How do common colds transmit?

@maria20 I think you can relax and not worry. The cold virus is spread by droplets, and the chance they traveled that far without falling to the ground is miniscule. Even if they traveled into his hose, your neighbor would then have had to touch the contaminated surface then his nose or eyes to get infected.
And you are right to open your windows to clear the air, but there is no way that can impact others from a distance.
I'm sorry you lost your neighbor, but I cannot see any way that you caused his death.

Thank you very much, your answer is really helpful since guilt is killing me.

I think the distance from the street to his house is abut 12 feet, so the chance of droplets to travel that far without falling to the ground and the air to spread them in different directions, is miniscule as you said.

It's just that I read too much and I am confused. And maybe my mind tends to think these thoughts.

Nonetheless, thank you

@sueinmn, I want to ask something else. So if the droplets entered his house through the open window then wouldn't be possible for him to inhale them?

I don't think you need to worry about this. Colds are caught through close contact like being sneezed or coughed on directly, or touching dirty tissues then touching nose or eyes. One or two random virus particles in the air won't infect a normal person, even an older man. As with most airborne viruses, infection comes from exposure to a quantity of virus particles over time. For example, sitting next to someone sick for an hour is FAR more risky than walking past someone on the sidewalk who coughs or sneezes as the pass by (and not right in your face.)
When you are outdoors, the enormous volume of air dilutes the particles and carries them away. Please set your mind at ease, walking outdoors with a cold, or opening your windows will not infect your neighbors.

Thank you very much for explaining this thoroughly to me. And also when I walked across his house I didn't even coughed or sneezed, I just talked for a sec so the particles I produced were lower in quantity. And if some of them traveled past 12 feet and went inside his house, they weren't much to infect him. So maybe this all was a coincidence.

You surely did not infect him by breathing outdoors 12 feet away from his house. Has anyone said he died from a respiratory infection? If so he was far more likely to have caught it from someone who was inside his home in any case.

No, as far as I know he died due to aging, he was bedridden for about 1 month or so. Although, I told my mom to ask his son because I want to be sure.

Also, I read in a paper that aerosol transmission of respiratory viruses requires an extended time in a poorly ventilated space to happen.

Exactly. That's why it is good to open windows and/or run a whole house fan to keep your home well ventilated. Also, indoor air is generally more polluted due household and laundry cleaners, exhaust from cooking, outgassing of synthetic substances, and the outdoor pollution that finds it's way in and stays.

Maria20,
I don't blame you for feeling guilty. Having your windows open and then your neighbor dying would make you wonder. However, Sue is right. Colds are caught through close contact and sneezing etc. My husband and I washed our hands a lot; especially after going to the dumpster. We also stayed away from crowded areas whenever possible. For instance, we went shopping early in the morning when there are less people. We kept our house clean. We also never got a flu shot. We didn't get a cold for over 15 years. My husband died of lung cancer last July but I still follow our guidelines and I haven't gotten a cold at all.
PML

@pml
Thank you very much for your answer, you are right it is just that my mind tends to wonder sometimes and make up scenarios.