstoves

The most effective way to reduce smoke in the home is to switch to cleaner fuels (liquid petroleum gas, kerosene or biogas). It’s also possible to improve the air quality and promote energy efficiency and environmental sustainability by promoting improved cooking stoves.

Smoke Hoods

The huge majority of people in developing countries who are still cooking on open fires are often too poor to change to improved stoves and cleaner fuels or have no access to modern combustibles. Where the use of biomass, wood or charcoal remains predominant, and the indoor environment remains subject to high levels of smoke, other alternatives have to be found to improve air quality and related health issues. The installation of a smoke hood can be extremely effective in improving the air quality in houses. This applies especially, when traditional biomass burning stoves are being used without a chimney. In addition, some efficient stoves may not be clean and therefore employing a smoke hood allows for health benefits coupled with lower operating costs. Moreover, in some cultures, an open fire plays a special social role as a place around which the family gathers, traditional meals are cooked or other important rituals. As a result the introduction of improved cookstoves is difficult and a smoke hood serves as the best alternative for improving indoor air quality.

Impacts

Reaching this goal to reduce this extremely harmful IAP would significantly help to achieve several of the internationally agreed Millennium Development Goals, especially Goal 4. Reduce child mortality with the target to decrease by two thirds, between 1990 and 2015, the under-five mortality rate. Since 1990, the mortality rate for children under age five in developing countries dropped by 28% (from 100 deaths per 1,000 live births to 72 in 2008), but not quickly enough to reach the target by 2015. Many organizations are already working on this field to make improvements in this issue.

Further Information

• Smoke Hoods - "Healthy Hoods" Project
• Indoor air pollution in developing countries: a major environmental and public health challenge
• Indoor air pollution (IAP) Measurements
• Health Hoods, Smoke Hoods for developing countries Video (Project by Practical Action and BSH)
• HEDON Hompepage with Video - THese Women's stories tell the cookstoves story
• Hyley in Nepal (The silent killer in Nepal) (Video by Practical Action)