DALY – Conditions for Spread

Daly = Disability Adjusted Life Years. Sairastavuus vakioitu elinvuosi is a number that describes a year lost from life expectancy due to harmful effects. 

For example, the following circumstances reduce life expectancy: If you lived like a Viking in the 950s - 4 DALY years are removed from life expectancy. If you lived in Delhi, the capital of India - 3 DALY years are lost from life expectancy.

The above assessments are calculated by averaging, such that if the annual average of fine particles in your breathing air is a certain number of micrograms per cubic meter (µg/m³), it affects life expectancy. If you breathe in 33.3 micrograms of particles in every cubic meter of air at a constant rate throughout your life, you will computationally lose one year of life.

For example, air pollution; if you move from an area where there are hardly any fine particles in the air to an area where the average is 100 micrograms of particles per cubic meter, you lose 3 DALY years from your lifespan.

This is a very logical equation: if you move from rural central Finland to downtown Delhi, you lose 3 years of your life simply due to the effects of air pollution. Similarly, individual events where the concentration of fine particles is temporarily high can be assessed. If the concentration of fine particles in the air is 2500 µ/m³ PM2.5 or higher, it reduces your lifespan in real-time due to harmful effects. 

How do fine particles then enter the indoor air?

First, let's rewind a bit and take a brief look back at the 1970s, when Finland also experienced the effects of the energy crisis. From then on, more energy-efficient homes began to be built in Finland, which has culminated in the 21st century with homes that are extremely effective at conserving heat. However, the downside is that they don't “breathe.”.

In other words, air does not move in or out of a house on its own. Of course, many other factors also affect air movement, such as the outdoor temperature compared to the indoor temperature. However, to summarize the ongoing news coverage, it can be said that there is a widespread problem with indoor air quality in Finnish homes. Fine particles from the outside air enter our homes through windows and doors, for example. 

A very simple equation; if you burn trash outdoors and your windows are open, some of the fine particles from the smoke will end up in your home's indoor air. We also produce fine particles ourselves through everyday activities. Even cooking itself causes fine particles.

During a Korean study (Kang 2019), researchers measured the effects of different food preparation methods on the generation of fine particles. What was surprising in the study was how much, for example, frying food creates both coarse and fine particles. Frying fish alone for over 15 minutes momentarily produces 4000-5000 micrograms of fine particles per cubic meter.

The equation must also take into account black carbon, as fireplaces are a common form of winter heating in Finland. But a fireplace isn't just for heating; it's part of Finnish living and a central element in creating a cozy home atmosphere.

Taking an extreme example of fireplace burning, an open fireplace can produce up to 25,000 micrograms of PM2.5 particles in spikes. If the fireplace were used for, say, 5 hours, the result of one fireplace burning would be a loss of about 50 minutes of life expectancy. However, Finnish homes usually have fireplaces with doors and good seals. Nevertheless, it's good to remember how much you want to keep the doors open and check the seals on the doors often enough. But fireplaces are not the only sources of black carbon in the home.

Candles themselves are a significant producer of black carbon. PM2.5 particles are generated as the candle burns, but the crucial situation where the amount of PM2.5 particles rises significantly is when it is extinguished by blowing. Several studies have shown that blowing out a single candle creates approximately 50-200 micrograms of fine particles per cubic meter, and these particles remain suspended in the air for an average of up to four hours.

If blowing out a candle is to be quantified, then assuming that the extinguishing produces 100 micrograms of PM2.5 particles that remain suspended in the air for 4 hours. This figure is divided by an instantaneous limit of 2,500 particles, whereby 100 micrograms are multiplied by 4 hours and then divided by the limit value of 2,500. This results in 0.16 hours, or 9.6 minutes. Therefore, blowing out one candle is almost equivalent to one cigarette in terms of indoor air pollution when viewed from the perspective of particle count.

In cigarette smoke, of course, there are thousands of other chemicals, over 70 of which are known to cause cancer, so let's not compare cigarettes and candles in the same category. Incense and scented sticks burned at home are also among these arch-enemies of good air quality.

The burning of incense sticks and cones is impure, allowing fragrant smoke to enter the home as effectively as possible. This is, therefore, the fundamental goal of incense. The amount of particulate matter that accumulates in the air during the burning of incense and cones can be as high as 4,000 micrograms per cubic meter. Thus, the negative impact of a single cone-shaped incense stick is up to 3.7 hours of life expectancy. 

The house smells clean, but can you see it in the indoor air?

Aerosols in cleaning products and household chemicals.
What does “aerosol” mean? An aerosol refers to particles suspended in the air. When people breathe, aerosols are released into the air, which can carry viruses, among other things. Fog is a good and visible example of a natural aerosol. Water droplets float in the air—aerosol—(aero + solution). An aerosol is therefore a mechanism created by the air that allows small particles to float and move through the environment.

Can a humidifier be harmful?

Finally, we'll take a look at another questionable device found in some Finnish homes: humidifiers, especially ultrasonic humidifiers.

However, the difference between, for example, blowing out a candle, which can momentarily produce 200 micrograms of particulate matter, and a humidifier, which is on for hours, is significant solely due to the humidifier's purpose and the continuous time it is used.

More and more research results are being found about humidifiers, and the unfortunate trend is that the results seem to be negative in terms of indoor air quality. 

Based on research, I am certain that there are many factors in indoor air that affect health. Health-adjusted life years are a useful way to illustrate the effects of indoor air quality. You can minimize the effects of indoor air quality by ensuring that your home’s ventilation system is working properly, thereby reducing your exposure to pollutants.