 As you've learned about environmental inequality in the context of air pollution and understood air pollution issues through intersectionality lens, you saw that different groups of people have been disproportionately affected by air pollution, depending on who they are, where they live, and what they work. This module will delve into occupational exposure with an overview of the impact of air pollution on workers' health, with a specific focus on Southeast Asia. Air pollution can simply be defined as harmful substances which alters the natural characteristics of the atmosphere. The two most harmful air pollutants in terms of health impacts are particulate matters or PM2.5 and tropospheric go-zone. PM2.5 refers to particulate matter with a diameter less than 2.5 micron. It is particularly harmful due to its ability to enter into the bloodstream and travel to any area of the body, causing irritation and inflammation. PM2.5 can be emitted directly from sources such as burning of biomass, but it can also form in the atmosphere from pollutant gases. There are many different sources of air pollution, and the key source sectors experience spatiotemporal variation. Key source sectors for PM2.5 emissions are often road transport, residential cooking, fossil fuel consumption in industry, open waste burning, and agricultural crop residue burning. Understanding the key sources of air pollution can help to inform policies which aim at mitigating air pollution. This photo compares the size of PM2.5 with dust, human hair, and fine beach sand. Exposure to air pollution has been associated with various health impacts, including increased risk of cardiovascular disease, respiratory infections, lung cancer, stroke, and diabetes. According to the World Health Organization, or WHO, an estimated 6.9 million premature deaths or over 10 percent of worldwide deaths were due to air pollution in 2016, 70 percent of which were in the Asia-Pacific region. The WHO recommended guidelines states that the average person's annual exposure to PM2.5 should not exceed 5 micrograms per cubic meter. However, concentrations in most countries, particularly low and middle income countries, is much higher than this. There are three different ways in which people can be exposed to air pollution, and some people might be exposed to all sources of air pollution. The first type of exposure is ambient exposure, which refers to the exposure that people face due to air pollution in the outside air. Everyone is exposed to ambient air pollution. However, there are spatiotemporal variations in ambient air pollution concentrations within regions, countries, or cities. People will be exposed to different levels of ambient air pollution depending on their locations. For example, ambient air pollution is often higher in urban areas, where key sources such as road traffic can significantly increase emissions. According to the Global Burn of Disease, or GBD study, exposure to ambient air pollution was estimated to result in 4.14 million numbers of premature deaths in 2019. The second one is household air pollution exposure. The key source of household air pollution is cooking with traditional biomass stoves, which is still extremely common in lower income countries, especially in rural areas. Traditional stoves emit high levels of harmful PM2.5 and leads to a high exposure to those who are cooking or who spend a lot of their time in the house. The health burden from household air pollution exposure is estimated at 2.31 premature deaths in 2019. A large proportion of the health burden from household air pollution is showered by women and children. As these are the people who typically spend most of their time indoors, people are often exposed to household air pollution in addition to their exposure to ambient air pollution, making this an additional source of air pollution exposure for many workers. The final way in which people can be exposed to air pollution is through their work. This is known as occupational exposure, which is the focus of this module. Occupational exposure describes the exposure of people to harmful air pollutants and other toxic substances due to their work, and can cover both formal and informal occupations, such as domestic care duties. This infographic shows examples of occupational exposure to air pollution. You see that different occupations potentially expose to air pollution and toxic substances at different levels based on where and what they work, and whether they have enough personal protective equipment. Exposure to air pollution can be highly detrimental to workers' health. The GBD estimates the increased risk of premature mortality due to cardiovascular disease through occupational exposure to PM, gases, and fumes, and the increased risk of developing cancer from exposure to occupational carcinogens. Globally, occupational exposure to PM, gases, and fumes was estimated to result in 524,000 premature deaths in 2019. However, due to lack of data on this source, it is likely that this will be an underestimate. The figure presented here shows the rate of deaths across the globe due to occupational exposure to PM, gases, and fumes. In Southeast Asia, occupational exposure to PM, gases, and fumes was estimated to be 32,500 in 2019, while occupational carcinogens contributed 350,000 deaths. Focusing on a few countries in Southeast Asia, we can look at the comparative health impacts of different types of air pollution exposure. Household air pollution causes the most deaths in Myanmar, Cambodia, Laos, and the Philippines. Occupational exposure has, in comparison, quite a small impact on total number of deaths but still has a high health burden. It is also likely that there is an underestimate of the health burden of occupational exposure to air pollution. The GBD study only quantifies the increased risk of cardiovascular disease due to exposure from this source, whereas for exposure to ambient and household air pollution, there is an increased risk of stroke, diabetes, respiratory infection, and lung cancer. The methodology and data requirements for estimating the health impacts of air pollution exposure are detailed in the following section. The first step is to determine the number of people working in each sector. We, firstly, establish the proportion of the population who are engaged in different occupations and then multiply this by the number of people who are working. This can be described as an economically active population. Data on economic activities can be found in the International Labor Organization or ILO database, which distinguishes 17 economic activities as you see in a diagram. The second step is to understand the level of pollution to which a worker is exposed to because of their occupation. This can be termed the exposure rate and is different for different economic activities. Exposure rate can be obtained from experimental studies, literature, or the GBD. Experimental studies and literature present measured data from occupational exposure, while the GBD categorizes exposure as either high, low, or none. Next, the exposure rate and the population exposed are then used to estimate the number of premature deaths. Each level of exposure has an associated risk for each relevant disease. This relative risk multiplied by the population that is exposed and the baseline mortality rate for each population group to estimate the number of premature deaths in each demographic group such as age and sex due to occupational exposure to air pollution. Overall, the key data required for estimating the health impacts of occupational exposure to air pollution include, 1. Estimated exposure for each population group and occupation of interest, 2. Increased risk or risk ratio for each disease and population group associated with increased exposure, 3. and mortality rate of the population group of interest. There are often barriers to conducting health impact assessment. The main challenge is data availability. Often data that is available is concentrated in certain regions and many countries in Southeast Asia are data scars. Moreover, even when data is available, it often does not include informal sectors. For this reason, estimates of health impacts from occupational exposure for informal workers are not included. Informal sectors are industries or occupations which are not officially registered by national governments and are typically not taxed or regulated. As a result, they are often difficult to collect data on and at the same time there are few policies in place to protect these workers. There are also practical barriers to data collection. For example, air quality monitors can be costly and require continuous measurements to be recorded. Many countries in Southeast Asia do not always have the capacity for this kind of undertaking. Lastly, the health impacts of exposure are often limited and can be focused in more developed countries such as Western Europe and the United States. Often health impacts of exposure are different for different population groups. Furthermore, there are a limited number of diseases considered when assessing occupational exposure. Consequently, more research is needed on associated health impacts from occupational exposure for more countries, demographic groups, and occupations. There are several ways that researchers, together with civil society groups and other sectors, can help reduce occupational exposure. First of all, more quantitative studies should be conducted to help estimate total air pollutant emissions from different types of work. The exposure in each occupation group will lead to improved estimates of health burdens and better informed policy. In addition, workers should be empowered to take action. Apart from quantitative studies, we need more qualitative studies to help us understand the different perceptions of air pollution from each occupation group and what policies are in place to understand key issues facing workers. Secondly, exposure in informal workers and the impact of exposure must be studied to better the estimation of exposure in different types of informal work. Thirdly, there are actions which can be taken to reduce occupational exposure of air pollution. Mitigation measures can be implemented to reduce emissions and exposure. For example, using greener and cleaner cooking fuels such as LPG. Another example is to use personal protective equipment or PPE such as masks or face shields which reduce the amount of pollutant a worker inhales. Improved ventilation or dust extraction can also help to diffuse air pollution and reduce concentrations around workers. It is also important to monitor emissions and introduce regulations and policies to protect workers and limit their exposure. You can learn more about policy-making processes in the next module. Here are some key messages that you've learned from this module. Thank you for attending.