There have been two world wars in history, resulting in a total of about 70 million deaths. In this peaceful era, people enjoy the convenience of technology and the relaxation of travel, but they have not yet realized that in this era of advanced technology, people are vaguely experiencing the "third world war". The enemy this time is not human, but It's carbon monoxide - the silent killer.
December 5, 1952, was a day that made all Londoners panic. A heavy fog shrouded the entire city of London. Pedestrians walked by touching the walls. Cars drove slowly with their headlights on during the day. All flights were forced to be grounded. A heavy fog made the once lively London city so silent. In addition, 4,000 people died unexpectedly in the five days covered by the heavy fog, and more than 8,000 people died one after another in the next two months. This situation may have been a mystery at the time, but in today's, It is easy for society to explain the truth. That is, with a high concentration of carbon monoxide, 4,000 people died of hypoxia due to breathing difficulties in a short period of time. Although the remaining 8,000 people survived at that time, their body functions and brains were affected by carbon monoxide. In the following days their health got worse and worse, and eventually led to death.
The London smog event can be said to be the event with the highest number of accidental human deaths after World War II. Since then, more and more people have begun to pay attention to carbon monoxide gas, many companies have begun to put carbon monoxide detector products on the shelves, and many countries represented by the United Kingdom have also introduced laws on carbon monoxide, with the purpose of reducing the incidence of carbon monoxide poisoning as much as possible, thereby reducing mortality.
What is carbon monoxide?
Carbon monoxide is a colorless, odorless, tasteless, flammable gas which is produced by Incomplete combustion of carbonaceous materials. From chemical formula, it is made up of one carbon atom and one oxygen atom connected by a triple bond. Thats why people also call it as CO. In addition to this, it is also known as the silent killer because people often die of suffocation by inhaling carbon monoxide in their sleep.
Why carbon monoxide is dangerous?
Since carbon monoxide is diluted by the atmosphere in the environment and easily oxidized by oxygen to carbon dioxide, carbon monoxide has little impact on the environment. It is called a silent killer because when it is inhaled into the body, it will quickly combine with the hemoglobin in the human blood, so that the blood stops delivering oxygen to the brain, lungs, liver and other organs, causing people to unknowingly sleep in their dream, suffocated to death. This is the most dangerous cause of carbon monoxide.
Why carbon monoxide is dangerous?
Since carbon monoxide is diluted by the atmosphere in the environment and easily oxidized by oxygen to carbon dioxide, carbon monoxide has little impact on the environment. It is called a silent killer because when it is inhaled into the body, it will quickly combine with the hemoglobin in the human blood, so that the blood stops delivering oxygen to the brain, lungs, liver and other organs, causing people to unknowingly sleep in their dream, suffocated to death. This is the most dangerous cause of carbon monoxide.
Safe levels of carbon monoxide ppm
|
Concentration |
Symptoms |
|
0.1 ppm |
Natural level and clean air |
|
1 ppm |
Increased rates of |
|
3~7 ppm |
Increased rates of asthma |
|
5~6 ppm |
Baby weight is low if the pregnant woman is exposed to CO |
|
9 ppm |
Affects heart function in patients with coronary artery disease |
|
10 ppm |
Death from heart disease and congestive heart failure |
|
15~20 ppm |
Reduced motor capacity and alertness |
|
25 ppm |
Irreparable brain damage to the fetus |
|
27 ppm |
Cardiovascular disease increased by 21% |
|
30 ppm |
Earliest oneset of exercise angina attack |
|
35 ppm |
Oxygen masks are required |
|
50 ppm |
the maximum concentration that healthy adults can bear within 8 hours |
|
70~75 ppm |
Heart patients increased pain |
|
100 ppm |
Heart and brain damage |
|
200 ppm |
2 ~ 3 hours, slight headache and fatigue |
|
400 ppm |
Forehead pain within 1 ~ 2 hours; Life threatening after 3 hours |
|
800 ppm |
Dizziness, nausea and spasm within 45 minutes; Loss of consciousness within 2 hours; Died within 3 hours |
|
1600 ppm |
Headache, dizziness and nausea within 20 minutes; Died within 1 hour |
|
3200 ppm |
Headache, dizziness and nausea within 5 ~ 10 minutes; Died within 30 minutes |
|
6400 ppm |
Headache, dizziness and nausea within 1 ~ 2 minutes; Died within 10 ~ 15 minutes |
|
12800 ppm |
Died within 1 ~ 3 minutes |
It can be seen from the above table that 50ppm is the highest carbon monoxide concentration that the human body can tolerate, and people can last for 8 hours in a carbon monoxide environment with a concentration of 50ppm. Therefore, 50ppm is classified as a dangerous edge, which can also be called a warning line. The safe carbon monoxide concentration range is no more than 30ppm, which is also the concentration that will not trigger the alarm of carbon monoxide detectors.
|
Highest concentration people can tolerate in 8 hours |
50ppm |
|
Concentration which the detector will not be trigged |
30ppm |
Dangerous levels of carbon monoxide
As mentioned above, carbon monoxide at a concentration of 50 ppm is already the critical value of the dangerous value, which means that a concentration of more than 50 ppm is a dangerous concentration. When the carbon monoxide concentration exceeds 50ppm, people will experience dizziness, fatigue, drowsiness, and loss of consciousness, and the alarm will also goes off within 90 minutes. With higher and higher concentrations, people will experience the above symptoms earlier, and even cause people to die within several minutes. This is because high concentrations of carbon monoxide can quickly combine with hemoglobin, causing people to die from extreme hypoxia within 1 hour or even 3 minutes. The above conditions are for healthy adults, but if the elderly or children or sick people are exposed to carbon monoxide, symptoms may be more severe.
|
Concentration |
The detector goes off |
|
0~50 ppm |
N/A |
|
51~99 ppm |
Not activate before 60 minutes but must activate before 90 minutes |
|
100~299 ppm |
Not activate before 10 minutes but must activate before 40 minutes |
|
300ppm |
Activate within 3 minutes |
CO exposure limits in UK
The World Health Organization states that 9 ppm is the maximum indoor safe carbon monoxide level for 8 hours, as UK is a developed country with heavy industry, the limit for outdoor carbon monoxide concentration is 20~30ppm, and the limit for household and indoor carbon monoxide concentration is not more than 50ppm. This is because a person can be exposed to a carbon monoxide concentration of 50ppm for 8 hours. In addition to this, in 2018, the UK also updated the limits for carbon monoxide concentrations in the workplace: Carbon Monoxide Long Term (8 Hour) Exposure Limit (LTEL) is now 20ppm and the Short Term (15 Min) Exposure Limit (STEL) is now 100ppm.
|
CO limits in UK (8 hours) |
Concentration |
|
Maximum indoor safe level |
9 ppm |
|
Workplace level |
20 ppm |
|
Outdoor level |
30 ppm |
|
Household and indoor level |
50 ppm |
Indoor carbon monoxide concentration
If you turn on gas equipment such as heaters and boilers at home, and the indoor space is small, the indoor space is more airtight than the outdoors, so high concentrations of carbon monoxide will be generated in a short time. The following are the main sources of carbon monoxide indoors:
|
Equipment for home use |
Concentration of carbon monoxide |
|
Gas stoves |
5~15ppm |
|
Cigarettes |
20 ppm |
|
Kitchen |
800ppm |
|
Water heater |
1600ppm |
|
Water heater |
3200ppm |